Enriched (Z)-lycopene in tomato extract via co-extraction of tomatoes and foodstuffs containing z-isomerization-accelerating compounds

Abstract

The aim of this study was to promote the Z-isomerization of lycopene in its extraction process from tomato pulp by adding foodstuffs containing Z-isomerization-accelerating com-pounds. The addition of onion, broccoli, mustard, makonbu (Saccharina japonica), or shiitake mushroom (Lentinus edodes) to the ethyl acetate extraction process significantly accelerated the Z-isomer-ization of lycopene. For example, when lycopene was extracted from tomato pulp at 70 °C without foodstuffs, the total Z-isomer ratio of lycopene in the extract was 38.4 ± 0.5%, whereas when onion, broccoli, mustard, makonbu, and shiitake mushroom were added to the process and the extraction was performed using the same procedure, the total Z-isomer ratios significantly increased to 53.6 ± 0.4, 47.9 ± 0.3, 48.2 ± 0.1, 41.5 ± 0.9, and 42.0 ± 1.2%, respectively. Since the above foodstuffs contain large amounts of carotenoid Z-isomerization-accelerating catalysts, i.e., polysulfides, isothiocya-nates, or iodine, those components would promote Z-isomerization of lycopene in the extraction process. Since lycopene Z-isomers potentially have higher bioavailability and biological effects than the all-E-isomer, lycopene extraction with foodstuffs having a Z-isomerization-promoting effect in ethyl acetate should enhance the health benefits of tomato extracts.