Considerable amounts of fish processing byproducts are discarded each year. By developing enzyme technologies for protein recovery and modification, production of a broad spectrum of food ingredients and industrial products may be possible. Hydrolyzed vegetable and milk proteins are widely used food ingredients. There are few hydrolyzed fish protein foods with the exception of East Asian condiments and sauces. This review describes various manufacturing techniques for fish protein hydrolysates using acid, base, endogenous enzymes, and added bacterial or digestive proteases. The chemical and biochemical characteristics of hydrolyzed fish proteins are discussed. In addition, functional properties of fish protein hydrolysates are described, including solubility, water-holding capacity, emulsification, and foam-forming ability. Possible applications of fish protein hydrolysates in food systems are provided, and comparison with other food protein hydrolysates where pertinent.

Fish Protein Hydrolysates: Production, Biochemical, and Functional Properties

Commercially important edible nut seeds were analyzed for chemical composition and moisture sorption. Moisture (1.47-9.51%), protein (7.50-21.56%), lipid (42.88-66.71%), ash (1.16-3.28%), total soluble sugars (0.55-3.96%), tannins (0.01-0.88%), and phytate (0.15-0.35%) contents varied considerably. Regardless of the seed type, lipids were mainly composed of mono- and polyunsaturated fatty acids (>75% of the total lipids). Fatty acid composition analysis indicated that oleic acid (C18:1) was the main constituent of monounsaturated lipids in all seed samples. With the exception of macadamia, linoleic acid (C18:2) was the major polyunsaturated fatty acid. In the case of walnuts, in addition to linoleic acid (59.79%) linolenic acid (C18:3) also significantly contributed toward the total polyunsaturated lipids. Amino acid composition analyses indicated lysine (Brazil nut, cashew nut, hazelnut, pine nut, and walnut), sulfur amino acids methionine and cysteine (almond), tryptophan (macadamia, pecan), and threonine (peanut) to be the first limiting amino acid as compared to human (2-5 year old) amino acid requirements. The amino acid composition of the seeds was characterized by the dominance of hydrophobic (range = 37.16-44.54%) and acidic (27.95-33.17%) amino acids followed by basic (16.16-21.17%) and hydrophilic (8.48-11.74%) amino acids. Trypsin inhibitory activity, hemagglutinating activity, and proteolytic activity were not detected in the nut seed samples analyzed. Sorption isotherms (Aw range = 0.08-0.97) indicated a narrow range for monolayer water content (11-29 mg/g of dry matter). No visible mold growth was evident on any of the samples stored at Aw < 0.53 and 25 degrees C for 6 months.

Chemical composition of selected edible nut seeds

Protein hydrolysates (5, 10, and 15% degrees of hydrolysis) were made from minced salmon muscle treated with one of four alkaline proteases (Alcalase 2.4L, Flavourzyme 1000L, Corolase PN-L, and Corolase 7089) or endogenous digestive proteases. Reaction conditions were controlled at pH 7.5, 40 degrees C, and 7.5% protein content, and enzymes were added on the basis of standardized activity units (Azocoll units). Proteases were heat inactivated, insoluble and unhydrolyzed material was centrifuged out, and soluble protein fractions were recovered and lyophilized. Substrate specificities for the proteases was clearly different. Protein content for the hydrolysates ranged from 71.7 to 88.4%, and lipid content was very low. Nitrogen recovery ranged from 40.6 to 79.9%. The nitrogen solubility index was comparable to that of egg albumin and ranged from 92.4 to 99.7%. Solubility was high over a wide range of pH. The water-holding capacity of fish protein hydrolysates added at 1.5% in a model food system of frozen minced salmon patties was tested. Drip loss was on average lower for the fish protein hydrolysates than for egg albumin and soy protein concentrate, especially for Alcalase hydrolysates. Emulsification capacity for fish protein hydrolysates ranged quite a bit (75-299 mL of oil emulsified per 200 mg of protein), and some were better than soy protein concentrate (180 mL of oil emulsified per 200 mg of protein), but egg albumin had the highest emulsifying capacity (417 mL of oil emulsified per 200 mg of protein). Emulsification stability for fish protein hydrolysates (50-70%) was similar to or lower than those of egg albumin (73%) or soy protein concentrate (68%). Fat absorption was greater for 5 and 10% degrees of hydrolysis fish protein hydrolysates (3.22-5.90 mL of oil/g of protein) than for 15% hydrolysates, and all had greater fat absorption than egg albumin (2. 36 mL of oil/g of protein) or soy protein concentrate (2.90 mL of oil/g of protein).

Biochemical and functional properties of Atlantic salmon (Salmo salar) muscle proteins hydrolyzed with various alkaline proteases.

Meta-analysis of nitrogen balance studies for estimating protein requirements in healthy adults

Functional Properties of the Myofibrillar System and Their Measurements

Hernandez-Lucas, C., Fernandez de Caleya, R., Carbonero, P., Appl. Microbiol. 28, 165-168 (1974). Hernandez-Lucas, C., Fernandez de Caleya, R., Carbonero, P., Garcia-Olmedo, F., Genetics 85, 521-527 (1977a). Hernandez-Lucas, C., Fernandez de Caleya, R., Carbonero, P., Garcia-Olmedo, F., J. Agric. Food Chem. 25,1287-1289 (1977b). Ingversen, J., Hereditas 81, 69-76 (1975). Jones, B. L., Mak, A. S., Cereal Chem. 54, 511-523 (1977). Laemli, U. K., Nature (London) 227,680 (1970). Larkins, B. A., Hurkman, W. J., Plant Physiol. 62,256263 (1978). Mak, A. S., Jones, B. L., J. Sci. Food Agric. 27,205-213 (1976a). Mak, A. S., Jones, B. L., Can. J . Biochem. 54,835-842 (1976b). Miflin, B. J., Shewry, P. R., in “Recent Advances in the Biochemistry of Cereals”, Laidman, D. L., Jones, R. G. W., Ed., Phytochemical Society of Europe Symposia Series, Academic Press London, 1979, pp 239-273. Munck, L., von Wettstein, D., in “Proceedings from Workshop on Genetic Improvement of Seed Proteins”, NAS, Washington, DC, 1974. Nimmo, C. C., Kasarda, D. D., Lew, E. J. L., J. Sci. Food Agric. 25, 607-617 (1974). Nimmo, C. C., O’Sullivan, M. Y., Bernardin, J. E., Cereal Chem.

Chemical composition, nutritive value, and toxicological evaluation of two species of sweet Lupine (Lupinus albus and Lupinus luteus).

This study is concerned with the production of an enzymatic fish protein hydrolyzate (EFPH) from Chilean hake (Merluccius gayi) and its ability to supplement cereal protein-wheat, rice and corn-as tested by biological studies in growing rats. Chemical analyses of several batches showed that the product contains about 63% of protein (N × 6.25). The amino acid profile indicated that all the essential amino acids are present in higher amounts than those established for man in the 1973 FAO/WHO amino acid scoring pattern, with the only exception of threonine which is in slight deficit. Lysine amounted to 11.8% (g per 16g N) of which 75% is biologically available. The biological value of protein of EFPH was tested as protein efficiency ratio (PER) in the rat. The adjusted PER values (casein = 2.50) were consistently higher than or at least equal to the standard. These results point out an excellent biological quality of the protein. Fortification of cereals with EFPH at the levels of 2, 4, 6, 8 and 10% caused an increase in both quantity and quality of dietary protein, the latter being measured as protein efficiency ratio. The results obtained in these experiments show that this type of product can make a significant contribution to populations ingesting low protein diets such as those based on wheat, rice or corn.

Enzymatic fish protein hydrolyzate: chemical composition, nutritive value and use as a supplement to cereal protein

Sensory Evaluation and Acceptability of Cookies Enriched with Sweet Lupine Flour (Lupinus albus cv Multolupa)

Summary

Potato flour (PF) is a material that does not differ significantly from wheat flour (WF) with regards to its physical appearance and chemical composition. For that reason it may be used in bread making. In this study mixtures of wheat flour and potato flour were prepared containing PF at levels of 0, 2, 4, 6, 8 and 10%. The farinograph properties of wheat flour affected by addition of potato flour were studied. Water absorption increased gradually from 62% for WF to 79% for blend with 8% PF. Other parameters such as development time, weakening of dough (Brabender units) and valorimeter value (W) were adversely modified by the addition of potato flour. The bread properties were studied using mixtures containing 0, 2, 4, 6, 8, 10 and 15% PF. The substitution of WF produced increases in water absorption, loaf weight and loaf volume as compared to all-wheat bread. In addition, bread containing PF retained moisture for longer periods than normal bread. Loaves made from wheat flour and 2, 4, 6, 8 and 10% potato flour were tested for their chemical composition and protein efficiency ratio (PER) in the rat. Moisture of bread increased with each increase in the level of potato flour substitution. The protein content of bread showed a progressive fall from 6.8% (at 4% level) to 6.3% (at 10% level). The protein efficiency ratio did not change significantly with the inclusion of potato flour up to 8% compared to all-wheat, but at the 10% level there was a significant reduction in this parameter (P < 0.05).

D. Ballester

Papers

Chemical composition, nutritive value, and toxicological evaluation of two species of sweet Lupine (Lupinus albus and Lupinus luteus).

Enzymatic fish protein hydrolyzate: chemical composition, nutritive value and use as a supplement to cereal protein

Sensory Evaluation and Acceptability of Cookies Enriched with Sweet Lupine Flour (Lupinus albus cv Multolupa)

Potato flour as partial replacement of wheat flour in bread: baking studies and nutritional value of bread containing graded levels of potato flour*

Safety evaluation of sweet lupine (Lupinus albus cv. Multolupa). II. Nine-month feeding and multigeneration study in rats.