Hlb Explanation

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The development of microbial lipoxygenaseas an alternative to the enzyme in soy and

bean flour is a further highly interesting topic.Initial approaches failed because of the un-suitable pH optimum of the microbial enzymeand presumably the fact that it is not type II orIII lipoxygenase. Only those are capable of oxidizing lipid-bound fatty acids which sub-sequently bleach lutein, the main carotenoidin the flour (see also chapter 18.3.2, Enzyme-Active Soy Flour).

Polymer-producing enzymes such as alternan

sucrase or dextran sucrase produce hydro-colloids during the fermentation process. Thisresults in increased water absorption anddough stability (Tab. 91) (Popper, 2002).

18.6 Emulsifiers

Due to their polar character, emulsifiers haveinteractions with most ingredients of wheatflour. Fig. 128 summarizes the effects of emulsifiers in baking.

It has been shown that the flour's own polarlipids mainly phospholipids (lecithin) andgalactolipids already have a positive effect onthe volume yield (MacRitchie and Gras, 1973).

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components than standard bread flour (seealso chapter 18.13.2, Rye and High-Fibre

Flour). But their potential for improving thebaking properties of white wheat flour, e.g.dough stability or volume yield, is only limitedand negligible in comparison with other enzymes.

Glucose oxidase is often mentioned and hasalready been described above under oxidation(chapter 18.3.3, page 223). Glucose oxidasewas the hope of many who wanted to omitpotassium bromate or other oxidizing agents.A similar enzyme has recently been launched:

hexose oxidase. The enzyme may be regardedas a glucose oxidase with less specificity, as itnot only oxidizes glucose which is a hexose,i.e. a sugar molecule with 6 (greek: hexa )carbon atoms but also other hexoses suchas galactose which can be found in flour insmaller amounts. So the effect does not differsignificantly from glucose oxidase.

Arabinofuranosidase and sulfhydryl oxidase(Fig. 127) have also been tested for their

possible suitability as flour improvers. So farthey have not found wide distribution becauseof high costs or the lack of obvious benefitsas compared to more common enzymes orascorbic acid.

18.6 Emulsifiers

800

820

840

860

880900

920

940

0 1 2 6 10 100

Dosage (per 100 kg of flour)SOX (mL) Ascorbic acid (g)

V o

l u m e y

i e l d ( m L / 1 0 0 g

f l o u r )

Fig. 127: Steamed bread baking trials with sulfhydryl oxidase (SOX) in comparison with ascorbic acid


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Flour from which all lipids had been extractedonly showed an improvement in volume yieldwhen the polar lipids (or all lipids) were re-added, but not with non-polar lipids (i.e. oil)alone (Fig. 129).

It is probable that all emulsifiers buildcomplexes with gluten, as shown in Fig. 130

for lecithin. On the one hand they increase thebinding forces between the protein chains,but on the other hand they act as a kind of lubricant, improving the gliding of the proteinlayers over each other.

18.6 Emulsifiers

Property Function

Surface activityReduce tension at oil/water interfaceWater absorptionFat dispersion / reduction

Gluten interactionDough elasticityOven springVolume

Starch complexationInclusion in amylose -helixAmylose remains in starch granulateReduce amylopectin aggregation

FreshnessSoftnessAnti-staling

Foam formationGas retentionStructureShape

Fig. 128: Properties of emulsifiers in bread baking

total lipids

non -polar lipids

volume prior to baking

180

200

160

140 B r e a

d v o

l u m e

( m l / 1 0 0 g

f l o u r

0 200 300 400 500 600 700 800 900200 1000

Re-added wheat lipid [mg/100 g flour]

polar lipids

-

180

200

160

140

)

0 200 300 400 500 600 700 800 900200 1000

Re-added wheat lipid [mg/100 g flour]

Fig. 129: Effect of wheat lipids on volume yieldof defatted wheat flour (modif. from MacRitchie and Gras, 1973)

Tab. 91: Effect of alternan and alternan sucrase on the Farinogram

Dosage WA Stability Softening

per 100 kg of flour % min FU

No addition 62.0 9.5 10

100 g Alternan 62.3 9.5 10

300 g Alternan 62.6 8.5 20

500 g Alternan 63.3 8.5 25

1 g Alternan sucrase 62.0 9.5 10

1 g Alternan sucrase, 100 g malt extract 62.2 9.5 15

10 g Alternan sucrase, 100 g malt extract 62.7 10.0 15

100 g Malt extract 61.8 9.5 10

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Some emulsifiers with long non-polar,linear chains, such as monoglycerides, formcomplexes with starch (Fig. 153; chapter18.11), preventing the recrystallization of thegelatinized starch upon storage and thusprolonging shelf-life.

18.6.1 LecithinBakers, especially, have been familiar withlecithin longer than with any other emulsifier.At first it was mainly the effect of lecithin fromegg yolk that was used to distribute largeamounts of fat evenly in the product andachieve a finer crumb and higher bakedvolume, but now concentrated lecithin fromsoybeans is available for this purpose. In itsdeoiled form it is also well suited for use inmills. The most obvious benefit of lecithin isprobably the noticeably reduced stickiness of the dough; bound up with this is bettermachinability, that is also a result of greatersmoothness. The interaction of lecithin withthe starch and its ability to bind water alsoprolong the shelf-life of the crumb. Lecithin

also has a positive effect on volume yield, butin this respect it tends to fall behind syntheticemulsifiers such as diacetyl tartaric esters of mono- and di-glycerides (DATEM). A consumertrend towards slightly lower volume yieldsobserved in some parts of Europe is likelyto increase the use of lecithin again, if theproblem with raw material from geneticallymodified (GM) organisms is finally solved.There are already effective IP 29 systems forsourcing non-GM soybean lecithin. Moreover,lecithin fractions are available that offer theadvantage of being natural emulsifiers withproperties specially adjusted to specificapplications. There is a fraction with a verylow HLB 30 value (hydrophobic) and one witha very high HLB (hydrophilic); this makes onemore suitable for emulsification of water in oiland the other for emulsification of oil in water.

The dosage of lecithin for flour treatment is inthe range of 30 - 150 g to 100 kg of flour. Suchlow doses mainly have the effect of improvingthe processing characteristics of the dough,

18.6 Emulsifiers

hydrophilic

hydrophilic bond

hydrophobic hydrophobic

convalent

Tyrosine

Leucine

Glutamine

Phenyl alaline

Methionine

Threonine Aspartic acid

Valinehydrophobic

hydrophilic

hydrophilic bond

hydrophobic hydrophobic

convalent

Tyrosine

Leucine

Glutamine

Phenyl alaline

Methionine

Threonine Aspartic acid

Valinehydrophobic

Fig. 130: Formation of lipoprotein complexes by emulsifiers

29 IP = Identity Preservation. IP is an active process in which actions are taken to preserve the identity of a higher value product as it moves through the chain to a specific end market. Keeping apart or segregating raw materials is one of theconsequences of applying an IP system. Consumer demand for non-GM or GM free food provides an economic incentive for farmers, processors and distributors to supply such products, which require IP to be accepted by the consumer

(modif. from Codex Alimentarius Commission, 2001). 30 HLB = hydrophilic-lipophilic balance; the theoretical values of HLB range from 1 to approximately 50. The more hydrophilic emulsifiers have HLB values greater than 10, while the more lipophilic emulsifiers have HLB values from 1 to 10. As a general rule, emulsifiers with HLB values in the range of 4 to 6 promote water-in-oil emulsions; values between 8 to18 promote oil-in-water emulsions.


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whereas a considerably larger dose increasesthe stability of the dough, crumb structure,fermentation tolerance, and shelf-life.

18.6.2 Mono- and DiglyceridesMono- and diglycerides are produced bysplitting off a single or two fatty acids fromedible fats and oils. By selecting the fattyacids remaining on the glycerol backbone it ispossible to produce emulsifiers with greatlydiffering properties. For flour treatment thereis mainly a demand for the mono- and digly-cerides with good anti-staling properties.

These are attributed to linear, saturated fattyacids that interact well with starch and thusslow down the staling process. The bestmonoglyceride for this purpose is glycerolmonostearate (GMS). Although GMS andother mono- or diglycerides show their bestfunctionality when hydrated, i.e. as paste,and can therefore only be used in the bakery,they are also suitable for use in milling whenin a fine powder form. The large surface: volumeratio results in fast hydration, and thus

almost the same efficacy.

In other respects, too, these emulsifiers havesimilar effects to lecithin, namely a finercrumb and a greater volume yield. With fat-rich products, especially, the dose requiredmay be up to 1% of the flour.

18.6.3 Emulsifier ComplexesIn many cases it is possible to enhance theproperties of an emulsifier by combining itwith another emulsifier. An example of this isthe mono- and diglycerides, that achieve theiroptimum suitability for use in flour treatmentthrough combination with lecithin. The lecithinimproves their solubility and dispersion, andclearly their interaction with constituents of the flour as well. Well-known and widely usedorganic flour improvers fall into this category.The combination makes it possible to reducethe dose necessary for optimum effect to 100- 300 g with 50% emulsifier in the complex.

Diacetyl tartaric esters of mono- and di-glycerides are also receptive to enhancementwith lecithin: the addition of as little as 10%

lecithin improves their emulsifying effect andalso reduces the vinegar smell.The above combinations are only effectiveif the emulsifiers are mixed before beingconverted into their powdered form.Interestingly, it is not sufficient just to mix theindividual powdered components.

18.6.4 Diacetyl Tartaric Acid Estersof Mono- and Diglycerides (DATEM)

One very effective group of emulsifiers in respectof volume yield is mono- and diglycerides of edible fats esterified with mono- and diacetyl

tartaric acid. DATEM is a heterogeneous mixtureof molecules derived from esterification of acetic acid, tartaric acid and fatty acids(bound to glycerol). Some of the resultingemulsifier molecules are more active thanothers. The structures shown in Fig. 131 werethe most efficient in bread baking trials(Khler, 1999). Both molecules were derivedfrom glycerol monostearate. But most probablythe other molecules do have a co-emulsifyingeffect, which means that the mix is more

effective than a single, purified emulsifier.DATEM is one of the main constituents of most baking improvers, especially when theaim is to produce voluminous baked goodswith a crisp crust. DATEM is not often used inflour treatment; its main application is in breadimprovers utilized in bakeries. The optimum doseis about 300 - 400 g to 100 kg, but for reasons

18.6 Emulsifiers

Fig. 131: Hypothetical structure of the mostbaking-active components of DATEM

O CH

O

R 2

H2C CO R 1

O

C

O

H2C CO

R 3

O

CH CH OH

O

R 3

R = stearoyl residue1R = H or acetyl residue2R = acetyl residue3


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of cost the dosage is often reduced to as littleas 150 g.

18.6.5 Sodium and CalciumStearoyllactylate (SSL and CSL)

These emulsifiers are made from the fattyacid stearic acid esterified with a double esterof lactic acid. The remarks concerning DATEMalso apply to these, but with the differencethat SSL and CSL are especially suitable forbaked goods with a soft crust. Furthermore,they have a better effect on the retention of crumb softness.

18.6.6 Other EmulsifiersTab. 92 summarizes the emulsifiers suggestedfor baking. Sucrose esters seem to be interestingsince they are produced in a wide range of HLB (hydrophilic or lipophilic). The high-HLBvariants, especially, have a good effect onvolume yield and crumb structure at quite lowdosages, but the price is still much higherthan that of conventional baking emulsifiers.

18.7 Acidulants and Acidity Regulators

Sprouting in rye and wheat results in a highlevel of amylase activity in the grain itself withthe usual effects on baking properties. It isgenerally known that even flours with verylow Falling Numbers can produce good bakingresults if well acidified.However, not every bread consumer likes aci-dity and bakeries may also have less and lesstime and personnel available to develop aci-dity by sour dough fermentation. Other ways

are available, and these consist in adding fruitacids, the salts of these and also carbonatesand phosphates approved for use in foods. Itis then possible to adjust the pH of the doughslightly so that it moves out of the range inwhich the enzymes of the grain have theirstrongest effect.

Moreover, these substances influence theswelling of the flour constituents and the pro-

18.7 Acidulants and Acidity Regulators

Tab. 92: Suggested emulsifiers with potential use in baking applicationsEmulsifier Common abbreviation HLB Application and benefit

Acetyl esters of monoglycerides AMG 2.5-3.5 Whipped cakes, volume

Calcium stearoyl lactate CSL 7-9 Bread, shelf-life, volume

Diacetyl tartaric esters of monoglycerides DATEM 9.2 Bread, shelf-life, volume

Ethoxylated mono- and diglycerides EMG 12-13 High-fibre bread; shelf-life(polyglycerates) (combined with monoglycerides)

Glycerol monostearate (non self-emulsifying) GMS 3.7 Shelf-life

Glycerol monostearate (self-emulsifying) GMS 5.5 Shelf-lifeLecithin LC 3-4 Shelf-life, dough properties

Lactyl esters of monoglycerides LMG 3-4 Whipped cakes, volume

Mono- and diglycerides MDG 2.8-3.8 Bread, cakes, cookies, volume

Polyglycerol ester PGE 12-13 Whipped cakes, volume

Propylene glycol monostearate PGMS 1.8 Whipped cakes, co-emulsifier

Polysorbate 60 PS 60 14.4 Whipped cakes, co-emulsifier

Succinyl monoglyceride SMG 5-7 Yeast leavened baked goods; volume

Sorbitane monostearate (e.g. SPAN 60) SMS 4.7-5.9 Whipped cakes, volume

Sodium stearoyl lactate SSL 18-21 Bread, shelf-life, volume

Sucrose esters SUE 7-13 Bread, cake, volume

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Hlb Explanation