INDIVIDUAL CAROTENOID CONTENT OF SRM-1548 TOTAL DIET AND INFLUENCE OF STORAGE-TEMPERATURE, LYOPHILIZATION, AND IRRADIATION ON DIETARY CAROTENOIDS

A modified version of the AOAC procedure for the extraction of carotenoids from mixed feeds was coupled with an isocratic reversed-phase liquid chromatography (LC) method to measure individual carotenoids in SRM 1548 total diet and in a high-carotenoid mixed diet (HCMD). The major carotenoids identified in SRM 1548 were lycopene, beta-carotene, lutein, alpha-carotene, and zeaxanthin in descending order of concentration. The concentration of all carotenoids in SRM 1548 decreased as storage temperature increased. Significant differences in carotenoid concentrations occurred between -80 and 4-degrees-C storage temperatures. Lyophilization of the HCMD significantly decreased beta-carotene and lycopene concentrations and produced an apparent increase in xanthophyll concentrations. Exposure to gamma-irradiation significantly decreased alpha-carotene and beta-carotene concentrations and led to an apparent increase in beta-cryptoxanthin. SRM 1548 was found to be unsuitable for use as a reference material for carotenoid measurements, while HCMD has greater potential as a reference material.