INDUSTRIAL AND ENGINEERING CHEMISTRY
1082
Dutton and Edwards ( 6 ) showed that t h e fat-soluble fluorescing substances arise from the phospholipide fraction of the egg yolk. The facts here presented sholr- that the substances responsible for loss of palatability also oric&iate in the same fraction, and that under the conditions of these experiments the correlation between the Palatability scores and the fat-soluble fluorescence values is very high. Khether the same chemical reaction is responsible for both developments i. still a n open question. The fact that they involve substances of similar naturc vould seem to give greater promise that the t w o reactions f if there are t x o ) may proceed simultaneously and be affected by varying factors in a similar manner. If this is true, fat-solublr fluorescence should prove to be a better index of palatability in whole egg powder? t>hanthe fluorescence developed froin protvin reactions. ACKNOWLEDG31EA-T
Jean Wilbur, Virginia Gcrling, and Katie Sur terfield assisted with the preparatory phases a t various times; E. F. Potter carried out the moisture determinations.
Vol. 38, No. 10
LITERATURE CITED
.Iltlerton, G . . and FeT-old, H. L . , A4rch.Biochem., 8. 415 (1945, dssoc. Official Akgr.Chem., Official and Tentative Methods o [ Arialyais, 5th ed., p. 305 (19403. Bate-Smith, E. C . , Brooks. ,J., and Hawthorne, J. R..J . Roc ('hem. I d . , 62, 97 (1943). Boggs, SI. >I., Dutton. H. J . . Edwards, B. G., and Fevold. H L.. ISD. CXG.CHEM..38, 1052 (1946). Eoggs, 11.SI,,and 1-el-old, H. L., I b i d . , 38, 1075 (1946). Dutton. H . J.. xiid 1.klwarrk B. G . , I b i d . , 38, 347 (1946) I b i d . , ISD. Esb. CHEM.,.Is.\L. ED., 18, 38 (1946). Gane. K.. J . Soc. Chem. I n d . , 62, 185 (1943). Slakower, B., ISD. ESG. C H E x , 37, 101s (1945). Olcott. H . P.. and Dutton, H. J . . I b i d . , 37, 1119 (1945). Pearce. ,J. A , . mid Thistle. 11. W., C a n . J . Research, 20D,278 (1942). Pearce, J . .I.,Thistle, SI. K . , and Reid, >I., I b i d . , 21D,341 (lw3). Stea.nrt, G . F.,Best. Id..and Lowe, B., Proc. Inst. Food Tech. 1943, 77-S9. S t u a r t . L. Y.,Grewr, E JfaQ,,48, 4% (1942'1.
(Dehydrated Egg Powders)
Relation. of Lipide and Salt-Water Fluorescence Values to Palatability MILDRED $1. BOGGS, HERBERT J. DUTTOPU", BEATRICE G. EDWARDS, AXD HARRY L. FEVOLD
To
evaluate the reliability of fluorescence determinations as indices of palatability, fluorescence values for salt water (NaC1) and ether extracts of freshly prepared and stored dehydrated egg powders have been determined and compared with the palatability scores for the same egg powders. Salt-water fluorescence values for stored egg powders were found to correlate well with palatability scores for high moisture (4 to 5%) egg powders, but the correlation was poor for egg powders below 2% moisture. Lipide fluorescence values, on the other hand, correlated
well w-it11 palatability scores for high and low nloisturc powders during storage, and the correlation w-as also better for lipide fluorescence when all classes and grades of egg powders are considered. Because of these facts, and since the lipide-soluble fluorescing substance and the suhstance mainly responsible for loss of palatability both apparently originate in the phospholipide fraction of the egg powders, lipide fluorescence values are believed to he better criteria of palatability than salt-water fluorcsrcnr.r values.
M
present report compares data on palatability, salt-solublc fluort.scence, and lipide fluorescence, obtained from a number of samplc: of dried egg powders t h a t had been submitted to a variety (if processing and storage conditions. The reliability of salt-soluhltfluorescence and lipide fluorescence as indices of palatahility o f these samples is discussed. The egg powders were of t w o kinds-spray-dried po\r-dcrfrom commercial sources and lyophilized powders prepared iii thr laboratory from grade A fresh eggs. The samples studied varic.2 in moisture content and in temperature, time, and gas atmo:plic~ri of storage. For determination of salt-extract fluoresccnw modification of the original procedure of Pierce, Thistle, arid 1 l i . i ~ (10) was used. Egg ponder, after being defatted with chloroforrrl was estrncted in l o r c sodium chloride solution, with 1.igoroii: shaking for 30 minutes at 23" C . The fluorescence of t l w filtered cxtract was determined in a Coleman spectrophotnnietur Kith fluorometric accessories. The conditions of this opwat ion r e r e kept rigidly constant, since it has been found that 111:111> variables affect the results (6, IO). Themethod for detcrminatitrr; of lipide fluorescence is described elsewhere (3),as is alw i t i r method for determination of palatability (1).
EASUREhlEiYT of the fluorescence of salt-water extracts (potassium chloride or sodium chloride) of chloroform-
extracted egg powders has been proposed and used as a method of evaluating objectively the quality of stored dehydrated egg. Values for salt fluorescence were found, in general, t o be inversely proportional t o the quality of the powders as measured by palatability (9). The fluorescent material measured by this test vas shown t o be glucose-protein reaction products (8). A growing appreciation of the fact t h a t salt-water fluorescence by itself IS not a reliable criterion of flavor is evident in the xork of Fryd and Hanson (1). The flavor index proposed by them takes into account moisture, salt fluorescence, glucose content, and free fatty acid. Work in this laboratory points to the phospholipides d s being primarily responsible for the flavor deterioration of dried egg powders during storage (6). Cephalin was also shown to react with aldehydes to give ether-soluble brov-n fluorescent materials (4). This reaction accounts in part for the discoloration and fluorescence in egg lipides during storage of egg powders (9). I t was therefore thought that measurement of fluorescence in the lipide fraction might serve as an indes to flavor change. The 1
Present address, Northern Regional Research Laboratory, Peoria, Ill.
INDUSTRIAL AND ENGINEERING CHEMISTRY
October, 1946
T.\BLE I. SALT-WATER FLCORESCESCE L-hLlZES AND l'ALATABILITY S C O R E S O F S P R b Y - D R I E D EGGPOWDERS ;ample To.
Salt-Sol. Fluorescence
Palatability Score
19 19
8.0 7.7 7.5 7.5 7.0 7.2 6.7 6.5 7.5 8.1 4 4 .. 9 6
1
2
:: 4 5
2
8 1 I Ll
I1 12
1:) 119
20 21 23 24 25
27 28 28
Sample NO.
Salt-Sol. Fluorescence
I'alatahili y Score
29 29 29 29 31 32 33 33 34 31 36 40
5 5 4.9 4.9 4.0 4.9 6.6 6.1 3.8 3.8 3.8
13 14
I5 16 17 18 19 20 21 22 23 24
*
1083
70
2::
TABLE11. S-4LT-lT'ATER F L E O R E ~ C E AS S DCP.
