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Effect of Heat Treatment on Nutritive Value of Soymilk Protein Fed to Weanling Rats
Author(s) -
HACKLER L. R.,
BUREN J. P.,
STEINKRAUS K. H.,
RAWI I.,
HAND D. B.
Publication year - 1965
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.1365-2621.1965.tb01831.x
Subject(s) - chemistry , lysine , weanling , food science , protein quality , protein efficiency ratio , trypsin , trypsin inhibitor , biological value , biochemistry , feed conversion ratio , amino acid , body weight , biology , enzyme , endocrinology
SUMMARY The effect of heating soymilk at 93 and 121°C for varying periods was evaluated in weanling rats. Also determined were trypsin inhibitor retention and available lysine values. Cooking soymilk 1–6 hr at 93 °C had no adverse effect on protein efficiency, growth, or available lysine. With cooking for 32 min at 121°C in contrast, there was a definite decline in protein efficiency ratio, and an indication that available lysine was declining. The drop in available lysine was greater after the soymilk had been heated 40 min at 121°C. The results indicate that the protein efficiency ratio of heat‐processed soymilk is dependent upon both time and temperature of treatment. Also evaluated was the effect of spray‐drying temperature and drying method on the nutritional quality of soymilk. The results indicate that an inlet temperature of 277°C or higher causes a drop in the utilization of soymilk protein, with a concurrent drop in the available lysine. Various methods of drying (spray, vacuum roll, atmospheric roll, and freeze) soymilk did not alter the nutritional quality of the protein to any great extent, although the data obtained for the freeze‐dried soymilk did show a slightly lower growth rate and PER value. Available lysine data obtained for the heat‐processed soymilk appear to be a better indication of protein quality in overheated soymilk than in underheated samples. The percentage of trypsin inhibitor retained, on the other hand, appears to be a good criterion for underheated but not for overheated soymilk samples.