Atmospheric oxidation of beta-carotene in aqueous, pentanol, SDS microemulsion systems in the presence and absence of vitamin C

摘要

The atmospheric oxidation of beta-carotene in an anionic surfactant system [aqueous sodium dodecyl sulphate (SDS)] as well as the role that the ascorbic acid plays towards beta-carotene action was studied. beta-Carotene can be solubilized into microemulsions formed by water, pentanol, and SDS. As a symmetrical, nonpolar hydrocarbon it is located in hydrophobic regions of micelles. It is more stable in W/O microemulsions than in the O/W type or in bicontinuous systems. The hydrophobic barrier of SDS association structures in W/O microemulsion can hinder electron transfer from beta-carotene molecules and thereby makes theirs oxidation difficult. Vitamin C addition into the system does not considerably change the antioxidant properties of beta-carotene, which is still a better antioxidant in O/W microemulsion. The presence of beta-carotene influences vitamin C antioxidant action. Vitamin C is more easily oxidized when the concentration of pentanol decreases in the system (in O/W microemulsion). In out, earlier studies, when only vitamin C was present in microemulsion, we had observed a totally different behavior of the system, i.e., an oxidation enhancement with increasing pentanol concentration occurred. It can be concluded that in anionic surfactant systems an antioxidant synergism of beta-carotene and vitamin C exists.