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 degreesC, screening, heating at 121 degreesC for 40 s and then storing in the dark or under light at 4, 25 and 35 degreesC 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 beta-carotene and lycopene. However, light exposure promoted the formation of di-cis-, 9-cis- and 13-cis-beta-carotene. For lycopene, 15-cis-lycopene was the major isomer formed during dark storage at 4 degreesC, while 9-cis- and 13-cis-lycopene were favoured at 25 degreesC and 5-cis- as well as 13-cis-lycopene dominated at 35 degreesC. Under light storage, both 9-cis- and di-cis-lycopene (II) were the main isomers generated at 35 degreesC, whereas 13-cis- and 15-cis-lycopene were the most abundant at 4 and 25 degreesC. (C) 2004 Elsevier Ltd. All rights reserved.