Functional Properties of Sunmul (Soybean Curd Whey) Concentrate by Ultrafiltration

摘要

This study was carried out in order to investigate the feasibility of utilizing concentrated sunmul (soybean curd whey), which is a waste by-product of soybean curd processing, as a functional food ingredient. Sunmul powder was concentrated by ultrafiltration and spray dried with or without dextrin. Oil adsorption capacity of UF retentate powder was similar to that of ISP (Isolated Soy Protein) and higher than that of sunmul powder, whereas water holding capacity of UF retentate powder was lower thanthat of ISP. Protein solubility of all types of UF retentate powder was significantly higher than that of ISP at pH 2.0-10.0 with the lowest protein solubility seen at pH 4.0 and solubility increasing as the conditions became more acidic or alkaline. Emulsifying activity indexes of UF retentate powder at pH 2.0-10.0 were not influenced by pH. Emulsion stability of 4% sunmul solution was lowest at pH 4.0, but that of UF retentate powder was higher at acidic pH values and decreased with increasing pH. Foaming capacities of sunmul and UF retentate powder were high at pH 4.0-6.0, but the foam of UF retentate powder disappeared within 20 minutes in all conditions of pH.