Lycopene (Z) – isomers enrichment and separation


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(All-E)- Lycopene undergoes geometrical isomerisation into (Z)-lycopene isomers with thermal treatment. Influence of three isomerisation methods including ethyl acetate reflux, microwave-assisted reflux and ultrasound/microwave-assisted reflux, and isolation of (all-E)-lycopene from other carotenoids and (Z) lycopene isomers through selective inclusion by deoxycholic acid (3α, 12α dihydroxy-5βcolan-24-oic-acid, DCA) were investigated. The results showed that microwave and ultrasound/microwave-assisted reflux were not significantly different at P < 0.05, but both were significantly different (P < 0.05) over refluxing in ethyl acetate, proportion of (Z)-lycopene isomers reached 54% after refluxing for 5 h. Heterogeneous mixture of isomerised tomato oleoresin containing 54% (Z)-lycopene isomers and 40% (all-E)-lycopene and deoxycholic acid in dichloromethane was incubated at 25 °C for 2 h. Then, the mixture was filtered and from the filtrate 96.6% (Z)-isomers enriched lycopene was obtained. The processes can be used in the production of enriched (Z)-lycopene isomers for food supplements and functional food industry as a natural bioactive ingredient.