Stability of carotenoids in tomato juice during processing

The stability of carotenoids in tomato juice as affected by various processing treatments was studied. Fresh tomatoes were crushed, hot-broken at 82 °C, screened and the juice was subjected to the following treatments: (1) heated at 90 °C for 5 min prior to canning; (2) heated in water at 100°C for 30 min after canning; (3) heated at 121°C for 40 s before canning (high-temperature-short-time treatment). The results showed that 16 carotenoids, including all-trans plus cis forms of lutein, lycopene and -carotene, were present in tomato juice. Most cis isomers of carotenoids showed inconsistent change during heating. The high-temperature-short-time treatment generated the highest yield of all-trans plus cis forms of lutein and lycopene, followed by heating at 90 °C for 5 min and heating in water at 100 °C for 30 min. Only a minor change in -carotene was observed for these heating treatments.