Enrichment of Amaranth Oil with Ethyl Palmitate at the sn-2 Position by Chemical and Enzymatic Synthesis

Abstract

Amaranth oil is rich in linoleic, oleic, and palmitic acids. Structured lipids (SLs) with specific functional and nutritional characteristics can be prepared through chemical or enzymatic interesterification. The aim of this study was to increase the palmitic acid content at the sn-2 position in amaranth oil triacylglycerols (TAG) for possible use in infant formula. Chemical and enzymatic interesterification techniques were assessed before selecting the latter for further optimization modeling. Enzymatic interesterification of ethyl palmitate and amaranth oil significantly increased the total content of palmitic acid, reduced linoleic acid content, and increased the amount of palmitic acid at the sn-2 position of the SL product. Even though amaranth oil content of palmitic acid (18.3%) was originally similar to that in breast milk (18.3-25.9%), the structural changes induced through enzymatic modification resulted in a SL closely resembling breast milk fat and hence its possible application as a fat substitute for infant nutrition. A second-order polynomial model was developed to predict the amount of total palmitic acid incorporated when reaction time and substrate level were manipulated, and to optimize the combination of parameters to achieve specific palmitic acid contents in amaranth oil. The resulting model is useful to develop an SL from amaranth oil enriched with palmitic acid specifically at the sn-2 position for possible application in infant formulas.