Development of goat milk infant formulas by macronutrient modification and their quality evaluation
Maduko, Catherine Obianuju
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Compositional differences between goat and human milk necessitate simulation of goat milk to human milk including the macronutrient compositions such as protein and fat. Macronutrients of goat milk were modified by protein fractionation and lipid modification to make the formulated products homologous to human milk. Goat milk proteins were fractionated in two steps by ultrafiltration process. The effects of heat or frozen treatment, as well as the first-step and second-step fractionations using different membrane sizes were studied. Infant formula analogues were prepared by modifying fatty acid profiles and sterol contents of goat milk with different vegetable oil blends to simulate the fat moieties of human milk for infant feeding. Fatty acid profiles and sterol contents of the formula milks were analyzed. The formula analog composed of 2.5:1.1:0.8 blend of coconut, safflower, and soybean oils had the best similarity to fatty acid profile, total sterol, cholesterol and phytosterol content of human milk. Human milk fat substitutes were produced from vegetable oil blends in a packed-bed bioreactor. The effects of substrate molar ratio, reaction temperature and incubation time on palmitic acid incorporation at the sn-2 position were determined by the response surface methodology. Human milk fat substitutes obtained at optimal conditions of 3 substrate molar oratio (mol vegetable oil/ mol tripalmitin), 14.4h incubation time, and 55C reaction temperature had 40.8% palmitic acid incorporation at the sn-2 position. Structured lipids (SLs) for infant milk formulation were produced by enzymatic interesterification of tripalmitin with vegetable oil blends and fish oil. The SLs were characterized by fatty acid content and structure, melting profiles, oxidative stability index, free fatty acid (FFA) concentration, and tocopherol content. The structured lipids after purification by distillation had melting profiles, oxidative stability index, and initial FFA concentration which were similar to those of the starting oils. The fatty acid composition and structure of the SLs were similar to those of human milk fat. Oxidative stability of the SLs was improved with tocopherol addition as antioxidants and was comparable to that of the vegetable oils and oil blends.