Lipase-catalyzed Synthesis of Acyl Ascorbates and Their Application to Foods

摘要

L-Ascorbic acid is a water-soluble vitamin (vitamin C) with high reductivity and is widely used as an additive in foods and cosmetics. Its lipophilic derivative acylated chemically with a fatty acid is also used as an additive in foods rich in lipids. Although 6-O-palmitoyl and stearoyl L-ascorbates are commercially available, they are practically insoluble in water. Ascorbates with shorter acyl chains would be more water-soluble and have more potential as an emulsifier for preparation of oil-in-water (O/W) emulsions. Polyunsaturated fatty acids (PUFAs) are prone to be oxidized. It is expected that addition of ascorbic acid to a PUFA can suppress or retard the oxidation of the PUFA because ascorbic acid is an antioxidant with reductivity. The lipase-catalyzed synthesis of acyl ascorbates in an organic solvent has extensively been investigated. We also reported the synthesis of saturated or unsaturated acyl ascorbates. In this context, we synthesized saturated or unsaturated acyl L-ascorbates through immobilized-lipase-catalyzed condensation of ascorbic acid and a fatty acid in acetone. Antioxidative ability and emulsifier properties of the acyl ascorbates were then examined in this study.