Leaf Protein Extraction From Tropical Plants

Lehel TelekScience and Education,

Agricultural Research Service, Southern Region,U.S. Department of Agriculture,

Tropical Agriculture Research Station,Mayaguez, Puerto Rico

Protein and calorie malnutrition is widespreadin the less developed countries. Importing high-grade animal products, cereal grains, and animalfeeds puts a strain on these countries’ economies.Leaf protein concentrates (LPCs) should be serious-ly considered as additional protein sources. Leafprotein concentrates from alfalfa are prepared ona large commercial scale in Europe and the UnitedStates. Unfortunately, alfalfa has not been grownsuccessfully in the humid tropics, and a suitabletropical replacement is needed for leaf protein ex-traction.

At least 500 introductions of tropical plants havebeen tested at the U.S. Department of Agriculture’s(USDA’s) Tropical Agriculture Research Station inPuerto Rico. Potential plants for LPC productionhave been evaluated and selected for furtherresearch, Machinery has been developed whichmay be suitable for laboratory, on-farm, villagelevel, and commercial extraction. Further researchis needed in agronomy and leaf protein extractionand use. On-farm use is the most economicalsystem for the tropics, It is suggested that crude leafprotein concentrate be used as human food only inextreme emergencies.

Tropical Plants for Loaf

Protein ExtractionAt the present growth rate, world population will

double in the next 30 to 40 years. This populationincrease mainly will burden the lesser developedcountries in the humid lowland tropics, where thecurrent annual population growth rate is 2.3 per-cent and yearly increase in food production re-mains low. The demand for food of plant origin willcontinue to increase, and the supply of meat willdecrease because yields of cereal grains in thetropics generally are low and local production isconsumed by humans. This ever-widening foodshortage cannot be alleviated by conventional agri-culture alone. As an additional source of protein,leaf protein concentrates (LPCs) should be givenserious attention because leaves are abundant year-round in the tropics and many have high proteincontent. With suitable plant material, the yield per

hectare per year of leaf proteins can be at least fourtimes higher than that of seed proteins.

Leaf protein concentrates for animal feed cur-rently are manufactured from alfalfa in Europe, anda new processing plant was started recently in theUnited States. Because efforts to adapt alfalfa to thetropics have been only marginally successful in afew areas, possible tropical plant sources have beeninvestigated.

In 1978, a broad research program to find suitabletropical plants for leaf protein fractionation was or-ganized at the Tropical Agriculture Research Sta-tion, USDA (Science and Education) in Mayaguez,Puerto Rico. At least 500 introductions wereplanted and critically evaluated as potential sourcesfor LPC extraction (77) (table 1). The following cri-teria were used in selecting plants suitable for LPCproduction: high protein and dry matter (DM) con-tent, good protein extractability when freshly cut,and good regrowth potential. The plants should fixnitrogen, be erect and easily harvested mechanical-ly, and be nontoxic and low in antinutritionalfactors,

Freshly harvested plants were extracted in ablender with 600 ml ice water at high speed for 5to 10 minutes and filtered in a bag made of closelywoven fabric. The pressed green juice was heatedcarefully in a 2-liter Erlenmeyer flask immersed inboiling water and agitated with a slow motion stir-rer. At 550 C, a green coagulum formed and wasseparated by centrifugation, washed several times,and finally spread in thin layers on glass plates anddried, The supernatant from the centrifugation washeated careful ly to 64° and the white curdcoagulum that formed was separated by centrifuga-tion, washed with acetone, and dried in a rotaryevaporator. The liquid was further heated to 820.After cooling, a light tan precipitate formed andwas processed as the 640 fraction (see fig. 1),

The spontaneous coagulation of protein in thejuice extracted from some plants was observed dur-ing the survey of tropical plants. This phenomenonoccurred during extraction of leaves of cassava,Leucaena leucocephala; some Indigoferas,Desmodium, and Mimosa species; and many of thetree legumes of Mimosa, Cassia, and Pea subfami-lies. These plants have been classified as Type I(table 1). Another group of plants yielded a green

78

Leaf Protein Extraction From Tropical Plants ● 7 9

Table 1 .—Crude Protein Content of Tropical Plants

Amarantlius anclancaluius Hungary 1 2 . 3 2 6 . 6 I vA. caudatus Sweden 1 3 . 0 2 7 . 7 I vA. cruentus Taiwan 14.6 28.3 IVA. g a n g e t i c u s H u n g a r y 1 4 . 5 24.4 Ii’A. hypochondriacus Sweden 11.5 27.9 IvA. mantegazzianus Sweden 16.2 30.0 IV

COMPOSITAE

1111Helian thus uniflorus

H . annuusHungarySweden

2 9 . 92 5 . 4

CRUCIFERAE

HungaryP a k i s t a nGuatemalaYugoslaviaPolandHungaryFranceChina

22.514.21 0 . 810.41 2 . 61 1 . 81 1 . 61 4 . 4

1 3 . 81 2 . 21 4 . 210.21 0 . 81 4 . 11 4 . 01 2 . 61 2 . 31 8 . 2

3 9 . 81 9 . 12 1 . 03 0 . 030.82 1 . 12 6 . 4

2 4 . 4

2 7 . 12 2 . 32 4 . 82 6 . 42 4 . 02 0 . 61 9 . 41 9 . 41 7 . 62 2 . 6

I I I

I I II I II I I111111I I II I I

Brassica albaB . campestris

B. hirta

B. n a p u s

Brassica juncea IndiaCubaNepalInd i aTurkeyC r eec eUnited StatesUnited StatesPuerto RicoPuerto Rico

B. n i g r a

B. o l e r a c e aB. “ var . gongyloidesLepidium sativumN a s t u r t i u m o f f i c i n a l e

CUCURBITACEAE

I n d i aS . A f r i c aI n d i a

1 8 . 01 1 . 41 9 . 3

1 8 . 02 6 . 32 6 . 3

11I II I

Ben incasa h i s p i d aL a g e n a r i a s i c e r a r i aLuf fa cy l indr ica l

EUPHORBIACEAE

Cnidoscolus chayamansaManihot esculenta

MexicoColombia

1 8 . 82 0 . 8

2 6 . 32 5 . 5

11I

LECUMINOSAE

Aeschynomene falcataA. scabraA. i n d i c a

B r a z i lMexicoI n d i a

2 0 . 22 0 . 82 0 . 8

1 3 . 51 5 . 51 6 . 9

80 ● Plants: The Potentials for Extracting Protein, Medicines, and Other Useful Chemicals—Workshop Proceedings

Alysicarpus vaginal is

Cajanus cajan

Calopogonium muconoidesCanavalia ensiformis

C. gladiataCentrosema pubescens

Clitoria ternatea

Crotalaria alataC. argyrolobioloidesC. brachystachyaC. incanaC. juncea

Cyamopsis tetragonolobaDesmodium canumD. d i s tor tumD. in tor tum

D. perplexumD. sandwicenseGlycine wightiiIndigofera arrectaI . brevipesY-. c i r e i n e l l a

T-. coluteaI. confusaTA. cryptanthaI . echinataX. hirsuta

I . h o c h s t e t t e r iI. microcarpaI. mucronata

I . recrof lexaI. schimperiI. semitijugaI. spicataI. subulata

I . s u f f r u t i c o s a

I. sumatranaI . t e t l ens i sI. CeysmanniiI . t i nc to r i a

IndiaCeylonIndiaMexicoIndonesiaIndiaBraz i lPhilippinesIndiaPhilippinesIvory Coas tBraz i lCubaAustraliaIndiaKenyaBrazilArgentinaIndiaUSSRIndiaBrazilHawaiiSpainBrazilB r a z i l

A u s t r a l i a

S. A f r i c aChanaCosta RicaKoreaS. AfricaAustral iaIndonesiaS. AfricaTanzaniaNigeriaBrazilRhodesiaRhodesiaArgentinaPeruBrazilKenyaAfricaIndiaTanzaniaKenyaCubaBrazilMexicoAustraliaAfricaMalayaDem. Republic

20.118.62 4 . 02 .02 0 . 02 1 . 51 9 . 82 0 . 92 3 . 52 5 . 02 0 . 016.12 0 . 619.21 8 . 620.419.21 9 . 321.42 4 . 014.220.81 6 . 82 5 . 02 5 . 02 0 . 021.7

19.231.2

1 8 . 31 7 . 616.42 0 . 21 9 . 81 9 . 82 1 . 02 2 . 12 1 . 023.41 8 . 334.92 0 . 823.72 1 . 81 4 . 631.816.527.226.421.420.72 1 . 820.22 1 . 62 0 . 6

20.020.322.520.619.718.422.121.918.923.219.423.623.024.319.923.927.422.925.826.319.218.917.818.723.516.223.0

19.615.126.826.228.128.714.624.021.424.227.930.621.222.322.424.421.223.317.235.712.310.825.332.428.220.531.015.2

111I I I111111111111111111111111111111111IIII II I11II11III I II.111III111111

I I IIII III.I I I11111I I11I II II IIII I111111I I11I II I1111I II I I1111

Leaf Protein Extraction From Tropical Plants ● 8 1

Lablab purpureusLupinus albusL. angustifolius

L. l u t e u s

L. hispanicus

Macroptilium lathyroidesMacrocyloma uniflorum

Mucuna deeringianaP h a s e o l u s a c o n t i f o l i u s

P. c a l c a r a t u s

Psophocarpus tetragonolobusSesbania arabica

S : c a n n a b i n aS . e x a s p e r a t e ’

S. macrocarpa

S . sesban

Stizolobium aterrimum

S t y l o s a n t h e s g r a c i l i sS . humi l i s

Tephrosia aduneaT. cinereaT. incana ‘

T. noctif loraT. vogeliiVigna mungo

V. r a d i a t a

V. unguiculata

Zornia brasiliensisZ. diphyllaZ . l a t i f o l i a

MALVACEAE

Abelmoschus manihot

SOLANACEAE

Capsicum annuum

MalaysiaTurkeyHungaryS. AfricaHungarySpainPortugalSpainAustraliaPuerto RicoSouth AfricaMozambiqueIndiaAfghanistanIvory CoastHondurasPuerto RicoTurkeyAfghanistanIndiaBrazilArgentinaAustraliaMexicoIndiaChinaMexicoParaguayAustraliaBrazilVenezuelaUruguayKenyaIndonesiaBrazilPuerto RicoPakistanChinaIranTurkeyIndiaGuatemalaMexicoBrazilBrazilBrazil

Japan

Yugoslavia

21.518.820.422.622.220.420.620.218.818.621.017.218.822.219.720.120.621.822.219.820.420.622.019.820.619.420.6

21.222.021.822.224.223.824.423.620.419.321.019.318.921.118.819.020.219.820.0

14.6

20.0

27.719.518.816.616.119.219.819.219.526.421.332.618.315.820.823.722.029.930.021.420.920.619.219.927.629.427.422.320.918.918.014.019.321.413.212.323.624.016.922.922.219.519.415.816.815.8

14.0

2 2 . 4

I I I111111I I II I II I II I I111I I II I II I I11111111111111I I I111111111111I I II I I111111111111IVIVIv1111I II II II II I I111111111I I I111111I I I111111

111

111

82 ● Plants: The Potentials for Extracting Protein, Medicines, and Other Useful Chemicals—Workshop Proceedings—

Capsicum annuum Ecuador 1 2 . 5 19.9 I I IIsrael 20.0 21.8 111

C. chinense Ceorgia-USA 15.3 20.0 111Guatemala 15.3 23,.4 111Colombia 16.7 19.9 111

C. pendulum Mexico 18.0 19.8 111Chile 22.2 21.0 111California-USA 16.0 20.2 111

Solarium melongena India” 21.0 21.2 I I IChina 21.4 21.4 111

a Yield of different, fractions after extraction: I. Only one green fraction coagulated atroom temperature: 11.’0ne green fraction on heating to 55°C and one minute amount of light tanfracticln at 8 2 ” ; III. One green fraction at 55°. o n e white f ract ion at 64” and another lightcan fraction at 82°; IV. No distinct separable coagulum by heat f ract ionat ion.

SOURCE: Telek(77)

Figure 1.— Laboratory Method for Preparation of Protein Concentrate From Tropical Plants

FRESHLY HARVESTEDPLANT

Macerate

Press

PRESSED GREENCROP JUICE

I Heat 55° C

Precipi tate

Heatr

Centrifuge HeatLiquid

Centr i fugePrecipi tate Liquid

I I .DEPROTEINIZED

JUICECentr i fuge

82”’v

Solids Solid

Or Dry

GREEN PROTEIN WHITE PROTEIN12(ITEIH

SOURCE:Telek(77)

protein coagulum after the extracted green plant fractionation ofjuice was heated to 55°C and yielded a very small distinct protein

Solid

aqueous leaf extracts yielded threefractions: a greencoagulumat550

quantity of a light tan precipitateat820 C. This first C, a copious white protein precipitate at 64° C, andwas observed with leaf protein extract of sorghum- a smaller amount of a light tan precipitate at 820sudan grass hybrids and other grasses. Plants of this C. The most desirable plants for further studiesgroup have been classified as Type II. Type III is were selected from this group (table 2). A finalthe most important group of plants. Careful heat group, designated as Type IV, includes plants in

Leaf Protein Extraction From Tropical Plants . 83

Table 2.—Selected Plants for Leaf Protein Concentrates Production- — — -- .

% Protein % B i o l o g i c a lDry metter yield of dryMg/he/year protein nitrogen

Plants ma t t e r e x t r a c t a b i l i t y fixation Regrowth

B r a s s i c a n a p u sCentrosema pubescensC l i t o r i a t e r n a t e aDesmodium distortumLablab purpureusM a c r o p t i l i u m l a t h y r o i d e sPsophocarpus ce t ragonolobusSesbania sesbanVigna radia taV. unguiculata

28122811191220201625

SOURCE:Telek(77).

25.418.824.018.028.426.022.228.622.919.5

62.437.259.847.958.159.053.640.247.852.0

++

.+++++++

P o o r

GoodGoodGoodGoodGoodF a i rF a i rF a i rF a i r

which the proteins in the aqueous extracts do notprecipitate either spontaneously or after heat treat-merit. This was observed in extractions of Stylosan-thes gracilis, S. humilis, Nasturtium officinale, andAmaranths spp.

Pilot Plant Scale Preparation andNutritional Evacuation

Leaf protein concentrates from the tropical leg-umes Leucaena Zeucocephala, Vigna unguiculata,Clitoria ternatea, Desmodium distortum, Psopho-carpus tetragonolobus, Macroptilium lathyroides,Phaseolus calcaratus, Brassica napus, and Manihotesculenta were prepared on a pilot plant scale. Theplants were harvested in the vegetative stage ofgrowth, stored in a freezer, transported in a frozenstate, and processed in the pilot plant of the FoodTechnology Laboratory, University of Puerto Rico.Processing consisted of chopping to 2-cm piecesfollowed by soaking in 2-percent sodium metabi-sulfite, The soaked material was disintegrated ina hammer mill and pressed in a single-screw press.The expressed juice was heated with steam to 820C until a protein coagulum appeared. The hotcoagulum was collected in a basket centrifuge,pressed in a canvas bag under a hydraulic press,spread in a thin layer on glass plates, and driedin an air-conditioned, dehumidified room. Thepressed green juice of Leucaena leucocephala andcassava was left for 20 hours for self-precipitationof proteins at ambient temperatures (290 to 310 C).The settled precipitates were processed as outlinedabove.

The protein quality of the LPC was evaluated byusing rats (17). The tropical legumes Vigna ungui-culata, Desmodium distortum, Phaseolus

calcaratus, and Psophocarpus tetragonolobus gaveexcellent results, comparable to those obtainablefrom alfalfa LPC. These plants have low polyphenolcontents. Another legume low in phenols, Macrop-tilium lathyroides, gave relatively poor results [table3) due to its high saponin content. The differencesin rat growth probably are due to different aminoacid availabilities, as influenced by polyphenols andother compounds that may react with protein toform indigestible complexes.

The LPCs from the tropical legumes tested werefound to have amino acid contents similar to eachother and to reported values for alfalfa LPC and soy-bean meal (table 4).

Cassava and Leucaena were included in this nu-tritional evaluation, alongside the selected plantsources, to support our classification of plantsbased on the number of protein fractions. It wassuspected that the spontaneously precipitated pro-tein concentrate from Type I plants would have lessnutritional value. Rats fed LPC from cassava andLeucaena grew poorly. The data showed that pro-tein concentrates from these plants cannot be pro-duced by the accepted LPC processes.

About two decades ago, the use of tree leaves asa potential source of leaf protein concentrate wassuggested (60,64), and their possible use is still be-ing mentioned in literature, The presence of phe-nolic substances negatively affects the nutritionalvalue of the proteins prepared from tree leaves.After our studies of Leucaena leucocephala, we ex-tended our investigations to the other tree legumeslocated in Puerto Rico. The Leguminosae family ishuge (14,000 species) and extremely diverse, rang-ing from forest trees to shrubs to herbaceousannuals.

The results of our investigations, given in table5, clearly indicated that, with current methods,

84 ● Plants: The Potentials for Extracting Protein, Medicines, and Other Useful Chemicals—Workshop Proceedings

Table 3.—Protein Content of Tropical Plant LPC, Diet Composition, and Rat Growth Performance

D i e t Composition

CrudeProtein(:~cff z

Source of LPC L:C Corn

Corn-soy controlLeucaena 1 eucoce hala

k%%:m:%:!ed)~nihot esculenta 3t4. escul enta’~ escul enta 3

~ esculenta (acetone-washed)J!W!!! UnguiculataCl i toria ternataDesmodium distortumD. distortum (acetone-washed)~ophocarpus tetragonolobusMacroptil ium lathyroidesPhaseolus calcaratusBrassica napus CV. E a r l y G i a n t

----31.338.228.236.232.133.341.451.959.336.547.051.944.638.040.4

----31.926.135.527.631.230.024.219.316.927.421.319.322.426.324.8

6957

64.552.762.658.159.666.871.774.162.869.771.768.664.266.1

zsoy-beanHeal

Rat PerformanceAvg. Avg.

22:0 . 42.80 . 81.71.4---------0.8---------0.50.1

Avg. Dai iy DailyDa i 1

xGain Feed

Gain as Z of I ntake2

9) Control 9)7. z? .4f 100 16.411.50.92. 4: 12.5 11 .O~l .80.72.1 11.6~1.9l.of.gh 1?:; 9.7*1.41.8f.2gh 25.0 11.72 . 92.0?.59: 27.8 11 .121.21.22.39 16.7 11 .721.92.0:.4~h 27.8 14.811.75.8f.9f 8 0 . 6 18.221.86.72.4 93.1 17.7*1.65.4~1.of 75.0 73.021.16.6t.9f 91.7 16.6~2.O6.0fl.0f 83.3 17.2=1.33.02.57 41.7 14.9~2.O&()?.6f 83.3 13.5~1.26.12.9 84.7 17.4tl.5

ProteinE f f i -

ciencyRatfo

‘N X 6.25~~an ~ standard deviation.

Means followed by differentletters differ at p 0.01.~Dried in microwave oven.● Dried in air-conditioned room.

SOURCE: Cheeke(17).

good quality leaf protein concentrates for nonrumi-nants could not be prepared from many of the legu-minous tree leaves, especially those of Type Iplants. However, some of the leaves of the Legu-minosae definitely could be used as feed for rumi-nants after careful analysis for toxic ingredients.

Stylosanthes humilis and S. guianensis offeredpromise for leaf protein extraction. These valuablepasture plants are perennial legumes with high DMyield and a protein content that is as high as thatof alfalfa. However, during maceration of theseplants, a thick emulsion formed which could notbe separated from the fibrous material either bycentrifuging or by pressing. On heating, the emul-sion thickened and separation became even moredifficult. After unsuccessful processing experi-merits with 10 different cultivars, further researchwas abandoned.

The lush vegetation of the humid tropics is oftenconsidered to have a high potential for animal pro-duction. The grasses are an extremely large familyof more than 10,000 species, Tropical grasses havea capacity for photosynthetic high rates, grow yearround, and show excellent regrowth after repetitivecutting. However, the natural nitrogen (N) contentof grasses is relatively low and heavy nitrogen fer-tilization is required for high DM production.

Our experiments with forage sorghum (MilloBlanco) and sudan hybrids showed encouragingyields (71), However, the extractions were disap-pointingly low: 28.6 percent extractable proteincompared with 52.4 percent for legumes. Investiga-tions of tropical grasses as sources for leaf proteinextraction were suspended. It was concluded thatthe ever-increasing cost of nitrogen fertilizer, thehigher processing costs due to lower crude proteincontent, low extractability of tough fibrous plantmaterial, higher energy requirement of the disinte-grator, and the lower quality of protein would makethe process uneconomical. With a low initial N con-tent, the extraction of protein from grasses couldreach the point where the pressed residue, the mostimportant byproduct, could not be used by rumi-nants.

Our relatively short systematic investigation ofpossible tropical plant sources for leaf protein ex-traction and fractionation produced the followingvaluable results:

1, Plants equivalent to alfalfa in yield, extract-ability, and nutritional quality were selected,

2. It was recognized that in the Tropics a singlecrop cannot be used for year-round produc-tion; a pattern of different plantings has to beformulated for rainy and dry seasons. Hello

Leaf Protein Extraction From Tropical Plants ● 8 5——. —

Leucaena

Table 4.—Essential Amino Acid Composition of LPC From Tropical Species

gm amino acid/100 g recovered amino acidsSource of L P C A r g H i s t I so I Leu Lys Meth Phe Thr Val 1/2 cyst

l e u c o c e p h a l a 6.4

Manihot esculenta a

Manihot esculenta b— —Vigna unguiculata

Clitoria ternatea

Desmodium distortum—

Psophocarputs tetragonologus

Macroptilium lathyroides

Phaseolus calcaratus

Brassica napus

Medicago astivac

6.3

6.0

6.7

6.1

6.1

6.2

6.6

6.0

6.2

6.5

2 . 2

2.4

2,4

2,4

2,2

2.6

2.6

2.5

2.5

2.6

2.3

a Dried in air conditioned r o o m .b Dried in microwave oven.c Iiuzmich>’ and KollJer (1!177) .

SOURCE: Cheeke (17),

5.0

5,4

5.2

5.4

5.8

5*5

5.4

5.6

5.4

5.3

5.6

3.

4.

and Koch’s (32) statement that “When it ispossible to use the raw material of one or onlya few plant cultures—e. g., in tropical regions,the technological problems are not as great”now seems inaccurate.Our studies seriously question the popular be-lief that cassava, Leucaena leucocephala,other tropical tree leaves, and tropical grassesare potential sources of LPC.The protein pattern, or number of proteinfractions obtained by heat fractionation, wasdiscovered to be a rapid preliminary methodto screen plants for protein extraction poten-tial. Type I plants have a low probability ofyielding good LPC.

Machinery of Leaf ProteinFractionation

The development of economical equipment forsuccessful farm-size leaf protein processing is a ma-jor task. Hjalmar Bruhn (14), a leading authority inthe United States on farm machinery designed es-pecially for protein extraction wrote: “I don’t see

9.1

4,3

9.1

9,4

9.1

9.4

9.3

9.7

9.2

9“. 3

9.3

6.3

6.5

6,4

5,8

6.1

6.5

6.4

5.4

6,4

5.8

5.9

2.4

2.5

2.4

2.7

2.4

2.6

2.5

2.7

3.0

2.6

2.3

5.9

7.0

6,8

7*5

7.2

7.3

7.1

7.5

7.1

7.5

5.9

4.8

4,9

5.2

5.3

5.2

5.0

5.2

5.0

5.1

5.3

5.1

6.0 0,7

6.0 0.8

5.7 0.7

6,4 0.6

6.2 2.0

6.0 0.6

6.4 0.6

6.4 0.6

6.2 0.7

6.4 0.7

6.3 0.6

much hope for any appreciable protein productionunless there are well engineered machines that arecommercially available at farm machinery prices. ”

The separation of plant juice from the fiber is atwo-step process: The rupture of the plant cells bymaceration and the separation of the juice andfiber. Cell rupture is the most energy intensive proc-ess in leaf protein extraction.

Macerating

Initially, macerating sugarcane rollers were used,but such equipment proved to be ineffective, Theoverall capacity was low when operating underhigher pressure, the power requirement was high,and the machine was very heavy for portable farmuse.

Varying degrees of cell disintegration can be ac-complished by hammer mills of different construc-tion. These should be used when a high percentageof protein is to be extracted, when the initial plantmaterial has a high protein content, or when thepressed crop will not be used as forage for cattle.

The evolution of small equipment designed inRothamsted Experimental Station in England

86 ● Plants: The Potentials for Extracting Protein, Medicines, and Other Useful Chemicals—Workshop Proceedings

Table 5.—Protein Content of Leaves of Tropical Legume Trees

% P l a n tP r o t e i n t y p e

1 .Cass ia S u b f a m i l y ( C a e s a l p i n i o i

B a u h i n i a a l b a . . . . . . . . . . . . . .Bauhinia candida . . . . . . . . . . . .Bauhinia galpini. . . . . . . . . . . .Bauhinia purpurea. . . . . . . . . . .Bauhinia reticulata. . . . . . . . .B a u h i n i a v i o l a c e a . . . . . . . . . . .

Cassia moschata. . . . . . . . . . . . .Cassia nodosa. . . . . . . . . . . . . . .Cassia spectabilis. . . . . . . . . .

Delonix regia . . . . . . . . . . . . . . .

Libidibia punctata. . . . . . . . . .

T a m a r i n d s i n d i c a . i . . . . . . . . .

2. Mimosa Subfamily (blimosoideae)

Albizia adinocephala... . . . . .

deae)

17.4313.2016.228 . 9 2

12.5911.80

6.478.58

14.2422.8525.90

10.57

14.89

10.03

20.80

14.7716.60

Enterolobium cyclocarpum. . . . 26.58

Inga laurina . . . . . . . . . .Inga Vera. . . . . . . . . . . . .

Leucaena leucocephala.

Parkia biglandulosa. . .

P i t h e c e l l o b i u m d u l c e . .

Samanea sampan . . . . . . ..

. . . . . . 18.34

. . . . . . 21.44

. . . . . . . 26.80

. . . . . . 12.85

. . . . . . 18.43

● . . . . . 17.41

3. Pea Subfamily (Faboideae)

Dalbergia sissoo. . . . . . . . . . 1 2 . 9 1

E r y t h r i n a poeppigiana.. . . . 1 9 . 1 3E r y t h r i n a v a r i e g a t a

orientalis. . . . . . . . . . . . . 1 7 . 9 4

Myrospermum frutescent. . . . 1 9 . 4 2

I

III

111

I

111I

111

I

I

I

I I I

II

I

II

I

I

111

111

111

I I I

111

111

SOURCE: Telek, unpublished.

Leaf Protein Extraction From Tropical Plants ● 8 7— —

before 1960 has been published by Davys and Pirie(19). Later, to standardize processing methods, newequiment was built and evaluated in several coun-tries. The new pulper contains 58 fixed beaters with2 mm clearance from the drum. The rotor is drivenby a s-horsepower (HP) motor. Field experimenta-tion has shown that units can be mounted on aLandrover whose engine drives the pulper. Thestandard model takes 1 kg crop/rein, but could beincreased to 6 kg/rein. The capacity to macerate 360kg/hr makes this pulper useful at the village pro-duction level (61).

The large-scale fractionation machinery at theNational Institute of Research on Dairying (NIRD),Shinefield, England, was developed from a designof Davys and Pirie (20). The pulper has 32 arms thatrotate in a cylinder and are driven at 1,100 rpm bya 32.3 HP motor. The total power requirement is6 to 8 kilowatt hours per metric ton (kWh/MT) ofinitial crop. More powerful disintegrators of thistype were built for the large industrial process.These machines will not be discussed in detail,since they are not related yet to tropical production.

The most energy efficient way to macerate at highcapacities is by using extrusion, where the plantmaterial is forced through an orifice (50). High ca-pacity rotary extrusion macerators have been de-signed by Basken (5) and Nelson, et al. (56). Thesemacerators consist of an internal roller operatingagainst a die ring perforated by radial orifice holes.One of these experimental macerators operatedwith 22.1 MT/hr capacity at a power input of about1.7 kWh/MT (fig. 2).

Pressing

The performances of the double screw, singlescrew, and belt presses used in leaf protein prepara-tion in British research and a commercial crop dry-ing plant were evaluated by Shepperson, et al. (68).Screw presses are effective machines for removingjuice from the macerated forage, but their energyconsumption is higher than that of some other pressdesigns due to rubbing and shearing action in thepress. industrial screw presses are expensive andless suitable for mobile installation (fig. 3). Platenpresses have been used in small or medium installa-tions and can have a capacity of 1.8 to 3.6 MT/hr.The power consumption is low. Belt presses werefound to have limitations in the forage dewateringprocess because maximum pressure is limited bythe nature of belt tensions. If new synthetic beltscould be produced, this system could be built as rel-atively light equipment. Several presses for LPCproduction were described by Pirie (61) (fig. 4). A

Figure 2.— Rotary Extrusion Macerator

Photo credit: Courtesy of H. D. Bruhn and R. J. Koegel

Figure 3.— MINIPRESS Ml IB.

Photo credit: Courtesy of N W Price

commercially available cone press was evaluatedby Koegel, et. as. (51) and gave satisfactory resultsfor final moisture content and energy requirement.A new press was designed with a capacity to press16.5 MT/hr of freshly macerated material to a finalmoisture content of 65 per cent or less. The weightof the press is 3.1 kg. The results of the evaluationof the cone press for forage fractionation were re-ported by Straub and Koegel (73), who suggestedsome changes in cone rotation speed. The averagetotal energy required for the press was low; 0.95KWh/MT. The sum of energy requirements formacerating alfalfa and pressing it in the cone pressis about 3.25 kWh/MT (Nelson et al, 1981). Energy

88 . Plants: The Potentials for Extracting Protein, Medicines, and Other Usefu/ Chemicals—Workshop Proceedings

Figure 4. —Cone Press

Photo credit: Courtesy of H. D. Bruhn and R. J. Koegel

requirements for maceration and pressing of fresh-ly harvested forage are compared in table 6.

Professor Bruhn (14) converted meat grindersinto good, medium, and miniature size systems forlaboratory evaluations to replace Waring blenders(fig. 5). The high-speed electric blenders do notduplicate industrial crushers; they chop the fibersinto small particles, which will be mixed into thegreen leaf protein concentrate during the heat-coagulation process.

Separation of Protein Concentrate

Juice, if not directly fed to animals, should beprocessed without extensive delay. Separation ofprotein is accomplished by several methods (table7); however, the most convenient is coagulation bysteam injection. An automatic system was devel-oped by Straub, et al. (75), to coagulate the juice andseparate the coagulated protein from the brownjuice. The incoming juice was preheated by a heat

Table 6.—Energy Requirements for Producing Leaf Protein Green Juice

Process h p / h / t o n R e f e r e n c e

F i e l d h a r v e s t i n g

Di rec t cu t and c h o p

M a c e r a t i o n

E x t r u s i o n

R o l l c r u s h i n g

Hammer mill ing

Hammer mill ing

Press ing

S c r e w p r e s s

R o l l p r e s s

H i g h - c y c l e p l a t e n

ConeSOURCE: Compiled by Telek, 1983

3 - 7*5 1 - 2.5 ASAE Yearbook, 1975

7.5 - 30 2.5 - 10 Basken et al., 1975

15 - 90 5 - 30 f?

42 - 150 15 - 50 11

16.5 5.5 Carroad et al., 1980

6- 3 0

15 -30

15 - 30

---

2 “- 10 Basken et al., 1 9 7 5

5 -10 t?

0.5 - 1 ?t

1.14 Bruhn and Koegel , 1982

Leaf Protein Extraction From Tropical Plants ● 8 9—

Figure 5.— Rebuilt Meat Grinder as Miniature ScrewPress

Photo credit: Courtesy of H. D. Bruhn

J U I C E

Table 7.—Separation Methods of

Treatment

HEATING not measured

80°-840 C

60°and 84°

55° , 64° , 82°

exchanger, salvaging the heat from the brown juice.The generally accepted energy requirement is 50kg of steam/MT green crop.

Low-cost and simple technology systems for leafprotein separation and recovery using on-farm leveloperations have been reviewed by Straub, et al. (74).A farm-scale centrifuge designed to separate sus-pended solids from animal waste was evaluated. Ithad a slower than expected acceleration rate andthe through-put rate was low: 5 kg/rein. Other sys-tems were designed based on flotation, consistingof a stainless steel tank (0.25 m x 0.36 m x 2.64 m)with a working capacity of 211 liters and a built-insteam injector. The flow rate was 42 l/rein with ahold time of approximately 5 minutes for floccula-tion in the tank. The mechanical skimmer was ro-tated at a speed of 2.3 m/min, and the paddles wereimmersed in the tank to 5 cm below the spillway(fig. 6).

The belt filtration system consisted of an 8.5-mlong continuous woven polyester belt with a vari-

A C I D

ORGAN I CSOLVENTS

ethanolacetone

n butanol

ANAEROBICFERMENTATION

LPC From Green Juice

Fractions

g r e e n a n d w h i t e

g r e e n

g r e e n a n d w h i t e

g r e e n a n d t w o w h i t e s

g r e e n

g r e e n

g r e e n

green

green

Reference

Rouelle, 1773

Pir ie , 1971

Edwards et al. , 197!— .

Telek, 1979

Pirie, 1971

Huang, 1971

All i son, 1 9 7 3i n H o v e a n d B a i l e y ,1 9 7 5

S t a h m a n , 1 9 7 8

A n e l l i e t a l . , 1 9 7 7— .K n u c k l e s , 1 9 8 0

SOURCE: Compiled by Telek, 1983

24-503 0 - 83 - 7

90 • Plants: The Potentials for Extracting Protein, Medicines, and Other Useful Chemicals—Workshop Proceedings — — - . . — . . — — — — — — —

Figure 6.— Flotation Separator

H E A T E X C H A N G E R1

1

PLANTJUICESUPPLY

I sv2 T V2

I STEAM.SUPPLY

Sv1 T V1 T V3 Q C V

I I I I I ISK IMMER

I I I I I

S T I L L I N G T R O U G H ,

\

S 3

Plant Juice Protein Processing System ControlsSymbols: CV - Check Valve s - Sump

- Solenoid Valve T - Temperature SensorTV - Throttling Valve VR - Vacuum Release Valvep - Pump QCV- Quick Closing Valve

SOURCE: Straub, et al, (75).

able moving speed of 3.0 to 15.2 m/min. (fig. 7). Thebelt filter was fitted with a 0.25-m long x O, S-m x0.3-m tank to allow for flocculation of the juice pro-tein. This provided an average 1- minute hold timefor the heat treated juice prior to being spilled ontothe traveling belt by a paddle wheel assembly whichrotated at a rate of 20 rpm. There was an initial freedrainage section on the belt. This was followed bya vaccuum box dewatering section. The materialthen was scraped off to pans by a spring-loadeddoctor blade (fig. 8). The evaluation of this processshowed that flotation provides good recovery. How-ever, the protein concentrate was dilute; it was lessthan 12 percent solids. The filtration provided mod-erate levels of solids, but had poor recovery rates.Use of flotation as pretreatment to belt filtrationprovided improved recovery and moderate solidconcentration. Mean solid levels of proteins sepa-rated by various methods are shown in table 8. Theresults using this relatively complex machinery aresomewhat disappointing, and further refinement is

needed. In an on-farm operation, such as hog rais-ing where a wet product can be used, this solid levelwould be acceptable. The protein concentrate couldbe mixed with barley or cassava chips for immedi-ate use or partly extruded and sun-dried for shortduration storage.

LPC Extraction at Village Level

The most basic application of leaf protein frac-tionation is at the village level. The operation is sim-ple. Production should be geared to consumptionby farm animals to avoid preservation and storageproblems, The system, using the pulper and pressdeveloped at Rothamsted Experiment Station,England, and purchased by donors, has beenstudied in Pakistan (66), India, and Sri Lanka.

In a rural resettlement of people from urbanslums in Pakistan, a trial has been suggested to test-market LPC produced by this machinery for dairy

Leaf Protein Extraction From Tropical Plants . 91—

●

●

n

w

I 1 I al

n

I I 1

n n

I I I

c

COACULATIONTANK

SOURCE: Straub, et al. (74)

Figure 8.— Belt Filtration

Photo credit Courtesy of F/. D. Bruhn and R. J. Koegel

cattle and green LPC for local sale. The labor forcewould be recruited from the resettled familiesunder the supervision of trained personnel.

Indian and Pakistani scientists are cooperatingin the leaf protein work. Dr. Shah of the PakistanCouncil of Scientific and Industrial Research vis-ited Mysore, Coimbatore, and Aurangabad to learnof the Indian progress in implementing village-levelLPC production.

The work in Aurangabad, India, is the most rele-vant to practical application of any in progress. It

DOCTOR BLADE P R O T E I N

Q )

attempts to establish a commercially viable LPCproduction unit at a village farm, using a simplifiedscrew press that Pirie (62) has been developing fora number of years (fig. 9).

This press accomplishes both cell rupture andjuice expression in a single press. A similar unitwas built in the workshop of Marathwada Univer-sity. The press is driven by a 3-HP motor. The juiceis drained over a vibrating screen, then precipitatedin a thermostatically controlled oil bath. The coag-ulum is filtered through cloth stockings (fig. 10).The locally constructed equipment could be scaledup according to need (18).

Joshi, et al, (42), reviewed the prospects and prob-lems of leaf protein production on a small farm inBidkin, an Indian village about 25 km from Aur-angabad. The green protein concentrate made fromalfalfa was used as a milk replacer for calves, a spoultry feed, and as human food. The pressed cropwas remixed with solubles and fed immediately tocows. They accepted the material willingly, how-ever, they rejected it when offered it the next morn-ing. Equipment and a dairy unit of 5 to 6 cowswould cost at least $4,450 (Rs 35,500*), an excessiveexpenditure for a small farmer. Joshi suggested that,in the immediate future, both of the products ofgreen crop fractionation be sold in the market. Thisproject was supported by the Meals for MillionsFoundation, and its economics were evaluated byBray (13).

A flow chart for the process is shown in figure11. After the crop is pulped, it is pressed to yieldgreen juice and fiber. Heating the juice yielded 25

“’1’he exchange rate of the Indian rupee (Rs) is calculated atKS 7.8 I)er $U. S.

Leaf Protein Extraction From Tropical Plants ● 9 3

Figure 9.-Simplified Screw Press

Photo credit: Courtesy of N W. Pirie

Figure 10.-Screw Press Designed and Built in Aurangabad, India

HOPPER FRESH CROP SCREENMOTOR REDUCTION UNIT

SOURCE Courtesy of R. N. JoshiCOAGULUM

94 ● Plants: The Potentials for Extracting Protein, Medicines, and Other Useful Chemicals— Workshop Proceedings—

Figure 11.— Process Flow Chart of Leaf Protein Fractionation on Village Level in India

Cut and Pulp

Green, Juice

Pur i fy

IIII

I

S e p a r a t e - P r o t e i n ~

SOURCE: Bray (13)

kg LPC from about 1 MT of freshly cut alfalfa. In Equipment Costsa-variation of this process, the pulped crop is ex-tracted with the solubles from the protein precipita- The cost for both processes was calculated at

tion phase, to yield an enriched fiber fraction for about $3,200 (table 9).

feeding ruminant animals. The leaf protein concen-trate—containing 60 to 65 percent protein, 22 to 24 Landpercent lipids, and carotenoids (pro-vitamin A)–could be consumed by people or nonruminant ani- Since the extraction process requires about 1 MTreals, or used as a milk replacer for calves. The in- of fresh alfalfa per day, the produce from about 2put requirements for this process are indicated ha would be needed to keep it operating continu-below. ously.

Leaf Protein Extract/on From Tropical Plants ● 9 5—

Wash Tank

C u t t e r

P u l p e r

D e w a t e r i n g p r e s s

J u i c e p u m p

L i q u i d C y c l o n e

W a s t e R e c e i v e r

H o l d i n g T a n k

H e a t e r / C o a g u l a t o r

C u r d F i l t e r

Beam Pres s

H o l d i n g T a n k

Mix ing /Wash Tanks

Beam Pres s

Table 9.— Equipment Costs for LPC Preparationon Village Level in India

Rs 1500

1540

5500

4500

1 1 6 0

80

160

1700

100

320

160

T o t a l C o s t Rs 18870 ($2,359. )

I n s t a l l a t i o n 2 5 % 4720

1890

Rs 25480 ($3 ,185. )SOURCE: Bray (13).

Crop Cost and Income Electric Power

Current costs for alfalfa vary widely. With an ex- The power required is 5.6 kW for pulping andpected yield of about 100 MT of fresh alfalfa/ha/yr, 6.75 kW for pressing at $0.034 per kWh.a farmer would receive $1,600, an income higherthan he would get raising other crops. Fuel

Labor Requirements and Salaries The fuel is low quality coal that would cost about$0.002/kg LPC. The production cost per kg LPC is

For an 8-hr day, the salary of the supervisor is summarized in table 10.$1.50, $0.99 for operators, and $0.75 for helpers. Suggested retail price for 1 kg LPC would range

96 • Plants: The Potentials for Extracting Protein, Medicines, and Other Useful Chemicals—Workshop Proceedings.- — — —

Table 10.—Leaf Protein Production Cost Summaryat Village Level in India

Process 1Pressing)

Raw material (net cost) Rs 1.02/kg L P CLabor and supervision 1.72Power 0.58Fuel 0.13Maintenance 0.66Supplies, etc.

DepreciationInterest expenseOther fixed charges

Total fixed costs

0.29Rs 4.40 = 55¢

0 09 10 . 6 00.25

Rs 1.76 = 22¢

Total production cost Rs 6.16/kg LPC = 77¢

SOURCE Bray(13)

from $l,19 (Process 2) to $0.79 (Process l) Leaf pro-tein probably would be incorporated into a finalfood product, then sold. For example, in the Coim-batore feeding program, LPC was mixed with cas-sava flour and sugar and fed to children as a softsweet mixture called a laddu. If a similar productcontaining leaf nutrient concentrate were to be soldin the market, it could be priced at $0.50 per kg.For only $0.025 to $0,03 per day, a child could ob-tain 50 percent of his daily protein, iron, and cal-cium and 100 percent of his vitamin A from sucha product.

Conclusions

The following conclusions are drawn from thisstudy (13):

1. A green crop fractionation/leaf protein unitcould be easily operated in a village.

2. The cost of the equipment is low enough tobe affordable by village cooperatives.

3. On a nutritional basis, leaf protein would bemuch less expensive than most of the proteinfrom grain legumes consumed in the area.

4. An LPC-containing product that would pro-vide 50 percent of the daily protein require-ment of a child would be affordable by the ma-jority of the Indian poor.

In Coimbatore, Friesian, and Jersey cows are con-suming the pressed crop, and in preschool nurser-ies children are getting the LPC in laddu, a fooditem developed by Dr. Devadas, which consists ofa mixture of leaf protein with jaggery (a crude sugarmade from the sap of a palm tree), cassava flour,pearl millet flour, and sesame seed molded into soft

balls. It was fed to the children as a snack. The ob-ject of her research was to evaluate the nutritivevalue of LPC through feeding programs for 600 pre-school children for a period of 3 years.

On-Farm Use of LPC

The basic principle of leaf protein fractionationis that some plants, mostly the Leguminosae, con-tain much higher levels of protein than are neces-sary for ruminant nutrition. This protein can be re-moved without negatively affecting the growth ofanimals. On the other hand, nonruminants are un-able to digest high contents of cellulose and can-not consume the amount of dry matter required tosatisfy their protein requirements. Using proteinfractionation, plant material can be separated intoone product suitable for nonruminants and anothersuitable for ruminants. Experimental proof indi-cates that the process can double meat productionin a given area (35).

The concept of on-farm use of leaf protein frac-tionation is that a weather-independent system canbe devised in which the processing takes place ona farm and at least one of the products is used atthe production site. The ideal situation would bea combined dairy and hog production farm usingall of the products grown onsite, thus reducingtransportation expenses, storage costs, and spoil-age. This approach has been researched in Britain,Australia, and the United States.

The research team of the University of Wiscon-sin, under the leadership of Professor Bruhn, con-tributed the most in developing new concepts inmachinery designs for this system (14). Researchat the University of Wisconsin at Madison has con-centrated on development of a weather-independ-ent, on-farm forage harvesting system using a pro-tein fractionation process. After harvesting, themain product is pressed forage, which can be pre-served directly as silage. The prime objective is aquick reduction in the moisture content of the freshforage from approximately 80 to 65 percent, a de-sirable moisture concentration for proper fermen-tation in a silo (31). By this process, field losses canbe minimized to about 2 percent, a reduction from32 percent or higher when the crop is preservedas baled hay. The pressed residue contains 50 to80 percent of the dry matter of the original greencrop. It retains 70 to 80 percent of its original pro-tein content, which is substantially higher than thatof sun-dried hays.

Leaf Protein Extraction From Tropical Plants • 97

Use of Pressed Residue

Use of the pressed residue is the key factor in leafprotein fractionation. The maceration will make thefibers more digestible by ruminants. In sheep feed-ing trials, the pressed crop from either alfalfa orryegrass was equally effective when fed freshlypressed or as silage (80,81). In steers fed a peren-nial ryegrass and Italian ryegrass mixture, the meanintake of whole and pressed crops was equal, andthere was no significant difference in weight gain(40). The liveweight gains in cattle fed the pressedcrop of perennial ryegrass were found to be signif-icantly higher than those of cattle grazed on wholeryegrass ad libitum (35). Other research concludedthat pressed residual can be fed directly to rumi-nants with as good results as the original nonfrac-tionated plant (59).

Use of the Juice

The DM content of the green juice is low (8 to10 percent). The isolation of green protein is an ex-pensive process. The most economical use wouldbe to feed it directly to hogs to minimize storageand preservation expenses. The green juice con-tains proteins, carbohydrates, and lipids. Enzymespresent in juice degrade proteins rapidly, especiallyduring warm days (69), and the soluble carbohy-drate fraction ferments in 24 hours (4). Therefore,the process must be geared to the feeding time ofthe animals. Houseman and Connell (34) effective-ly replaced separated LPC and conventional seedproteins and dried LPCs by direct feeding of grassjuice.

According to Braude, et al. (11), grass and alfalfajuice can replace half of the protein supplement(soybean or fish meal) in the feed of growing pigs.However, feeding experiments carried out in Wis-consin gave disappointing results. Pigs did not con-sume alfalfa juice even when their drinking waterwas withheld.

The most economical method for isolating pro-teins from green juice would be by anaerobic fer-mentation (1,49,72). Bacteria normally present onleaves fermented juice samples of many differentplants (alfalfa; corn; oats; pangola, elephant, brome,and sudan grasses) in sealed containers. The initialpH of 5.5 to 6.0 dropped to 4.5 after 48-hour fermen-tation. Amino acid analyses of the fermented andspray-dried juice protein showed that it contained40 percent more cystine and 12 percent more meth-ionine, The protein yield was 11 percent lower thanthat prepared by heat precipitation. However, pigs’acceptance of feed containing the fermented prod-

uct, especially in high proportions, was always low.An important need exists for animal nutritioniststo convert the fermented LPC product into a pala-table swine feed.

In contrast to the village use concept stressed forLPC research, a serious investigation of process de-velopment for commercial LPC production was ini-tiated in 1967 at the Western Regional ResearchCenter of USDA in Berkeley, California. A largenumber of papers have been published on everyphase, including use of the different products. Ahighly mechanized process evolved which is cov-ered by several patents (8,10), Several reviewsdescribe the development of the Pro-Xan process,the commercial production method for obtainingleaf protein concentrate from alfalfa (22,23,52).Figure 12 describes the flow sheet of the process.

The original process has undergone severalchanges. Energy saving and pollution reductionwere the main targets of process research; im-proved machinery was selected to accomplish thesegoals. The economies of producing Pro-Xan werestudied by the USDA Economic Research Serviceand updated after major process changes (28,82).

The first commercial application of the Pro-Xanprocess was by France Lucerne, the largest pro-ducer of alfalfa dehydrators in Europe. The firstpilot plant was constructed next to a dehydratorand produced 2 MT/day of green protein concen-trate. In this process the pressed residue is addedto the pelleted, dehydrated alfalfa. Also, the con-centrated solubles are recycled to the pelletingoperation. The success of the operation lies in thecentral location of the plant in Champagne, thelargest alfalfa growing region in France; its well-organized sales operations; and the barge canal,rail, and highway connections available for ship-ping its products economically. A larger plant wascompleted in 1981 and 7,000 MT of green proteinconcentrate Pro-Xan are being produced yearly.France annually produces 900,000 MT of dehy-drated alfalfa. Sixty percent of this is produced andmarketed by France Lucerne in Champagne.

Alfa-Laval and France Lucerne agreed to sell two600 MT/day production plants to the Soviet Union.The process is based on Pro-Xan technology mod-ified by France Lucerne using alfalfa as plantmaterial (3).

In conventional dehydration, alfalfa containing20 to 22 percent dry matter is chopped, transportedimmediately to the plant, and dehydrated to 90 to

98 ● Plants: The Potentials for Extracting Protein, Medicines, and Other Useful Chemicals—Workshop Proceedings—

C H O P P E D

ALFALFA

Figure 12.—The Pro-Xan Process used by the Valley Dehydrating Co.

I . — J

I - S T E A M

SOLUTION .

SOURCE: Edwards, et al (25)

92 percent dry matter in the rotary drier. This proc-ess generally produces a product higher in proteincontent than hay or silage produced from the samefield, without the losses occurring during hay mak-ing and ensiling. Dehydration is less weather de-pendent than the other forage conservation tech-niques and is highly mechanized. The final dehy-drated product is generally in the form of pelletswhich can be easily handled.

In the United States, the production of dehy-drated alfalfa increased from 285 MT in 1944-45to over 1,542,650 MT in 1969-70. In early 1970, asudden decline in production occurred primarilydue to competition of foreign producers. Later, thesteady increase of energy cost and new air pollu-tion standards decreased the profit margin in de-hydrating. Many plants were closed and produc-tion fell below 1,181,818 MT.

Wet fractionation of freshly harvested crops canreduce the energy requirement because the pressedforage contains about 50 percent less water to beevaporated per MT of final produce. The latent heatfrom the dryers’ exhaust gases was recycled for usein the evaporation processes, resulting in less airpollution.

(TO WASTE)

The Valley Dehydrating Company (VDC), Ster-ling, Colo. (fig. 13) converted one of their existingplants to Pro-Xan production. The Department ofEnergy (DOE) supported the conversion as a meansof demonstrating the efficient energy conservationpossibilities in alfalfa dehydrators. With this fund-ing, the research efforts of the USDA Western Re-gional Research Center, U.S. Department of Agri-culture at Berkeley, Calif., could be realized in anew LPC production plant in the United States. Theprocess equipment and operating parameters havebeen described in several publications (23,24).

The results of a detailed study of this companyby Edwards, et al. (25), were published as a DOEreport. The exceptionally high level of technologyassociated with this industry can be seen in table11, which shows the considerable cost investmentfor conversion of a conventional 18 MT/hr dehydra-tion plant to a 36 MT/hr Pro-Xan plant. Because ofthis high investment, it would be prohibitive to con-struct a similar factory in the humid tropics withoutprevious extensive studies of available plant mate-rial at the on-farm level,

During the experimental period, the plant oper-ated at 13.6 to 21.8 MT/hr, and produced an average

Leaf Protein Extraction From Tropical Plants • 99— —

Figure 13.—Aerial View of the Valley Dehydrating Co., Sterling, Colo.

LPC yield of 12.8 percent (dry basis). The VDC plantconsumed 25 percent less total energy. Based onthe experience at VDC, future LPC plants are pro-jected to reduce overall energy consumption by 35percent. The VDC products have been marketedreadily; the press cake has been sold to cattlefeeders at a price equivalent to dehydrated alfalfa,and the LPC to a broiler producer at prices vary-ing from $391 to $530/MT. Animal performancetrials using VDC produced products were highlysatisfactory. Projected current cost of a new LPCplant processing 36 MT of chopped alfalfa per houris $4.7 million (table 12); the cost of converting anexisting 18 MT/hr dehydration plant to a 36 MT/hrLPC plant is estimated at $3.6 million. The calcu-lated rate of return on investment for the new plantwas 12.0, 26.2, and 40,4 percent for operatingseasons of 130, 180, and 230 days, respectively(table 13).

The Vepex process was the first large-scale directproduction method for LPC. It was built as a sepa-rate industrial unit not associated with a dehydrat-ing industry. Its primary purpose was to maximize

Photo credit: Courtesy of R. H. Edwards

production of plant protein both for the fodder in-dustry and for human nutrition. The process canalso use raw material other than alfalfa.

Another essential feature is use of the depro-teinized brown juice (33). Some of the nitrogencompounds present in the green juice are not pre-cipitated by heat treatment, The soluble N in thedeproteinized residual brown juice can amount to30 to 40 percent of the total N content in the greenjuice. This can be used as substrate for feed gradeyeast production.

A flow sheet of the Vepex process is shown infigure 14. Vepex plants are located in Denmark andHungary. The plant in Tamasi in southwest Hun-gary is temporarily closed to make energy-savingimprovements,

In Britain, the BOCM-Silcock Co, studied thepreparation of dry leaf protein concentrates on apilot plant level with the aim of creating a systemto provide reasonably priced protein for feed in theform of storable products. The dry matter andpressed crop had to be at least 14 percent, a limitset by the European Common Market (78). The flow

100 . Plants: The Potentials for Extracting Protein, Medicines, and Other Useful Chemicals—Workshop Proceedings—

Table 11.— Basic Equipment Requirements for a ModifiedPro-Xan Plant Processing 36.3 Mg (40 t) of Fresh

Alfalfa Per Hour

j@ Item Specifications No. req’d Total Connectedpower, kW (hp)

Forage harvester/chopper . ,Truck

TruckTruck scaleFeederWet grinderScrew pressHydrasieveSteam injectorCentrifugeDrier, Pro-Xan with

recycle systemPellet mill, Pro-XanBucket elevator, Pro-XanPellet cooler, Pro-XanScalper screen, Pro-XanInventory scale, Pro-XanBucket elevator, Pro-Xanbad-out bin, Pro-XanWaste heat evaporator,

(3 stage, 2 effect)with cooling tower

Drier, press cake withrecycle system

Grinder, dried press cakeBag filter, press cakePellet mill, press cakeBucket ● levator, press cakePellet cooler, press cakeScalper screen. press cakeInventory scale, press cakePneumatic transfer system,

press cakeLoad-out bin, press cakeBoiler, with economizerAir compressor

7Pumps 2Conveyors , wet productTanks, with agitatorsWellHeat exchanger.Waste water treament

self-propelled , 12 ft header22 ton, tandem axle, 34 ftbed , diesel powered.3/4 ton pickup60 ton40 tons/hr10 tons/hrsingle screw, 20 tons/hr6 ft wide3 in. dia.decanter type , 80 gal/rein.triple pass, 6,000 lb H 2O/hr

1-1/2 torls/hr1-1/2 tons/hr1-1/2 tons/hr1-1/2 tons/hr1-1/2 tons/hr1-1/2 tons/hr1280 cubic feet40,000 lb E20/hr

30,000 lb H2O; 185°F

9 tons/hr9 tons/hr9 tons/hr9 tons/hr9 tons/hr9 tons/hr9 tons/hr9 tons/hr

3328 cubic feet400 boiler horsepower36 SCFMvarious , to 200 gpmvarious, to 40 tons/hrvarious , to 10,000 gal.250 gal/rein600 sq . ft. , shell and tubeunspecified

4

421

141221

11111121

1

11111111

4116

12611. .

29.8 (40)298.4 (400)179.0 (240)

— --

85.8 (115)44.8 (60)

30.6 (41)1.5 (2)

11.7 (15-3/4)0.4 (1/2)— --

1.5 (2)— --

173.1 (232)

122.3 (164)

224.9 (301-1/2)23.5 (31-1/2)

233.1 (312-1/2)2.2 (3)

30.6 (41)0.4 (1/2)

23.5 (31-1/2)

41.0 (55)7.5 (lo)

31.7 (42-1/2)55.6 (74-1/2)

3 .4 (4 -1 /2)14.9 (20)

37.3 (50)

Tot al 1708.5 (2290.25)

~/ Not applicable..

~/ Does not inclued pumps in evaporator installation.

SOURCE: Edwards, et al. (25).

Leaf Protein From Tropical Plants ● 101

Table 12.—lnvestment Costs for a Revised Pro-XanPlant with a Capacity of 36.3 Mg (40 t) of

Chopped Alfalfa Per Hour

I t e m I n v e s t m e n t C o s t ,d o l l a r s

E q u i p m e n t , h a r v e s t i n g a n d h a u l i n g 5 0 4 , 4 0 0 .Equipment p r o c e s s p l a n t 2 , 7 9 3 , 3 4 9 ”B u i l d i n g s 2 8 2 , 5 0 0L a n d 3 4 6 , 8 0 0E n g i n e e r i n g a n d i n s t a l l a t i o n c o s t4 1 , 1 1 7 , 3 4 0

T o t a l 4,744,389

1 Based on May 1982 p r i c e s .2 B u i l d i n g s i n c l u d e space fo r a l l o p e r a t i o n s e x c e p t l o n g t e r m b u l k

s t o r a g e w h i c h i s t r e a t e d s e p a r a t e l y .3 Six acres4 Assumes 40 percent of cost of p r o c e s s p l a n t e q u i p m e n tSOURCE. Edwards, et al (25)

Table 13.—Annual Operating Costs, Revenues, and Return on lnvestment for the Revised Model Pro-Xan Plant

c o s t (dollars) at season length ( d a y s )

Item 130 180 230

Annual RevenuesD e h y d r a t e d p r e s s c a k eP r o - X a n

T o t a l R e v e n u e s

Annual CostsA l f a l f a , raw materialChemicalsNatural g a sE l e c t r i c i t yFuel and o i lMaintenance and repairsLaborAdministrationProperty taxesInsuranceI n t e r e s tDepreciationStorage costsMarketing costsTransportation costs

T o t a l c o s t s

Total e a r n i n g s

Total Investment

Annual return on investment (%).

2,645,2611,803,0234,448,284

7 6 6 , 4 8 06 0 , 1 2 6

5 1 6 , 6 6 31 7 7 , 6 6 31 3 1 , 5 6 04 0 7 , 9 2 31 8 2 , 5 2 071,10019,92654,676

499,491336,317143,16273,626

436,3043,877,537

570,747

4,744,389

1 2 . 0

3,662,6692,496,4946,159,163

1,061,28083,251

715,377245,995182,160451,923252,72071,10019,92654,676

537,027336,317198,225101,944604,113

4,916,034

1 , 2 4 3 , 1 2 9

4 , 7 4 4 , 3 8 9

2 6 . 2

4 , 5 8 0 , 0 7 83 , 1 8 9 , 9 6 47 , 3 7 0 , 0 4 2

1 , 3 5 6 , 0 8 01 0 6 , 3 7 79 1 4 , 0 9 43 1 4 , 3 2 72 3 2 , 7 6 04 9 5 , 9 2 33 2 2 , 9 2 0

7 1 , 1 0 01 9 , 9 2 65 4 , 6 7 6

5 7 4 , 5 6 33 3 6 , 3 1 72 5 3 , 2 8 71 3 0 , 2 6 17 7 1 , 9 2 2

5 , 9 5 4 , 5 3 3

1 , 9 1 5 , 5 0 9

4 , 7 4 4 , 3 8 9

4 0 . 4

1 plant capacity 36.3 ).& (40 t o n s ) c h o p p e d a l f a l f a ( 2 2 p e r c e n t d r y utter) per h o u r .

SOURCE:Edwards, et al.(25)

102 ● Plants: The Potentials for Extracting Protein, Medicines, and Other Useful Chemicals—Workshop Proceedings

Figure 24.—Material Flow in Vepex Process

FLUE GAS

1

DRYER

84,0 Kg I

GREEN

PROTEIN GONG.

SOURCE: Koch (48).

sheet of this LP fractionation processfigure 15.

STEAM

is shown in

‘When the full-scale plant was built, it required agrowing area of 480 ha within an 8-km haulage ra-dius. To operate at full capacity, the plant had an-ticipated producing lye-treated straw in the idleseason. However, the straw feed was not accept-able in Britain, and the new plant was shut downafter a brief interval of operation because the shortproduction period made it inefficient to operate(79).

In New Zealand, Alex Harvey Industries, Ltd., incooperation with the Ministry of Agriculture andFisheries and the Broadlands Lucerne Company,is planning to establish a plant to produce a leafprotein concentrate with 47 to 50 percent crudeprotein content and high levels of xanthophyll andcarotene pigments. This will be used for poultryfeeding, A high fiber pellet for ruminant stock willalso be produced. The plant will have a capacity

of 10 MT/hr of green alfalfa and be operated bygeothermal steam (67).

Two pilot plants managed by agricultural coop-eratives began operation in Japan in 1981. E a c hprocesses 2.7 MT/hr of fresh herbage. One of themhas facilities to separate LPC by centrifugation, con-dense green juice by reverse osmosis, condensebrown juice by heating, cultivate yeast using brownjuice, and make water from fibrous residue (58).

Preparation of Colorless EdibleProteins From Alfalfa

The processing of LPC to obtain a food-gradeproduct was reviewed by Bray (12). Green LPC canbe produced economically. However, some prob-lems exist in human acceptance of protein concen-trate prepared by heat precipitation at 820 C: itsgreen color, grassy flavor, and low volubility,

Leaf Protein From Tropical Plants ● 103

Figure 15.—The BBOCM-Slicock Green CropFractionation Process

SOURCE Thrlng (78)

A step in preparing improved protein in largerquantities by solvent extraction has been reported.Ineritei (38) found that freshly prepared coagulumcould be decolonized with an acetone and isoprop-anol mixture. The treatment improves flavor andtexture and gives a prolonged shelf life to the lightcream-colored product by removing the lipids. Thelipid distribution in green LPCs prepared from fourtropical plants was analyzed by Nagy, et al. (55).The sale of lipid components, especially xantho-phyll and B-carotene, and solvent recovery withsolar power in the tropics could decrease the costof this process.

Solvent extraction does little to improve the nutri-tional value of LPC. The tannin-damaged leaf pro-tein concentrates are not or are only slightly im-proved nutritionally, Only a small amount of ad-sorbed tannins can be removed (Ii’).

In the heat fractionation process, after isolationof the green protein at 55° C, in many plants twoadditional white protein fractions can be separated:one at 64° C and another at 820 C (77). The whiteprotein fraction prepared from alfalfa is nutritious,with a protein efficiency ratio (PER) similar to thatof casein (9).

The heat coagulated proteins are practically insol-uble. It was suggested that they could be used insoups, gravies, cheese, and cookies (7). Food tech-nologists for industrial application require certainfunctional properties for proteins. If leaf proteinscould be processed to possess the desired proper-ties, they would have wider use in the foodindustry.

Since solvent extraction of undried green proteinhas been costly and only partially effective and thewhite protein prepared by heat precipitation is in-soluble, radically different and more complex pro-cedures for producing soluble white and bland-tasting protein have been initiated.

In diafiltration, water is added to clarified alfalfajuice during ultrafiltration so that small molecularweight components can be washed through a mem-brane. On a laboratory scale, diafiltration, after amild heat treatment and centrifugation for clarifica-tion, resulted in a freeze-dried product that wascream-colored and highly water soluble (46).

Pilot-scale ultrafilter units were tested by Knuck-les, et al. (44) for concentrating and purifying solu-ble alfalfa leaf protein solutions after coagulatingthe protein at 60” C. Operating temperature wasgenerally maintained at a low 100 C to avoidmicrobial growth and precipitation of the heatlabile protein. The clarified alfalfa juice was con-centrated to one-tenth of original volume, produc-ing protein concentrates containing about 50 per-cent crude protein and 10 percent ash. Using dia-filtration, water was added to the concentratedalfalfa juice until the permeate volume was 10 timesthe original sample volume. This method resultedin material containing 70 to 76 percent protein,Dried protein products were tan colored despite theremoval of more than 86 percent of the ortho dihy -droxy phenolic compounds.

The ultrafiltration systems tested by Knucklesand his coworkers cannot produce light cream-colored protein concentrates of greater than 90 per-cent purity. Because of their high cost and ineffec-tiveness, they are not viable methods for large-scalepurification of alfalfa protein.

Flocculants are used to remove suspended solidsfrom solution, Knuckles, et al. (47) reported theirwork with 54 commercial flocculants tested to im-prove the separation of the green chloroplastic pro-tein fraction from alfalfa juice. With a l-percentlevel of cationic flocculent, the chloroplastic frac-tion was separated by continuous high-speed cen-trifugation. Residual sediment was less than 0.5percent; however, the processing rate was low(11.41/min). This technique also proved to be effec-tive as pretreatment in membrane filtration. The

104 . plants: The Potentials for Extracting Protein, Medicines, and Other Useful Chemicals—Workshop Proceedings

treated juice yielded greater soluble protein contentthan the untreated control,

Knuckles and Kohler (43) prepared soluble leafprotein concentrates (light tan colored). Accordingto the authors, these should be acceptable as a foodsource. However, no cost data is given. Gel filtra-tion was previously used for fractionation of LPCby Fishman and Burdick (29) in characterization ofprotein of Coastal Bermuda grass proteins. The useof filter gels such as Sephadex is costly in even an-alytical processes. Freeze-drying is also a very ex-pensive process because the special equipment isexpensive and requires high energy input. Specialproteins such as active enzymes may be preparedby this method for biochemical or medicinal pur-poses. Comparing quality and price, the proteinsseparated by gel filtration cannot compete with theFraction I protein of tobacco, which can be pre-pared by crystallization and is water soluble. Dr.Wildman will discuss this unique protein in com-plete detail.

Environmental and Cultural Aspects

Nature and tradition have created richly variablecultures in tropical areas. It is difficult to designa general plan for a leaf protein extraction systemfor the entire tropical zone. It is evident that thewhole system has to be geared to the natural andcultural local environment: the climate, physicallocation, soil fertility, and local cultural habits.Two-product use is a key to the viability of the LPCprocess. Ruminants must remain in the chain ofprotein production to use the pressed residue. Incountries such as India, dairy animals or goats willbe used on a smaller scale operation than that in-volving beef cattle in developed countries. Thegreen LPC could be fed to humans or to calves asa milk replacement, saving milk for human con-sumption. In Islamic lands, cattle, lambs, goats, andrabbits could be fed the pressed residue, andchickens and ducks the green concentrate. In LatinAmerica, the green juice could be fed to pigs andchickens, and the pressed residue to beef or dairycattle.

The increasing protein shortage in the tropicscannot be alleviated effectively by village scale pro-duction of LPC, especially if it is used only for in-fant feeding. At the First International Conferenceon Leaf Protein Research held recently in Auran-gabad, India, there were arguments regarding in-fant feeding trials between the representative of thebilateral and multilateral donor agencies and therecipient of grants for a children’s feeding trial on

one side and a highly respected local scientist onthe other. The scientist claimed that “There is nodoubt that leaf protein is good for protein andcarotene nutrition. But its use in children feedingtrials is considered unethical, purposeless, and un-scientific. It is argued that the scope of thepigmented leaf protein in food is limited to the in-dividual family or to communities of no social andeconomic disparities, Its production and use as ameans for overcoming the protein and carotene de-ficiency in human nutrition is not a practical prop-osition” (70).

Advocates of infant feeding claim that infants re-spond favorably to feeding formulas containingalfalfa LPC. This claim could be contested. A pro-tein-depleted infant would respond rapidly to anyproteinous feeding. The effect of prolonged infantor child feeding of crude alfalfa green protein hasnot been properly evaluated. The following factsare disturbing. It is well documented that saponinsof alfalfa impede the growth of chicks (16). Its tan-nin-phenol complexes are not digestible; their inter-action with digesting enzymes of infants can bedamaging, The biologically active coumestrol pres-ent in alfalfa was found in leaf protein concentrate(45). In the growth of children, the possibility of illeffects caused by the physiologically active ingre-dients of alfalfa green protein after prolonged feed-ing must be recognized. The dietetical value of thetouted laddu, a product of high sugar content, alsoremains questionable. The large sum of researchmoney spent did not produce basic data on possi-ble long-term undesirable effects of the use of alfalfaLPC and did not reduce substantially the ever-increasing number of ill-fed children,

LPC as an emergency food for humans, as wassuggested by Pirie for England during World WarII, should be considered, Experimentally, it hasproven to be nutritious; however, the author isagainst human use of LPC, especially that of alfalfa,because of incomplete testing and the possiblepresence of antinutritional factors. The small-scaleproduction of LPC should not be rejected entirely.In extreme poverty, it could be incorporated as aprotein source into native dishes. However, forhuman consumption of LPC, plants should be se-lected from local green leafy vegetables such as col-lard, mustard green, and other brassicas.

Pirie (63) suggested at the Belo Horizontemeeting in Brazil: “Except for infant feeding,nothing could be gained by extracting protein fromleaves that can be eaten as green vegetables. Thebest way to use LP to improve the nutrition of un-weaned infants is to give it to the mother ratherthan the infant, A broad-minded approach to bot-

Leaf Protein From Tropical Plants . 105

any is needed; the present occupation with alfalfais unfortunate. ”

Advocates for LPC feeding for children cite theimportance of carotenoids in diets of ill-fed chil-dren. LPC could supply these but carrots, tomatoes,and green leafy vegetables could also supply chil-dren with the needed carotene.

It is obvious that a farm’s topography and sizewill be decisive factors in determining its abilityto produce LPC. Small hamlets and subsistencefarms will not be able to participate in LPC produc-tion, On small farms in the mountainous areas ofthe tropics, pods of winged beans and leafy vege-tables such as collards, mustard greens, amaran-thus, or even spinach could be additional sourcesof proteins and carotenes to supplement the fami-ly’s daily consumption of beans and corn. Bananasor plantains, cassava, or yams are staples in suchareas. It is difficult to believe that the wife of astruggling farmer in the Tropics will harvest leaves,pound them, filter the juice, and prepare a coagu-lum for food. Alternate sources of protein might bemore acceptable to the low-income farmer. For ex-ample, the breeding of rabbits could be popularizedon small farms. Harris, et al. (30), proved that driedtropical leaves, even those of cassava which are un-

Figure 16.— Screw Press

fit for LPC production, supported the growth of rab-bits and gave good results.

In a proper leaf protein preparation process, allproducts must be effectively used and not wasted.Since deproteinized juice cannot be used in smallvillage units for yeast production, it should be usedto irrigate fields. The fractionation process to whiteproteins would be a prolonged procedure withsmall yield for feeding trials. Similarly, the use ofcomplicated purifications by ultrafiltration and gelfiltration would be impractical.

The quality of life in rural areas of less developedcountries has to be raised; however, a single, smallindustry like the bicycle-driven LPC production sys-tem used in India and involving a $3,000 invest-ment will not substantially help alleviate the prob-lems (fig. 16),

More moral and material support should be givento the plan of Joshi (41), which is a healthy transi-tion to the on-farm use system. He suggested thatin India LPC production could be incorporated intoa small, cooperative dairy farm to improve animalhusbandry for selected cows and to increase milkproduction, This would be practical, Dairy coop-eratives are being used successfully in Europe,where the milk is collected for central processingand distribution.

Operated by Human Powerin India

Photo credit: Courtesy of R. J. Joshi

24-503 0 - 83 - 8

106 • Plants: The potentials for Extracting Protein, Medicines, and Other Useful Chemicals— Workshop Proceedings

The on-farm use system has been studied onlywith alfalfa and ryegrass. Using legumes, thesemodel experiments could be duplicated in tropicalcountries, especially in Latin America where agri-cultural practices are well developed, land is avail-able, and relatively simple technology could be suc-cessfully adapted to individual needs. The introduc-tion of this type of system into areas of sugarcaneproduction would reduce the acreage given to thatcrop, an economically sound decision, There is thepossibility of substituting leaf protein for high pro-tein feeds, such as soybean meal, in poultry and hogprotein rations which are now imported into trop-ical areas.

As discussed in the on-farm use section, a pro-duction system of medium capacity is probably thelevel that will have a tangible effect on the proteinresources within an area without disturbing its en-vironment. There is no waste; the animal manurecan be returned to the fields to improve the soil,and some of the pressed juice can be used for ir-rigation. The production facilities could processplant material contracted from neighboring farm-ers. A higher income level would result from moreintense agriculture, which easily could be adaptedto the existing conventional system. This size ofagro-industry will not put a strain on electricity.The processing machinery could use small tractorsas a source of power, It will not require a largeamount of water, and only simple tools are neededfor maintenance.

Research Needed

Leaf protein fractionation would increase the pro-tein production of a given area universally. Thebasic farm equipment has been designed and prop-erly evaluated, and existing machinery can proc-ess any fresh green crop with proper N level andextraction. The production level should be selectedaccording to the needs of an ecosystem and modi-fied according to the traditions and religious biasof the local population. Suitable plants should bestudied in more detail, possibly using a medium-scale experiment at the production site. However,before expansion to the Pro-Xan type of operationcan be contemplated, it is imperative that long-range studies be made of potential plant materialat the on-farm use level.

USDA research centers and U.S. land-grant uni-versities and tropical research centers in developedcountries should have sufficient funds for the re-maining basic and applied research needed for LPCextraction. An international cooperation between

U.S. institutions and host institutions funded byAID should be developed for applying the researchresults in countries in the Western Hemisphere thatwould benefit from agricultural development basedon LP extraction. A parallel program should enablescientists from host countries to learn the chemicaland physical methods of production and qualitycontrol of raw material and finished products.

The host country scientists would offer the neces-sary data required for successful implementation.The following salient points must be carefully in-vestigated by local scientists before a system andsite are chosen:

1. Market research to determine need and ac-ceptance of products

2. Availability of suitable land3. Likelihood of undisturbed flow of plant

material for processing.The next phase of investigation should be nutri-

tional evaluation of LPC products with large andsmall animals: cattle, milk cows, goats, rabbits, pigs,and chickens, The preparation of proper feed mixesshould not be neglected. It is not sufficient toprepare a nutritionally balanced feed mixture; itshould be readily acceptable by the animal andshould have good keeping qualities,

Farm-level processing machinery has been welldesigned for disintegration and pressing. Only thatused for the separation of green protein concentrateneeds more investigation to obtain simpler andmore effective equipment. An inexpensive basketcentrifuge would probably be useful in this step ofthe process,

Well organized on-farm use of LPC could providea thorough evaluation of tropical plants using me-dium-size technology and pave the way for the de-velopment of large-scale production of LPC—espe-cially in tropical countries where advanced tech-nology and sufficient amount of capital are avail-able, such as Brazil, Puerto Rico, and Venezuela.After evaluation of plant sources on a farm scale,a commercial-size production facility is more like-ly to succeed.

While the capital requirements for large-scaleproduction are high, the return on investment isalso likely to be high because of the low labor costsand year-round operating season. The effect of thelength of the operating season on return on invest-ment is illustrated in table 13. The use of govern-ment subsidies to set up cooperative, commercial-scale plants might help initiate the new industry(26). Additional research funds should also be allo-cated to study low cost, more efficient extraction,dewatering, separation, and evaporation tech-

Leaf Protein From Tropical Plants . 107

niques that are suitable for large-scale LPC produc-tion from tropical plants studied previously andselected from intermediate-size studies.

Acknowledgment

The author is indebted to Professor EmeritusHjalmar D. Bruhn and Dr. Richard H, Edwards fortheir guidance, data, pictures, and final reviewingof the manuscript; Dr. Richard G. Koegel for a day-long conference at the University of Wisconsin onthe machinery of an onfarm use system; Dr. WalterJ. Bray for permitting the use of economic evalua-tion data of village level production of LPC in In-dia, and N. W. Pirie for pictures of machinery de-veloped at the Rothamsted Experimental Station,Harpenden, England. Only with their prompt andvaluable assistance could I have written an up-to-date report on the present status of LPC extractionin the Tropics and project a positive, progressiveplan for its future.

1. Ajibola, O. 0., Straub, R. J., Bruhn, H. D., and Koegel,R. G., “Fermentation of Plant Juice as a ProteinSeparation Technique,” ASAE Paper No, 81-1528,ASAE, St. Joseph, Mich., 1981,

2. Anelli, G., Fiorentini, R., Massignan, L., and Galop-pini, C., “The Poly-Protein Process: A New Methodfor Obtaining Leaf Protein Concentrates, ” ]. FoodSci., 42(5):1401, 1977.

3. Anonymous, news item, “Alfa-Laval France Sold TwoLPC Factories to U. S. S.R., ” Industries Alimentationet Agricoles, ” 94:84-85, 1982.

4. Bacon, J. S. D., “Extraction and Use of Juice fromLucerne and Grass, presented at National Institutefor Research in Dairy ing, ” mimeographed NIRD,Shinfield, England, 1974.

5. Basken, K. E., “Principles of Rotary Forage Macer-ator Design, ” unpublished MS Thesis, University ofWisconsin-Madison, 1975

6. Basken, K. E., Shirer, D. K., Koegel, R. G., and Bruhn,H. D., Reducing the Energy Requirements of PlantJuice Protein Production, TRANSACTIONS of theASAE, 20(6):1050-1056,1977.

7. Betschart, A. A., and Kohler, G. O. “Certain Func-tional Properties of Alfalfa Protein Isolates Preparedand Dried by Various Methods, ” Proc. 12th Techn.Alfalfa Conf., Berkeley, Calif., 1975, pp. 115-122.

8. Bickoff, E. M., and Kohler, G. O. “Preparation of Edi-ble Protein from Leafy Green Crops Such as Alfal-fa,” U.S. Patent No. 3,823.128, July 9, 1974.

9.

10.

11.

12.

13,

14.

15,

16,

17.

18.

19.

20.

21.

22.

Bickoff, E. M., Booth, A. N., de Fremery, D., Edwards,R. H., Knuckles, B. E., Miller, R. E., Saunders, R. M.,and Kohler, G. O., “Nutritional Evaluation of AlfalfaLeaf Protein Concentrate, ” Protein Nutritional Quali-t~ of Food and Feeds, M. F. Friedman (cd. ) (NewYork: Marcel Dekker, 1975), pt. 2, pp. 319-340.Bickoff, E. M,, de Fremery, D., Edwards, R. H.,Knuckles, B, E., Kohler, G. O., and Miller, R. C.“Preparation of Soluble Edible Protein From LeafyGreen Crops, ” U.S. Patent No. 3,959.246.1, May 25,1976.Braude, R., Jones, A. S., and Houseman, R. A. “TheUtilization of the Juice Extracted From Green Crops, ”in Green Crop Fractionation, R. J. Wilkins (cd.),British Grassland Society and British Society ofAnimal Production, 1977,Bray, W. J., “The Processing of Leaf Protein to Ob-tain Food-Grade Products, ’’Green Crop Fractionation,R. J. Wilkins (cd.), British Grassland Society andBritish Society of Animal Production, 1977.Bray, W. J., “A Study of the Cost of Producing LeafProtein Concentrate in an 1ndian Village Operation, ”Meals for Millions/Freedom From Hunger Founda-tion, Santa Monica, Calif., 1980.Bruhn, H. D., Straub, R. J., and Koegel, R. J. “GreenPlant Juice Protein Extraction Research at the Univer-sity of Wisconsin- Madison,” paper presented at in-ternational Conference on Leaf Protein Research,Marathwada University, Aurangabad, India, Oct. 5-8,1982.Carroad, P, A., Anaya-Serrano, H., Edwards, R. H.,and Kohler, G. O., “Optimization of Cell Disruptionfor Alfalfa Leaf Protein Concentrate (Pro-Xan) Pro-duction,” ~. Food Sci., 46(2):383-386, 1981.Cheeke, P. R., “Biological Properties and NutritionalSignificance of Legume Saponins, ” Leaf Protein Con-c e n t r a t e s , L. Telek and H. D, G r a h a m (eds. ),(Westport, Corm.: AV1 Publishing Co., 1983.)Cheeke, P. R., Telek, L., Carlsson, R., and Evans, J,J., “Nutritional Evaluation of Leaf Protein Concen-trates Prepared From Selected Tropical Plants, ”Nutrition Reports International, 22:717, 1980.Davys, M. N. G., “An Outline of the Asian TourU n d e r t a k e n for Find Your Feet” personal com-munication, 1981.Davys, M. N, G., and Pirie, N. W. “Protein FromLeaves by Bulk Extraction, ” Engineering, 190:274,1960.Davys, M. N. G., and Pirie, N. W. “A Belt Press forSeparating Juices From Fibrous Pulps,” ]. Agric. Eng.Res., 10:142, 1 9 6 5 .Devadas, R. P,, Kamalanathan, G. and Vijayalakshi,P. “The Coimbatore Leaf Protein Feeding Trial, ”abridged report, Find Your Feet, London, 1978.Edwards, R. H., de Fremery, D. and Kohler, G. O.“The Pro-Xan Process, Production of Leaf ProteinFrom Alfalfa, ” Twelfth Technical Alfalfa ConferenceProc., USDA Western Regional Research Center andAmerican Dehydrators Association, Berkeley, Calif.,1975, pp. 67-71.

108 “ Plants: The Potentials for Extracting Protein, Medicines, and Other Useful Chemicals—Workshop Proceedings

23.

24.

25.

26,27.

28.

29,

30.

31.

32.

33.

34,

35.

36.

37,

Edwards, R. H., Miller, R. E. and Kohler, G. O. “Com-mercial Scale Production of Alfalfa Leaf Protein Con-centrate, ” Paper No. 81-1524, winter meeting, Amer.SOc. Agr. Eng., Chicago, Ill., Dec. 15-18, 1981.Edwards, R. H., Miller, R. E,, Kohler, G. O., andMcDonald, D. R., “Commercial-Scale Production ofAlfalfa Leaf Protein Concentrate (Pro-Xan): A Prog-ress Report, ” Paper No. 79-6533, winter meeting,Amer. Soc. Agr. Eng., New Orleans, La., Dec. 11-14,1979.Edwards, R. H,, Kohler, G. 0,, Miller, R. E., Lyon,C. K. and Kuzmicky D. D., “Wet Fractionation ofForage to Reduce Energy Requirements of Dehydra-tion,” Report No. DOE/CS40090, National TechnicalInformation Service, Springfield, Va., 1982.Edwards, R. H., personal communication, 1982.Enochian, R. V,, Edwards, R. H., Kuzmicky, D. D.,and Kohler, G. O., ’’Leaf Protein Concentrate (Pro-Xan) From Alfalfa: An Updated Economic Evalua-tion, ” Paper No. 79-6538, 1977 winter meeting, Amer.Soc. Agr. Eng., Chicago, Ill., Dec. 13-16, 1977.Enochian, R. V., Kohler, G. O., Edwards, R. H., Kuz-micky, D. D., and Vosloh, C. J.,Jr., “Producing Pro-Xan (Leaf Protein Concentrate) From Alfalfa:Economics of an Emerging Technology, ”Agricultural Economic Report No. 445, U.S. Depart-ment Agric., 38 pp., 1980.Fishman, M. L., and Burdick, D. Extractability,Volubility, and Molecular Size Distribution ofNitrogenous Constituents in Coastal Bermuda Grass,.J. Agric. Food Chem., 25:1122-1127, 1977Harris, D. J., Cheeke, P. R., Telek, L., and Patton, N.M., “Utilization of Alfalfa Meal and Tropical Foragesby Weanling Rabbits,” Proceedings, vol. 31, WesternSection, American Society of Animal Science, 1980.Hibbs, J, W., Conrad, H. R., and Johnson, W. H.,“Macerated and Dewatered vs. Wilted Alfalfa GrassSihige for Dairy Cows, ” Ohio Res. Dev. Center. Res.Bu]. 1013, 1968.Hello, J. and Koch, L., “Protein From Green Matter. ”Process Biochem. 5(10):37-39, 1970.Hello, J,, Zagyvai, I., and Koch, L., Process for theProduction of Fiberless Green Plant Concentrate ofFull Biological Value,” U.S. Patent No. 3637.396, Jan.25, 1971.Houseman, R. A., and Connell, J. “The Utilization ofthe Products of Green-Crop Fractionation by Pigs andRuminants,” Proc, Nutr. Soc., 35:213, 1976.Houseman, R. A., Jones, A. S., Innes, G, M, and Col-lier, R., “The Production of Carcass Meat From Cat-tle and Pigs Utilizing the Products of Grass Fractiona-tion, ” Proceedings of the British Society of AnimalProduction, 4:107, 1975.Hove, E. L., and Bailey, R. W., “Towards a Leaf Pro-tein Concentrate Industry in New Zealand,” AMemorial to Dr. Russel M. Allison, N. Z. J. Exp.Agric., 3:193-8, 1975.Huang, K. H., Tao, M. C., Boulet, M., Riel, R. R.,Julien, J. P., and Brisson, G. J. “A Process for thePreparation of Leaf Protein Concentrates Based on

38.

39.

40.

41.

42

43.

44.

45.

46.

47,

48,

49.

50.

51.

52.

the Treatment of Leaf Juices With Polar Solvents,”Can. Inst. Fd. Techno]. 4(3):85, 1971.Ineritei, M. S., “The Effects of Solvents on the Prop-erties of LPC, ” M. SC, Thesis, University of Reading,England, 1976.Jones, A. S., “A Report of the Joint ScottishAgricultural Development Council, Rowett ResearchInstitute and North of Scotland College of AgricultureDevelopment Programme on Grass Fractionation,”in Green Crop Fractionation, R. J. Wilkins (cd.),British Grassland Society and British Society ofAnimal Production, 1977.Jones, A. S., Macleod, A. S., Macdearmid, A., andHouseman, R. A., “The Value of Grass Pulp for Ru-minants,” Proceedings of British Society of AnimaZProduction 3:113-116, 1974.Joshi, R. N., “Fractionation of Green Plants onMarathwada Dairy Project, ” NaturaZ Sciences Jour-naZ, Marathwada University, Aurangabad XV 67-73,1976.Joshi, R. N., Savangikar, V. A., and Patunkar, B. W.,“Production of Leaf Protein in an Indian Village—Prospects and Problems,” paper presented at the In-ternational Conference on “Frontiers of Research inAgriculture, ” Indian Statistical Institute, Calcutta,India, Sept. 30, 1982.Knuckles, B. E., and Kohler, G. O., “Gel FiltrationChromatography of Protein Extracts From Alfalfa, J.Sci. Food Agric. 33:128-132, 1982.Knuckles, B. E., de Fremery, D., Bickoff, E. M.,Kohler, G. O . , “Pilot Scale of Ultrafiltration ofClarified Alfalfa Juice,” J. Food Sci. ” 45:730-734, 739,1980.Knuckles, B. E., de Fremery, D., and Kohler, G. 0.,“Coumestrol Content of Fractions Obtained DuringWet Processing of Alfalfa,” J. Agric. Food Chem.,24:1177, 1976.Knuckles, B, E., de Fremery, D., Bickoff, E. M.,Kohler, G. O., “Soluble Protein From Alfalfa Juice byMembrane Filtration,” J, Agric. Food Chem. 23:209-212, 1975.Knuckles, B. E., Edwards, R. H., Kohler, G. O., andWhitney, L. F., “Flocculants in the Separation of Solu-ble White Protein Fractions From Alfalfa,” J. Agric.Food Chem. 28:36-39, 1980.Koch, L., “The Vepex Process,” in Leaf Protein Con-centrates, L. Telekand, H. D. Grham (eds.) (Westport,Corm.: AVI Publishing Co., 1983), pp. 601-632.Koegel, R. G., and Bruhn, H. D., “Energy Economicsof Alfalfa Juice Protein, ” TRANSACTIONS of theASAE, 21:605-609, 1978.Koegel, R. G., V. I. Fomin, and Bruhn, H. D., “CellRupture Properties of Alfalfa,” TRANSACTIONS ofthe ASAE, 16:712-716, 1973.Koegel, R. G., Gehling, S. C., Krenke, J. H., Rosek, R.J., Livermore, D. F., and Bruhn, H. D., “Design fora Cone Press for Macerator Expression From PlantMaterials. ASAE Paper No. 78-1527 (St. Joseph,Mich., ASAE, 1978).Kohler, G, O., Wildman, S. G., Jorgensen, N. A.,

Leaf Protein From Tropical Plants . 109

Enochian, R. V., and Bray, W., J., Protein Resourcesand Techno]og~’: Status and Research Needs, M .Milner, N. S. Scrimshaw, and D. 1, C. Wang (eds.)(Westport, Corm.: AVI Publishing Co., 1978), pp.543-568.

53. Kuzmicky, D. I)., and Kohler, G. O., “NutritionalValue of Alfalfa Leaf Protein Concentrate (Pro-Xan)for Broilers, ” Pou)try Sci., 56:1 510-1516, 1977.

54. Little, E. L., and Wadsworth, F, H., “Common Treesof Puerto Rico and the Virgin Islands, ” vol. 1. Agric,

55

56

57

58

59

Handb. 249 (Washington, D. C.: U.S. Department ofAgriculture Forest Service, 1964).Nagy, S., Nordby, H. E., and Telek, L., “LipidDistribution in Green Leaf Protein Concentrates FromFour Tropica l Leaves , ” J. Agric. Food Chern.26:701-706, 1978.Nelson, F. W., Barrington, G. P., Araub, D. R., andBruhn, H. D., “Design Parameters for Rotary Extru-sion Macerators, ” ASAE Paper No. 81-1525, (St.Joseph, Mich.: ASAE, 1981).Nelson, F. W., Bruhn, H. D., Koegel, R. G., and Straub,R. J., “Rotary Extrusion Devices, ” TRANSACTIONSof the ASAE, 23:1587-1599, 1980.Ohshima, M., and Ueda, H., “Pilot Green Crop Frac-tionation Plant in Japan and Nutritive Value of Prod-ucts in Pig and Rat, ” paper presented at InternationalConference on Leaf Protein Research, MarathwadaUniversity, Aurangabad, India, Oct. 5-8, 1982.Ostorwski-Meissner, H. T., “Pasture Production inProtein Extraction System, ” Proc. N. Z. Soc. Anim.Prod. 36:31-41, 1976.

60. Pirie, N. W., “Food From the Forest, ” New Sci. 40:420-422, 1968.

61. Pirie, N. W., “The Machinery for LPC Production, ”in Leaf Protein: Its Agronomy, Preparation, Qua)ityand Use, N.W. Pirie (cd.). International Biologica) Pro-gram Handbook No. 20, (Oxford, United Kingdom:Blackwell’s Scientific Publishers, 1971) pp. 56-62.

62. Pirie, N. W., :“ A Simple Unit for Extracting Leaf Pro-tein in Bulk, ” Expl. Agric., 13:1 13-118, 1977.

63. Pirie, N. W., “Appropriate Leaf Protein Technology.”Proceedings of International Workshop on the Utiliza-tion of Agricultural Waste for Feed and Food, MinasGerais, Belo Horizonte, Brazil, December 1977.

64. Pirie, N. W., “Some Controversial Aspects of Leaf

65

66

Protein Research. ” presented at first InternationalConference on Leaf ‘Protein Research, MarathwadaUniversity, Aurangabad, India, Oct 5-8, 1982.Rouelle, H. M., “Observations on the Fecules orGreen Parts of Plants, and on Glutinous or Vegeto-Animal Matter, ” J. Med. Chir. Pharm. 40:59, Englishtranslation in N. W. Pirie, Leaf Protein and OtherAspects of Fodder Fractionation, (Cambridge, UnitedKingdom: Cambridge University Press, 1973).Shah, F. H., “Protein for Human, Monogastric andPolygastric Animals from Forages in Pakistan, ” paperpresented at International Conference on Leaf Pro-tein Research, Marathwada University, Aurangabad,India, Oct. 5-8, 1982.

67

68.

Shearer, G. J., “Commercialization of Leaf Protein Ex-traction in New Zealand, ” presented at First Inter-national Conference on Leaf Protein Research,Marathwada University, Aurangabad, India, Oct. 5-8,1982.Shepperson, G,, Connell, J., Houseman, R. A., and

Heath-, S. B., ’’The Performance of the Machinery atPresent Available for the Expression of Juice FromForage Crops, ” Green Crop Fractionation, R. J.Wilkins (cd,], British Grassland Society and BritishSociety of Animal Production, Hurley, Maidenhead,England, 1977.

69. Singh, N., “Proteolytic Activity of Leaf Extracts, ” ].Sci. Fd, Agric., 13:325, 1962.

70. Singh, N., “Perspectives in Leaf Protein Research, ”Presented at First International Conference on LeafProtein Research, Marathwada University, Aurang-abad, India, Oct. 5-8, 1982.

71, Sotomayor-Rios, A., and L. Telek, “Forage Yield andProtein Content of Millo Blanco (Sorghum bico]or)and Two FI Hybrids, ” J. Agric. Univ. P. R., 61:300-304,1977.

72. Stahmann, M, A., “Anaerobic Fermentation for Co-agulation of Plant Juice Protein” paper presented atthe Cento Symposium on Biological Conversion ofAgro-Industrial Wastes Into Feed, Lahore, Pakistan,1978.

73. Straub, R. J., and Koegel, R. G., “Evaluation of a ConePress for Forage Fractionation,” ASAE Paper No.81-1527, ASAE, St. Joseph, Mich., 1981.

74. Straub, R. [., Bruhn, H. D., and Barrington, G. P.,“Plant Juice’ Protein Separation and Recovery,” ASAEPaper No. 79-531, ASAE, St. Joseph, Mich., 1979.

75. Straub, R. J., Basken, K. E., Koegel, R. G., and Bruhn,D. H., “Instrumentation and Controls for AutomatedPlant Juice Protein Concentrate Production,” TRAN-SACTIONS of the ASAE, 20:649-652, 1977.

76. Straub, R, J., Tung, J. Y,, Koegel, R. G., and Bruhn,H. D., Drying of Plant Juice Protein Concentrates,”TRANSACTIONS of the ASAE, 22:484-493, 1979.

77. Telek, L., “Preparation of Leaf Protein Concentratesin Lowland Humid Tropics, ” in Tropical Foods:Chemistry and Nutrition G. E, Inglett and G. Charal-ambous (eds.], (New York: Academic Press, vol. 2,

78<

79

1979), pp. 659-683.Thring, J. M., “The BOCM-Silcock Green Crop Frac-tionation Process, “ in Green Crop Fractionation, R.J. Wilkins (cd.), British Grassland Society and BritishSociety of Animal Production, Hurley, Miadenhead,England, 1977.Thring, J. M., “Closing of LPC Plant in Britain, ” per-sonal communication, 1982.

80. Vartha, E. W., and Allison, R. M., “Use of Residuefrom LPC Productionin Sheep Feeding,” Proceedingsof the N. Z. Society of Animal Production, 31:64, 1971.

81. Vartha, E. W., Fletcher, L. R., and Allison, R. M., “Useof Residue After Extraction From Lucerne and TamaRyegrass, ” N. Z. Exp. Agric., 1:171-174, 1973.

82. Vosloh, C. J., Jr., Edwards, R. H., Enochian, R. V.,

110 Ž P/ants: The Potentials for Extracting Protein, Medicines, and Other Useful Chemicals—Workshop Proceedings

Kuzmicky, D. D., and Kohler, G. O., “Leaf ProteinConcentrate (Pro-Xan) From Alfalfa: An EconomicEvaluation,” U. S. Department of Agriculture,Economic Research Service, Agr. Econ. Rpt., No. 346,1976.

Selected Readings

Allison, R. M., “Leaf Protein as an Animal and HumanFoodstuff, ” Chemistry and Biochemistry of Herbage,G. W. Butler and R. W. Bailey (eds.], ch, 29, vol. 3 (Lon-don and New York: Academic Press, 1973).

Kohler, G. 0,, Wildman, S. G., Jorgensen, N. A.,Enochian, R. V., and Bray, W. J., “Leaf Protein in Rela-tion to Forage Crop Production and Utilization” in Pro-

tein Sources and Technology: Status and ResearchNeeds, Milner, M,, Scrimshaw, N. S., and Wang, D.I. C. (eds.) (Westport, Corm,: AVI Publishing Co,, 1978),pp. 543-568.

Pirie, N. W., “Proteins,” in Modern Methods of PlantAnalysis, K. Paech and M. V. Tracey (eds.), SpringerVerlag, Berlin, Gottingen-Heidelberg, Germany, vol. 4,1955, pp. 23-68.

Pirie, N. W., “Leaf Proteins, ” Ann. Rev. P1. Physiol. 10:33,1959.

Pirie, N, W., “The Direction of Beneficial NutritionalChanges, ” Ecol. Fd. Nutr. 1:279, 1972.

Pirie, N. W., Leaf Protein and Other Aspects of FodderFractionation (Cambridge, England: CambridgeUni\rersity Press, 1978).

Telek, L., and Graham, D., Leaf Protein Concentrates(Westport, Corm.: AVI Publishing Co., 1983).