Optimization of Volumetric Ratio of Soy Milk and Concentration of Porang Gel on the Properties of Soy Milk Fortified with Ginger Extract

Soy milk is a typical soy protein product and a good source of essential nutrients, however “beany” off-flavor makes soy milk unpleasant or unacceptable to many consumers. The addition of ginger extract in this research is intended to mask the “beany” off-flavor in soy milk. Soy milk is a beverage with an emulsion system that exhibits unstable characteristics during storage. Creaming and sedimentation in protein-rich beverages can be addressed by enhancing system stability using polysaccharides such as glucomannan from the porang plant. Glucomannan has the ability to bind water effectively, restricting molecular movement and thereby improving the stability of soy milk. The objective of this research is to determine the optimal values for volumetric ration of soy milk and concentration of porang gel that yield the desired responses in terms of physical stability, viscosity, and antioxidant activity of soy milk using response surface methodology. The models predicted that the optimal formula was soy milk volumetric ratio of 69.3 (v/v) and porang gel concentration of 1.3%. The verification experiments were conducted in three replications. The results showed that physical stability, viscosity and IC50 value of soy milk were 0.90±0.05, 132.0±5.5 cP and 187.5±35.2 ppm under optimal formulation. The optimization results were validated and found no statistically significant differences at a 5% significance level. Soy milk with good physical stability, viscosity, and antioxidant activity can be prepared with this formulation.