Orthogonal experimental design for the optimization of four additives in a model liquid infant formula to improve its thermal stability

In this study, kappa-carrageenan (κ-CGN), a thickener, and soybean lecithin (SBL), citric and fatty acid esters of glycerol (CITREM), and mono-and diglycerides (MDGs) emulsifiers were added to a model liquid infant formula (LIF) to enhance its thermal stability. The dosages of the four additives were obtained by comprehensively analyzing the Turbiscan stability index (TSI), apparent viscosity, and volume mean diameter (D (4,3)). The additives decreased the TSI values from 0.761 to 0.272, increased the apparent viscosity values from 6.875 mPa s to 7.887 mPa s, and decreased the (D (4,3)) values from 1.136 μm to 0.706 μm. The optimal additive levels when added separately were determined as follows: 0.025 g/100 mL κ-CGN, 0.150 g/100 mL SBL, 0.600 g/100 mL CITREM, and 0.100 g/100 mL MDGs. Based on the orthogonal experiment L9 (34), which combined range analysis and analysis of variance, the optimal levels of the four additives when combined were 0.025 g/100 mL κ-CGN, 0.125 g/100 mL SBL, 0.450 g/100 mL CITREM, and 0.100 g/100 mL MDGs. Confirmatory experiments involving milk composition, oxidation stability, and △ backscatter demonstrated that the combined addition of additives is more beneficial to the stability of LIF than the separate addition.