Atmospheric Oxidation of β‐Carotene in Aqueous, Pentanol, SDS Microemulsion Systems in the Presence and Absence of Vitamin C

Abstract

The atmospheric oxidation of β‐carotene in an anionic surfactant system [aqueous sodium dodecyl sulphate (SDS)] as well as the role that the ascorbic acid plays towards β‐carotene action was studied. β‐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 β‐carotene molecules and thereby makes theirs oxidation difficult. Vitamin C addition into the system does not considerably change the antioxidant properties of β‐carotene, which is still a better antioxidant in O/W microemulsion. The presence of β‐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 our 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 β‐carotene and vitamin C exists.