1990 Volume 37 Issue 10 Pages 751-757
Supernatant of coagulated soymilk on Tofu processing have been termed Yu in Japanese, and have been main waste of Tofu factory. The recovery of protein from the waste Yu water is expected to be effective for reduction of waste treatment facilities and the recovered proteins should be utilized as food materials. The Yu fraction was suggested to contain some factors which effect on growth of rats, since the protein efficiency was negative. Therefore, on the base of preliminary experiment as to solubility of the Yu in water and ethanol, the Yu was fractionated as follows; water insoluble fraction (ISF) from water dispersion of the Yu recovered on Tofu processing, alcohol insoluble fraction (AIF) from the water soluble fraction in 50% ethanol, upper layer (UL) and lower (LL) layer by saturation of the 50% ethanol soluble fraction with ammonium sulfate, and the floating fraction (FF) were obtaind. Main ISF and UL fractions occupied 47.2% of the Yu, and each fraction was devided into nitrogen (ISF, AIF FF and LL) and non nitrogen (UL) groups. Effect of nitrogen fractions on the growth of rats was examined by addition of fractions to the casein diet. As the result, nitrogen balance and organ weights per body weight were as normal, but growth promoting effect was observed in either diet which each fraction was added to. Especially, the highest effect of non protein fraction, LL, in nitrogen fractions was suggested. Furthermore, effect of non nitrogen fraction, UL, on the growth of rats was examined in the same way. As the result, growth promoting effect equal to LL fraction was observed in the case of UL fraction.
