Synthesis and Characterization of a Structured Lipid from Amaranth Oil as a Partial Fat Substitute in Milk-Based Infant Formula

The aim of this study was to use enzymatic interesterification techniques to modify underutilized amaranth oil as a structured lipid (SL) by increasing its palmitic acid content at the sn-2 position and incorporating docosahexaenoic acid (DHA). This SL can be partially or complementarily used in milk-based infant formulas to deliver a lipid component similar to that in breast milk. Amaranth oil was modified by enzymatic interesterification in two stages. First, the palmitic acid content was increased specifically at the sn-2 position to resemble breast milk triacylglycerols (TAGs) using Novozym 435 lipase. Then DHA was incorporated, mainly at the sn-1,3 positions using Lipozyme RM IM, a sn-1,3 specific lipase. An optimization model was developed to determine the exact parameter combinations to incorporate a specific amount of DHA (1.0-2.5%). The model suggestions were used for a gram-scale interesterification to yield the expected product. The final SL composition was as follows: palmitic acid, 33.9%; stearic acid, 2.8%; oleic acid, 23.3%; linoleic acid, 37.3%; linolenic acid, 0.7%; and docosahexaenoic acid, 1.9%. The original amaranth oil and the final SL were characterized by determining the fatty acid composition, melting profile, chemical characteristics, oxidative stability (peroxide, p-anisidine, and total oxidation values), and phytosterol, tocopherol, and squalene contents. The physical and chemical characteristics determined in this study support the potential application of DHA-containing customized amaranth oil (DCAO) as a partial fat substitute or complement for milk-based infant formula. Research on the application and stability of this SL used in an infant formula is being conducted.