Carotenoid stability during production and storage of tomato juice made from tomatoes with diverse pigment profiles measured by infrared spectroscopy.

Chemical changes in carotenoids and lipids were studied during production and storage of canned tomato juice using ATR infrared spectroscopy and HPLC. Samples from 10 groups of tomatoes with different carotenoid profiles were analyzed fresh, after hot-break and screening, after canning, and at five different time points during 1 year of storage. An apparent increase of carotenoids was observed after hot-break due to improved extraction efficiency. This increase was accompanied by some degree of lipid oxidation and carotenoid isomerization. Canning produced the most intense changes in the lipid profile with breakdown of triglycerides ( approximately 1743 cm(-1)), formation of fatty acids ( approximately 1712 cm(-1)), and degradation and isomerization of trans-carotenoids ( approximately 960 and approximately 3006 cm(-1)). Isomerization was corroborated by the relative increase of HPLC areas corresponding to carotenoid cis isomers. Canning reduced trans-lycopene, trans-delta-carotene, trans-beta-carotene, and trans-lutein by 30, 34, 43, and 67%, respectively. HPLC data indicate that canning causes a drastic reduction of tetra-cis-lycopene and promotes its isomerization to other geometric forms, including all-trans-lycopene. Infrared spectra of tomato juice lipid fractions correlated well with the number of days in storage (SECV < 11 days, r values > 0.99), demonstrating continuous degradation of lipids. Results demonstrated that individual carotenoids and their isomeric forms behave differently during production and storage of canned tomato juice. Information collected by infrared spectroscopy complemented well that of HPLC, providing marker bands to further the understanding of chemical changes taking place during processing and storage of tomato juice.