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Thermal Degradation and Isomerization of β-Carotene in Oil-in-Water Nanoemulsions Supplemented with Natural Antioxidants

Yi, Jiang, Fan, Yuting, Yokoyama, Wallace, Zhang, Yuzhu, Zhao, Liqing
Journal of agricultural and food chemistry 2016 v.64 no.9 pp. 1970-1976
alpha-tocopherol, antioxidant activity, antioxidants, ascorbic acid, beta-carotene, corn oil, emulsifiers, encapsulation, high performance liquid chromatography, isomerization, isomers, medium chain triacylglycerols, nanoemulsions, oxidative stability, sodium caseinate, storage time, thermal degradation
The goal of this study was to see the impact on the retention and isomerization of encapsulated β-carotene (BC) in nanoemulsions fortified with natural antioxidants (α-tocopherol (AT) and l-ascorbic acid (AA)). The physical stability of nanoemulsion, oxidative stability, and isomerization of all-trans-β-carotene (BC) in oil-in-water (O/W) nanoemulsions were determined in the presence or absence of natural antioxidants at 25 and 50 °C at certain intervals of time by high-performance liquid chromatography (HPLC). Sodium caseinate was used as the emulsifier, and corn oil (CO) was more protective than medium-chain triglycerides (MCT) and used for isomerization studies. Mean diameters of control (without antioxidants) and AA- and AT-fortified particles were similar. Mean particle diameter of nanoemulsions increased from 10 to 25 nm at 25 °C and from 40 to 50 nm at 50 °C during 30 days of storage. The isomerization from all-trans-BC to cis-BC isomers was inhibited by antioxidants. The isomerization rates were in the following order: 13-cis-BC > 15-cis-BC > 9-cis-BC. AT had better antioxidant activities than AA in inhibiting BC degradation in O/W nanoemulsions. The results indicated that BC encapsulated in nanoemulsions supplemented with antioxidants could significantly improve BC’s chemical stability.