Optimization of Hydrocolloid Levels in Medium-Chain Triglyceride-Enriched Soymilk by Response Surface Methodology

The application of medium-chain triglycerides (MCT) in food items can pave the way for its increased utilization and for consumers to avail of its benefits. Preliminary studies indicated that soymilk enrichment with MCT requires application of hydrocolloids. This study was conducted to determine the optimum levels of kappa carrageenan (K), locust bean gum (L), and glycerine (G) in MCT-enriched soymilk using response surface methodology (RSM). Addition of 30 mL MCT per 500 mL soymilk formulation was based on consumer acceptance test (n = 51). Range of input variables were 0.025-0.063% (w/v) for K and L, and 1.0-2.0% (v/v) for G. Two-factor interaction (2FI), quadratic, and linear models which predicted the overall acceptability (OA), emulsion stability (ES), and product cost (PC), respectively, were generated: OA = 6.19 – 0.10K – 0.07L – 0.17G + 0.02KL + 0.21KG – 0.33LG; ES = 9.24 + 0.32K + 0.08L – 0.01G + 0.34KL - 0.21KG + 0.61LG - 0.08K² + 0.16L² + 0.16G²; PC = 299.62 + 0.37A + 0.40B + 0.67C. A hydrocolloid combination with 0.025% K, 0.025% L, and 1.0% G was predicted and selected as the “optimal” solution (d_i = 0.903). Model validation using the optimal and two sub-optimal (0.059% and 0.062% K, 0.033% and 0.043% L, and 1.00% G) settings showed that the actual responses of both optimal (7.35 OA, 9.90 mL ES, and Php 292 PC) and sub-optimal solutions (6.80 and 5.98 OA, 10 mL ES, Php 293 PC) were within the 99% (α = 0.01) confidence and prediction intervals of the model.