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AVAILABILITY OF AMINO ACIDS IN SARCOPLASMIC FISH PROTEINS COMPLEXED WITH SODIUM HEXAMETAPHOSPHATE
Author(s) -
PELROY GRETCHEN A.,
SPINELLI JOHN
Publication year - 1971
Publication title -
journal of food science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 150
eISSN - 1750-3841
pISSN - 0022-1147
DOI - 10.1111/j.1365-2621.1971.tb02057.x
Subject(s) - tryptophan , chemistry , pronase , amino acid , lysine , methionine , sodium hexametaphosphate , biochemistry , sodium , threonine , enzyme , food science , chromatography , serine , trypsin , organic chemistry
SUMMARY– Comparisons were made on the availability (enzyme digestion) of 4 amino acids (lysine, methionine, tryptophan, and threonine) in sarcoplasmic fish proteins and sarcoplasmic fish proteins complexed with sodium hexametaphosphate. The protein complexes were formed by reacting 1% solutions of sarcoplasmic fish proteins at pH values ranging from 2–4 and at phosphate concentrations ranging from 0.005–0.05 M. Uncomplexed sarcoplasmic protein was obtained by precipitation from 70% isopropanol. The samples were digested with the enzyme pronase and the available amino acids were measured with a bio‐assay system. No significant differences in the availability (enzyme digestion) of amino acids were found between complexed and noncomplexed samples. Assays of samples dried at 75°C showed that nearly 100% of the methionine, threonine and tryptophan and 85% of the lysine were available. When the samples were subjected to moist heat (50% moisture, 100°C) for up to 24 hr, availability of lysine, methionine, tryptophan and threonine was reduced by 35, 22, 39 and 34%, respectively. Results of this study indicate that the nutritional characteristics of fish proteins are unimpaired when they are complexed with sodium hexametaphosphate.