Stability of carotenoids in tomato juice during storage

The stability of carotenoids in tomato juice during storage was studied. Tomato juice was processed by hot-breaking of tomatoes at 82 °C, screening, heating at 121 °C for 40 s and then storing in the dark or under light at 4, 25 and 35 °C for 12 weeks. Results showed that the amounts of all-trans-lutein and its cis isomers decreased with increasing storage time for all the treatments. Light enhanced the degradation and isomerization of all-trans-lutein, and 13-cis-lutein was more susceptible to formation than 9-cis-lutein. Similar trends were observed for β-carotene and lycopene. However, light exposure promoted the formation of di-cis-, 9-cis- and 13-cis-β-carotene. For lycopene, 15-cis-lycopene was the major isomer formed during dark storage at 4 °C, while 9-cis- and 13-cis-lycopene were favoured at 25 °C and 5-cis- as well as 13-cis-lycopene dominated at 35 °C. Under light storage, both 9-cis- and di-cis-lycopene (II) were the main isomers generated at 35 °C, whereas 13-cis- and 15-cis-lycopene were the most abundant at 4 and 25 °C.