SsptcrnLwr,t9ts] ~ANE-DRIED MEAT. 111. THE WATER RELATIONS OF AIR-DKIXU, PRE-COOKED BEEF A N D I'OORK 139

Water % .. .. .. .. 0.8 0.8 0.5 6.0 4-15 3.7 3.6 3.4 ml. 0.06rr-NnOEt per g. ether

oxtrnct .. .. .. .. 3.7 3.2 3.3 2.0 2.4' 1.9 1.0 1.8

DISCUSSION Lipase can hydrolyse fats a t temperatures well below the freezing

point: e.g., -30' c., and therefore, since freezing nnd drying both reduce the activity of water in the system, it is not surprising that lipase action occurs in dried egg. A " criticel" water content, below which there is little or no hydrolysis, is also found in other dried mnterinls, e.g., milk nnd meat.

The rote of splitting of glyceride linknges wns several times grenter then that of phosphoric ester linkages (cf. Table V, where the results obtained wit11 powder G at 37Oc. are expressed in terms of 6.-mols.). It is probnble t h n t more than one cnzyine wns active ; botli lipnse and lecithirinse are snid to be present in the yolk of the egg.

TALILE V . Poiiotcdtr G af 37' c. Acid.aolublo I' F.F.A.

(g..ntoms I' (6.-niols. lihrnted . Time liberated per ml. per nil. pulp)

0 0 0 0 1 .n 10

13 3.2 1ii 1U 5.1 28 24 0 - 7 38

(weeks) pulp) x 10* x 10*

1f.lecithin was the ninin source of the liberntcd phosphorus, tlic fact thnt acid-soluble pl~ospl~orus was formed more rapidly t i i n n orthophosplinte* indicates tlint hydrolysis proceeded in n stepwise fashion (phosphocholine or glyeeropliospl~oric acid being possible intermediates). The liberntion of orthophosplinte froiii lecithin would nlso involve the formation of on equivnlent nniount of choline. It is possible, Iiowever, that some phosphorus was derived from other sources ; the estinmtioii of libcrated choline would be of interest in this connerion. ReZatioir of the res i th to observed F.F.A. calucs of contrirercial spray-

dried egg The absolute rates of cheruicnl cliange w c ~ e sninll and it follows

that under normal conditions of preparation and storage there should be no marked increase in F.F.A. or liberated phosphorus. The usunl rnngc of water content of spray-dried egg may be taken as 2-G% and the usual duration and tempernture of storage as less then 24 weeks and 25'6. respectively. With an initinl titre of 1 *4 nil. of 0-05N-sorlium ethoxide per g. of ether extract the order of values to be expected nfter 21 weeks' storage a t 25' C. is given below. Water yo .. .. .. 2 3 4 , 5 (i 7 8 ml. 0.06s-NnOEt p r g. othor

oxtrnct .. .. .. 1.4 1.4 1.4 1.7 2.4 3.0 3-6

Forty-eight conimercinl snmples were analysed and the distribu- tion of tlie values is given below. It should be eniphnsised, however, thnt several of the powders acre selected for examination on the grounds of exceptionnlly poor quality and the distribution is there- fore not a iiornial one. ml. 0.06s-SnOEt per 6. cthcr ulrovo

extract .. .. .. 1-2 2-3 3-4 4-8 fi-I0 10-20 20 h'umbr of sitiiples .. .. 21 12 9 2 5 4 2

Most of the snniples fall within the expected rnnge but sonio of them contniu very lnrge amounts of F.F.A. These high values cannot be explained by a combination of high wnter content and long periods of stornge at high temperatures since the samples

A t tho higher water contentn the rato of liberation of ncid.wlublo phos- phorus wns twico ns y n t na that of ortho hoRphnto (cf. Table IV), i.e.. for eve moleeulu of ort ophosphata formed tEero wns also liberntd ono ntom of 3 0 s horus in aomo other form.

8 Id nnd Tucker, Ind. Eng. Chem. [Anal.], 1938, 80,IIG.

showed none of the chnrncteristic effects of such n treatment (dis- coloration, insolubility, nnd n qnrked burnt odour nnd tnste), and, when received, were of normal wnter content. It therefore seemi probable that the cause was bacterial spoilnge of the pulp before drying.

The work described above was carried out as part of the pro- gramme of tlie Food Inrestigotion Board. I t is published by per- missioa of the Depnrtmeut of Scientific nnd Industrial Resenrch. Low Temperature Stntion for Resenrch in

Biochemistry nncl Biophysics, C;iinbridgc

Ilccriwl June 3, 1948

DRIED MEAT. III. THE WATER RUATIONS OF AIR- DRIED, PRECOOKED BEEF AND PORK

By R. CANE The stntcr contenb of nir-dried ~iw-cookccl lmf'nnd pork vnry with

teniporntum in R norinnl nianncr up to it rclatico Iiuniidity of 0.4, but r i t liiglier liuniiditics tliu water contcnta nro iiplimo"iiiintcly tlio stitno nt the ~IiITcmnt tempcmturrs studied (0-40' c.). Determinations were mode n t relntire liuruidities of 0.10, 0.30,

0.50, 0.70, and 0.80 a t each of tlie teniperntures O', lo', 37" and 60' c. Snmples weighing approxinintcly 2 g. sere allowcd to reach equilibriuni n t the required conditions of temperature and humidity nnd the water contents were tlicn deterniined.

iUatcriul ~tscd.-Tlie inent wns cooked in slabs of size 3 x 14 x 14 in., minced, nnd the conccntriited juice sprayed over tlie mince. It was then dried nt 80' C. (wet bulb GO') until the nient temperature reuclied 65-70' and tlie dry-bulb tenipernturc wus then decrensed to 70". The drying t h e was 44 hours.

Ezjxrii~rctitul corrtZilio,ts.-These were siniilnr to those previoi~sly tlescribed by the author (J.S.C.T., 1941,60, 44).

Deteriiriiintion of i~ioisttcre content.-The moisture content was determined by drying for six hours in nn air oven a t 100" since enrlier erycrimncnts had shown that \dues obtained in this xny agreed well with those obtained by drying to 11 coastnnt weight over phosphorus pentoxide nt 30'. Actually there is a very small increase in tlie npparent water content wlien the samples are dried for 24 hours n t 100' and this suggests that when 11igh.wnter contents are being tletcrniined the most accurate results would be obtained by dryilk for tliis period.

The initinl wnter content of tlic dried beef wns 7-8 g . of wnter per lOOg. of beef (8.4, g. of water per 100 g. of dry weigli~or 14.1, g. per 100g. fat-free dry weight) nnd the fat content 40.2 g. per 100 g. of dry weight.

TAnLE I Ii'aler rrlafioita OJ dried her/ (pre-cookul, air-dried)

1t.K 0' a. 100 0. 370 c. 00' c. g. wnter por 100 g. fnt-frcw dry weight

0.3, 6.0, 4.2, 2.3. 0.30 U.1, 8.9 -0 0.8, 4.3* 0.10

0.80 11.4, 10.8, 10.1, 84, 10.2, 17.0, 11.3, 15.2.

0.80 23.0, 24. -, d 24.8, "1*O0

Usually when the water relations are doternlined a t a nuniber of tenipernturcs it is found that the water content n t any liurnidity increases with fall of tenqwrature, but air-dried pre-cooked beef behaves quite differently. Up to 0.40 relative humidity the water contents vary with temperature in a normal mnnner, but nbovo ibis huinitlity the temperature effect is negligible and tho water contents a t the different temperatures arc npproximntely the same.

Dried pork The initial water content wns 5.2 g. per 100 g: of pork (5.5 g.

water per 100 6. dry weight, or 11.6 g. water per 100 g. fat-free dry weight) and the fat content 52.2 g. per 100 g. dry weight.

0.70

TAIILE 11 H'der rclalionr of dried pork (prc.cwked, air-drird)

R.H. 0" 0. lo"& 3700. 0" c.

0.10 0.30 0.60 0.70 0.80

g. wntcr pcr 0.7, 8.0,

10.8, I7.U, 2'2.5,

100 g. ht-frec dry wciglit ( P I , 3 '3, 8.0, 5.H,

10.2, 8.8, 15.9, 14.2, 93.1, 20. I ,

The Itre-cooked pork sho\vs much the snnie clinrncteristics 11s pre-cooked beef, tlint is nt the higher huniiditics the wntcr conte~its n t n given liuinitlity nntl n t the tliffcrcnt tenipernturcs tenti to nppronch the snnie vnlue.

Esperinieiits nre now in progress in which the writer relntions l it clifferetit. tenipcrntures of raw nntl prc-cooked beef, tlrictl i~ncler siinilnr contlitions, will be conipnred.

The work clescriliecl nbore IWS cnrrictl out 11s pnrt of the ~trogruninic of tlie Food In\&tiptrtion Uonrtl. I t is published 1ty perinissittit of tlic De1tiirtinent ot' Scientific nntl Intlustriril Rcsciireli. The ~i~ens~~rciiieiits.\\~ere cnrrietl out by JIr. 11. .J. Shcpliertl.

Low Teinpcrnture Stntion for Rcsenrch i n I~i~clieniistry nntl Biophysics,

Cnmbridge Ilceelvrd Jiilg 11, 1043

RAPID RING AND BALL SOFIWING-POINT TEST By D. M. WILSON

A niodilietl nietlial of ~~erfomiiiig tho ring nntl Iinll softening-point teat tins h e n inrestigntrtl. Ccrtniii iinprovcnirntR Iinru led to t1ic clrrelopnrnt of n rnpitl inctliotl wliirli grently rcdurew the tiiiir niid Inbour Irquired in ninkinfi n Inrge iiiinihr of roetino control tC8tII.

Hersberger nntl O\*erlkk' Iinre suggested 1111 ingenious niodi- ficntioii of the norniiil ring nntl 1)nIl softening-point test (I.P.-58/42) KO tlint results coultl be olitniiied niorc rnpitlly. Instentl of ririving tlie teinpeniture of the testing Itnth nt H rcgirlnr rnte of incrense i i n d recording the tenipcrnture t i t which the bnll drops 1 in., the tiine is titken for tlie linll to drop the snnie tlistnncc in I I Itnth nt coustnnt, teniperuture. The tcin1ternture is clioscn iiccortling to the npprosininte rnnge witliin which the sninplc is expecteel to soften. Grnplis cnn be drnwii showing the relntioii n t ericli bntli tenipcrnture Itetwecn the tinie required to drop 1 in. nntl the ring nntl I d softeniiig point ns tleterniinctl lty the stiintlnrd inethotl. Once the griiphs litire been ~trepnrctl, tcsts ciin be iiintle rnpitlly.

Tlie publishcd clet.nils were follo\vctl but ninny tliliiculties were experienced in getting sntisfiictory repent results. l<ventuully, while keeping t 3 the principles suggested, ccrtuin niotlificiitions were introduced, nntl tlic nictliotl hus proved to he inost usefitl for rnpitl routine control purposes.

~ I O l l l P I E l l ;\1E:THOI)

Tlic cletuils sliould be followtl csiictly (is tlifl'ereiiccs i n procctlurc n1Fect the ninnner in which the Itnll f i i l lv ; unless it fnlls froin the centre i i n d its lower liiilf reninins encnsccl i n bitunien the results will Itc uurelinble.

(a) fWiq of ri~igs.-Tlic ncw A.S.T.M. slioultlcretl rings slioulcl IJC usctl 11s they provide better sultltort, for Iliirtl i i i icl brittle iniiterinls. Tlie rings sliould IJC \wIl clcnnctl oil their intcrnnl siirfnces to ensure atllicsion of the Itituniinous niutcrinl. Tlicy lire Iicnted nncl plnced on nn niniilgiiniritctl brim plntc. The tiitunii~tous iiinterinl, heiitetl to 160' c. in the cnse of ii bititinen nnd to 130" i n the cnse of pitch wiiiples, is poured in so ns to lenve i i slight escess nbove tlic l e ~ e l of the ring on cooling. The csccss of ninteriiil is cut olF with u s~inrp, sonped knife when it. hiis cooled sufficiently. The cooliiig of soft ninterinls inny Ite linstcncd Ity iinniersing the fillet1 rings in cold wnter.

( I ) ) I'esfiny for .sojtcniq poinf,-Tlie nplirosininte softening-point rnngc of the nintcriul cnn be ,cstinintcd, nfter II little experience, by

I'roe. Amor. Bar. Teat llnt., llU2, I'roprint 78.

prcssurc wit.11 the thumb nnil and tlie npproprinte trentincnt adopted nccorclingly. Iinniedintely nfter levelling off the surfnce the snmplc is plnced in n nntcr-lintli n t either 15' or 25' c., nccording to the softening-point rnnge, for exnct.ly 5 niinutes. It is then trnnsferred to tlie testing bath nt one of the tenipcrntures ,shown in the table, ii biill being plncetl on the surfnce of the bitunien as the sninltle is lo\veretl into tlie 1int.h. The tinie is'tnkeii from the moment the snniple enters the Imth for the boll to drop 1 in. Cnlihrntion gruphH nre tlrnwi to show the relntion Itetween the softening point tleter- iiiinetl lty tlic atniitlnrtl niethotl nntl the time in seconds required for the one-inch fiill for i t nuniltcr of different snniplcs. From these griiphs, the time being known, t,lie softening point cnn be rend otT for ril l subscqiicnt sninples.

(c) &tlr tciiri'erntrcres.-Tlie nIiproprin te testiug lint11 tenipeniturw iire :

Softening-point I'reliininnry , Testing rniige of bntli Iintli

rnnqilr, 'c. tcln]'. tenqi. 350 3rk-46"

50-UBO 550 { 400 3H-500 } 150

I l T i H B O } 260 { gB0 . i T i ! I V

((1) Apix~rrt~it,s.-Tlie genernl nrrnngenieiit of the uppiirntus is Tlie testing bnths m e niounted on well ltrncketri v1101vn in Fig. 1.

FlO. I

t Eiieryy regulator

forliuiiirrmlon hcnlrr

nntl the liench below curries the riirious control switclies. The tenipernture of the 15' bntli is ndjusted Ity udniitting cold wnter froni the ninins, lifter siphoning out excess of writer. In hot weuther it is necessnry to use ice. The teinperiiture of the other h t h s is coiitrollctl nutoinnticnlly by nienns of hot-wire vncuuin switches, either in conjunction with filed contnct tlierinonicters (for tlie 25" Iintli) or by ndjustnble contnct tliernioineters €or the testing Lnths. The telnperclturc in encli testitig IiritJl is kept itriiforni hy n suitnltly clriveu prolicller wliicli slioulcl be titopped during the finnl stnges of tlie test iii order to avoid clisturbnnce to tlie 1~1111 us it fnlls. Tlic biitlis nre licutctl clcetricnlly by iinnicrsion Iicnters. The life of thv cont r d tlicrnio~netcrs would be prolonged if tlieriuionic vnlves were iitied in conjunction with the \wuuni switches ns the nniount ol' current pnstiing tlie contnct points coultl tlien be reduceti. JOOO-C.C. ltenkers nrc used for the testing bnths. The cnrriurs cun be of the conrentiontrl type and cnu be ninde to hold four or niorc ring^. A bull guide tihould be fitted so thut the l~nlls cun be centred HCCU-