ABSTRACTMost stability studies on carotenoid pigments and vitamins A in food systems concern autoxidation only. Trans‐cis isomerization of all‐trans lycopene (ATL) during tomato processing, and subsequent reversion in storage, lead to different sequence. Proposed reaction pathway scheme, based on known isomer characteristics and constituent reactions, includes lycopene autoxidation/isomerization relationships. The pathway may be applicable more generally to carotenoid degradation in other foods. Stage I: ATL oxidizes or isomerizes (up to 20) to less colored, more oxidizable cis‐forms which either autoxidize or revert to ATL. Processing and storage conditions influence distribution between two routes. Stage II: all forms autoxidize. Oxidized degradation products and fragments accumulate, with product fading and off‐flavor. Presented scheme integrates available information, enables both kinetic and technological system considerations. Knowledge of lycopene behavior aids in improving tomato powder color retention and
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