Changes in the nutritive value of soy protein concentrate during autoclaving.
Soy protein concentrate (Promosoy R Plus) was mixed with water to form a thick paste and autoclaved at 121 degrees C for 10 min, 30 min, 2 h, or 4 h. Unautoclaved SPC served as a control. Nitrogen solubility measurements and SDS-PAGE analysis indicated that autoclaving resulted in the formation of soy protein aggregates, with a MW of approximately 1 million daltons, held together by non-covalent and disulfide bonds. The 10 min, 30 min, 2 h, and 4 h SPC samples contained 6, 20, 27 and 39% less cysteine, respectively, than the SPC control. No significant differences were found in the PERs, 2.6-2-7, of a casein control, unautoclaved SPC control and 10 min and 30 min autoclaved samples. PERs of the 2 h and 4 h autoclaved samples, 2.0 and 1.9 respectively, were significantly lower than the other four diets. No significant differences were found in the apparent digestibility of the 10 min, 30 min, and 2 h autoclaved samples; the 4 h autoclaved sample however was significantly less digestible. Decreased PERs of autoclaved SPC samples were likely due to (1) crysteine destruction, (2) decreased protein digestibility, and (3) decreased food intake.
Kim
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National Institute on Alcohol Abuse and Alcoholism, National Institute of Health, Rockville, MD.
Barbeau
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D000596:Amino Acids / Q000032:analysis; D000818:Animals; D004063:Digestion; D004591:Electrophoresis, Polyacrylamide Gel; D006358:Hot Temperature / Q000009:adverse effects*; D008297:Male; D009753:Nutritive Value; D014674:Plant Proteins, Dietary / Q000032:analysis / Q000737:chemistry / Q000592:standards*; D051381:Rats; D011919:Rats, Inbred Strains; D012995:Solubility; D030262:Soybean Proteins; D013025:Glycine max
D000596:Amino Acids; D014674:Plant Proteins, Dietary; D030262:Soybean Proteins