97.

98.

99.

I teneur en se\ de la chair saumuree; (5) faire l' /valuation sen­a 'e\le de cette chair saumuree aupres de 30 consommateurs. Les

son I 'd d h d' d····e Itats demontrerent que e pO! s u omar CUlt et rame etaltr ~ron 90010 du poids vivant. La chair trempee dans 0010 NaClenntenait environ 0.3010 de NaCl et cette valeur augmentaitco . I If" draduellement jusqu'a 1.9010 orsque e saumurage se alsalt ansfoOJo NaCI. 11 fallait 1O~0 de Nacl dans la solution de ~rem~agepour qu'il y ait un gam Important de rendement en chair. Memea 10010 de saumurage, les consommateurs ne trouverent pas la chairtrop salee. 11 y aurait des avantages asaumurer apres cuisson.

A STUDY OF THE GASTRIC PROTEINASES OF THE AT­LANTIC LOBSTER (Homarus americanus). F.M. Bartlett*, T.A.Gill, S. MacLean and K. Wong, Canadian Institute of FisheriesTechnology, Technical University of Nova Scotia, Halifax, N.S.B3J 2X4.

Spoilage of lobsters is primarily proteolytic in nature with theproduction of volatile base nitrogen. Autolytic enzymes are majorcontributors to the degradation of both raw and cooked lobstermuscle protein. Recent reports of heat-stable proteinases in thegastric juice of the Atlantic lobster prompted this investigation intothe possible contribution of such enzymes in the spoilage oflobster. In addition, the potential value of these proteinases asindicators of adequate cook-times during the heat processing oflobsters was assessed. Three proteinases of the gastric juice of livelobsters were separated by gel filtration using fast protein liquidchromatography (FPLC) and characterized with respect to pH andtemperature optima, heat stability, and substrate specificity. Eachwas found to be an acid cysteine proteinase capable of hydrolyzinga variety of proteins including solubilized lobster muscle. Thekinetics of the thermal destruction of the proteinases was alsodetermined from which reconmendations for the optim cook-timefor whole lobsters at 100 C are based.

CONSERVATlON DES PIGMENTS CAROTENOIDES DANSDES ENSILAGES DE RESIDUS DE POISSON ET DE CRE­VETTE AVEC UN ANTIOXIDANT. P. Bryl* et A. Gendron,Direction de la recherche scientifique et technique, Ministere deI'agriculture, des pecheries et de I'alimentation, C.P. 1070, Gaspe,P.Q. GOC IRO.

Nous avons evalue la possibilite de conserver les pigmentscarotenoides avec du BHT dans des ensilages acides a base deresidus de crevette et de poisson. Deux melanges constitues de 50010de residus de crevette et 50010 de residus de plie (melanges I et 2)et deux autres avec 50010 de residus de crevette et 50010 de residusde sebaste (melanges 3 et 4) ont ete etudies. lis contenaient del'acide formique et de l'acide sulfurique, le pH etait d'environ 3,5et 200 mg/kg de BHT ont ete ajoutes aux melanges I et 3. Nousavons constate que les carotenoides se degradaient rapidementdans les ensilages sans antioxydant mais qu'ils pouvaient etreconserves avec le BHT.

PRODUCTION AND PROPERTIES OF ESTERASE FROMLactobacillus casei·subsp.-casei S93. S.Y. Lee, B.H. Lee andK.A.A/Rahim, Department of Food Science and AgriculturalChemistry, Macdonald College of McGiIl University, Ste. Anne deBellevue, P.Q. H9X ICO.

Esterases/lipases from lactic acid bacteria are known for theirfunction in the production of enzymc-modified cheese and flavorenhancement during the maturation of cheese. However, theproperties and the kinetic behaviour of these enzymes have notbeen well studied. Lactobacilluscasei-subsp.-casei 593 was selectedamong 20 different strains using the APIZYM (microenzyme)technique and chromogenic substrates. This paper will focus onthe purifiation and characterization of the esterase/lipase using theFPLC system and "Phast" system.

Can. Inst. Food Sci. Technol. J. Vol. 22, No. 4. 1989

lOO. PRODUCTION AND PROPERTIES OF LACTASE FROMPSYCHROTROPHIC Bacillus SPECIES. K.A.A/Rahim, B.H.Lee and S.Y. Lee, Department of Food Science and AgriculturalChemistry, Macdonald College of McGiIl University, Ste. Anne deBellevue, P.Q. H9X ICO.

Lactose intolerance, lactose crystallization, and the disposal ofcheese whey are serious problems associated with the milk sugar.Lactases or beta-galactosidases are industrially important enzymesto solve these various problems. Commercial lactases are fromyeasts (K.Lactis) and fungi (Asp. niger), but they are still expensiveand has low active at low temperatures. However, the psychro­trophic microorganisms were not tried for the enzyme production.Several Bacillus strains were examined for producing lactase at lowtemperatures. Cell lysis techniques such as French press were usedfor extracting the enzyme which showed high activity at lowtemperatures. This paper describes the purification, charac­terization, and the kinetic studies of this enzyme and its applica­tions in selected dairy products.

101. IMPROVED ESTIMATION OF MILK SOLlDS-NOT·FAT BYINFRARED ANALYSIS. M.J. Makarchuk* and A.R. Hill,Department of Food Science, University of Guelph, GUe\ph, Ont.NIG 2WI.

Two approaches were used to improve the precision and ac­curacy of instrumental (Multispec M milk analyzer) estimation ofmilk solids-not-fat at the Ontario Central Milk Testing Labora­tory. (I) In a comparison of primary standards the AOAC methodgave lower total solids values (mean difference = 0.033) and betterrepeatability than the CEM AVC 80 microwave moisture. (2)Alternative calibration procedures were tested. Intercept basedregression gave a more precise estimate than a zero based regres­sion. Frequency of calibration and alternative weightings for fatsignals A and B had no significant effects on instrumental totalsolids estimation.

102. PREPARATION AND CHARACTERIZATION OF ENZYMICMILK PROTEIN HYDROLYSATES FROM AN ULTRA­FILTRATION REACTOR. C. Bard* and S. Gauthier, Groupe derecherche STELA, Departement de sciences et technologie desaliments, Universite Laval, Quebec, P.Q. GIK 7P4.

Skim milk powder (33.6OJo protein) and sodium caseinate (85.6OJoprotein) were hydrolysed with trypsin and chymotrypsin in (E/S:0.5010) in an ultrafiltration membrane reactor (PM30). Chymotryp­tic hydrolysis produced more small peptides than tryptic hydro­lysis. These hydrolysates were further separated by ultrafiltration(PMI) to obtain fractions of different compositions and molecularweight distribution profiles. With skim milk powder, the secondultrafiltration increased the protein content (27OJo vs 47010) anddecreased lactose (66OJo vs 43010). Furthermore, it contributes tothe enrichment of retentates in large peptides, as it is shown byhigh performance size exclusion chromatography. These results arediscussed in terms of possible applications for uses in the foodindustry.

103. A STUDY OF THE MICROBIOLOGICAL QUALITY OFGOAT MILK IN QUEBEC. P.Tirard-Collett, J.A. Zee*, L. Car­michael and R.E. Simard, Departement de Nutrition humaine etde Consommation, Universite Laval, Quebec, P.Q. GIK 7P4.

The microbiological quality of goat milk collected in Queebecfarms was observed during a one-year period. Microbial countsincreased during the summer period. Only one farm had 105c.f.u.per ml in 50010 of samples taken from storage tanks. Coliformswere 103 even when total c.f.u. was 106

. No relationship betweensomatic cell counts and bacterial counts was found. Exponentialbacterial growth began after a lag of at least 3 days at 0-4°C. Goodhygiene, rapid cooling and refrigeration as well as frequent collec­tion by refrigerated vehicles ensure the production of good qualitymilk.

Abstract / 415