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To investigate effectors on the colloidal stability of whey and soybean proteins. characteristics of tofu-gel formation, effects of heat treatment and salt composition on the colloidal stability, and effects of heat treatment on storage stability were analyzed. When experimental tofus were made from the mixture of whey and soybean, the calcium in the whey precipitated the soy proteins, and disrupted the gel formation, which resulted in the curd of poor texture. In the heat treatment at 60∼100℃, whey and the whey proteins dialyzed against distilled water were readily preciptated at over 70℃, but the mixture of whey and soy extract as well as sod extract were stable at the range of temperature. The proteins of soy extract, whey dialyzed against sodium phosphate buffer, and the mixture were stable at the same beat treatment, and this suggested that phosphates in the soy extract stabilize specially the whey proteins. Soy proteins were easily destabilized by adding CaCl₂ (0.005∼0.07M) at 80℃ and 70∼85% of the proteins in soy extract and the mixture were preciptated, while only 30∼55% of the proteins in whey dialyzed against distilled water were destabilized at the same conditions. Storage stability at 4℃ of the mixture was increased when the mixture was treated at 63℃ and lower temperature.
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