Identification of Carotenoid Oxidation Products in Pigment Extracts from Star Ruby Grapefruit Pulp at Different Temperatures with Exposure to Light

Pigment extracts obtained from Star Ruby grapefruit pulp were stored at different temperatures (4.5$^{\circ}C$, 23$^{\circ}C$) and exposed to light. many carotenoid oxidation products were formed due to light-exposure during storage periods. They were monitored by using HPLC with photodiode array detection and tentatively identified. Including (all-E)-lycopene and trans-$\beta$-carotene as predominant carotenoids in red grapefruit, 5Z-lycopene, 9Z-lycopene, 13Z-lycopene, and 15-cis-$\beta$-carotene were formed at 4.5$^{\circ}C$, 23$^{\circ}C$. Degradation of all-tarns lycopene was more susceptible to light-exposure and temperature a than that of all-trans $\beta$-carotene. The formation of lycopene cis isomers was favored under lighted condition. Respectively, (5Z)-lycopene was formed in greater amounts than other isomers at 23$^{\circ}C$ storage. The concentration of 15-cis-$\beta$-carotene was significantly increased during storage at 23$^{\circ}C$ storage. The concentration of 15-cis-$\beta$-carotene was significantly increased during storage at 23$^{\circ}C$.