Studies on the Optical Rotation of Whey Syrup Prepared by Immobilized .BETA.-Galactosidase.

Whey syrup was prepared by immobilized β-galactosidase and its specific rotation was determined. The rate of lactose hydrolysis and the specific rotation of whey syrup increased as the reaction time increased. The specific rotation of whey was +52.41°and that of whey syrup markedly increased and finally reached +78.82°by enzymatic reaction. The increase in specific rotation in the whey syrup indicates that its sweetness increases, and therefore, the whey syrup can be used in such foods as canned fruit, soft drinks, ice cream, and frozen yogurt as a sweetener. There was a positive correlation between the changes in specific rotation and the rate of lactose hydrolysis within a definite reaction time; therefore, a novel method based on the measurement of specific rotation can be used to calculate the rate of lactose hydrolysis and sweetness in the process of whey syrup production. Changes in specific rotation coincided with the changes in galactose content during the reaction; thus, galactose production is the most important factor which determines the changes in specific rotation in the whey syrup.