Lycopene (Z) – isomers enrichment and separation

Summary (All‐E)‐ L ycopene 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.