A partially soluble fish hydrolysate product 

 is readily dispersable. It has a higher lipid con- 

 tent but is inexpensive. It is physically stable 

 but has a moderate fish meal odor which may 

 intensify during storage. It has good nutritive 

 value both as a supplement and as a sole source 

 of protein and might be used as a protein sup- 

 plement in cultures or locales where its taste 

 would be acceptable and the caloric value of the 

 lipid desirable. 



Fish protein hydrolysates are probably most 

 suited for use in dry soup mixes, broths, or 

 bouillons. With flavor modifications they might 

 satisfy the need for a soluble protein concentrate 

 to fortify beverages. They could very well be 

 included in savory crackers, sandwich spreads, 

 and pastes. The flavor and nutritive value of 

 certain overly bland processed meats and meat 

 extenders might be improved by inclusion of 

 the fish hydrolysate. 



Whether or not the enzymatically produced 

 FPC is suitable for inclusion in bread has not 

 yet been determined but bread fortified with it 

 would have good nutritional value. Soluble 

 FPC would not be suitable for direct incorpora- 

 tion into pasta products because they would be 

 leached out in cooking. They might, however, 

 be used in sauce formulations for pasta. 



Limited food research has been carried out 

 with the hydrolysate products prepared in the 

 replicate runs. They were incorporated at a 

 level of 10% in plain sugar cookies which were 

 evaluated for flavor, texture, and appearance. 

 Control cookies containing no FPC and cookies 

 containing IPA-extracted hake FPC were in- 

 cluded for comparison. The cookies containing 

 fish hydrolysates were judged to be significantly 

 poorer in flavor. Texture was also diflferent 

 with the hydrolysate-containing cookies being 

 somewhat brittle rather than crumbly. The test 

 cookies were thinner than the controls, but they 

 were not statistically diflferent in appearance. 

 Although the general flavor characteristics of 

 fish protein hydrolysates would be more accept- 

 able in types of food other than cookies, the flavor 

 poses an important problem to be solved. Ad- 

 ditional research is needed on the preparation, 

 processing, and utilization in various foods 

 of biological FPC before they can be consid- 

 ered acceptable for use in most American-type 

 foods. 



STATUS AND FUTURE OF 

 BIOLOGICAL FPC METHODS 



Many diff'erent approaches to the preparation 

 of FPC by biological procedures have been tried 

 by various investigators. A completely satis- 

 factory commercial process having human food 

 applications has not as yet been demonstrated. 

 Fish can be preserved inexpensively in a concen- 

 trated form through biological procedures, but 

 a bland product of the type that may be pre- 

 pared by solvent extraction is difficult if not im- 

 possible to prepare by biological procedures 

 alone. Some proposed processes combine solvent 

 extraction with enzymatic or microbial treat- 

 ment but complete elimination of the use of sol- 

 vents would be desirable and a truly bland prod- 

 uct from such a combination is unlikely. 



A water-soluble FPC is desirable for certain 

 applications and this can be prepared by using 

 proteolytic enzymes. The nutritive value of sol- 

 uble FPC may be limited by inadequate concen- 

 trations of certain essential amino acids unless 

 suitable processing conditions are chosen. We 

 have found that hydrolysis above pH 8.5 with 

 alkaline proteases of Bacillus subtilis gives good 

 yields and amino acid patterns for soluble prod- 

 ucts. The species of fish processed is also a fac- 

 tor in the level of nutritive quality which can be 

 reached. 



The physical, chemical, and organoleptic char- 

 acteristics of enzymatically prepared FPC have 

 not been fully determined and described in this 

 report because additional product development 

 is needed. Organoleptic characteristics, partic- 

 ularly flavor, are the properties of biologically 

 prepared FPC which presently limit their ap- 

 plications. For this reason food research with 

 the products has also been quite limited. 



The first goal of additional research with sol- 

 uble hydrolysates of whole fish should be im- 

 provement of organoleptic and physical char- 

 acteristics while retaining good nutritive value. 

 Additional engineering studies in areas such as 

 centrifugation and mixing power requirements 

 would then be appropriate prior to final scale-up. 



One possible approach to the primary goal of 

 flavor modification is fermentation of enzymatic 

 hydrolysates with suitable microorganisms. 

 Yeast (Jeffreys and Krell, 1965) and carbohy- 

 drate fermenting bacteria (Tada and Nakayama, 

 1956; Krishnaswamy et al., 1965) have been 



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