Cis (Z)-lycopene exhibits higher bioavailability and tissue accumulation efficiency compared with all-trans (E)-lycopene. A simulated food system was developed to convert all-E-lycopene to its Z-isomers during processing. This system consisted of an aqueous phase containing plant-derived sulfur-containing compounds and a medium-chain triglyceride (MCT) oil phase with dissolved all-E-lycopene. The study aimed to evaluate the effects of sulfur-containing compounds from different plant sources and heat treatments on lycopene isomerization and degradation. The results indicated that, compared with shiitake extract, leek extract, glucoraphanin, wasabi extract, and horseradish, allicin, alliin, and sulforaphane significantly promoted the Z-lycopene content under the optimal heat treatment conditions. The Z-lycopene content increased from 4.91 % to 77.1 %, 68.91 %, and 75.84 % in the allicin, alliin, and sulforaphane groups, respectively. Additionally, except for the shiitake extract group, the addition of other sulfur-containing compounds did not significantly affect lycopene degradation compared with thermal treatment alone (p > 0.05). For better quantitative analysis in food systems, alliin was used as a reference. The application of this method demonstrated that in screened alliin-rich garlic juice (21.20 mg/g) mixed with tomato pulp and MCT oil system, the percentage of total-Z-lycopene increased from 12.14 % to 59.57 %. The bioaccessibility of total-Z-lycopene significantly improved with the addition of garlic juice (p < 0.01). Among all isomers, the bioaccessibility of 9-Z-lycopene and 5-Z-lycopene showed the most significant increase (p < 0.01). This novel tomato pulp system enables the effective utilization of lycopene during processing.
Keywords: Allicin; Alliin; Bioaccessibility; Garlic juice; Isomerization.
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