A Study On Lsolation, Isomerization And Stability Of Tomato Lycopene

A diet rich in carotenoid-containing foods is associated with a number of health benefits. Lycopene is a naturally present carotenoid in many fruits and vegetables. Tomatoes (especially deep-red fresh tomato fruits) and tomato products are considered the most important source of lycopene in many human diets. Epidemiological studies have associated its consumption with numerous health benefits, the effects of which have been attributed primarily to its potent antioxidant properties.Purification and separation of lycopene isomers via Deoxycholic acid (3α,12αdihydroxy-5βcolan-24-oic-acid, DCA) was investigated.Heterogeneous mixture of tomato oleoresin with 6% lycopene content consisting of 97.23% all-trans lycopene and DCA (1:1,2:1,3:1w/w) in dichloromethane was incubated at 25℃for 2h. Lycopene with 96.4% content consisting of 99.69% all-trans lycopene was recovered after washing the (1:1 w/w) mixture with ether, hexane and alkaline solution. Incubation of heterogeneous mixture of thermally isomerized lycopene solution containing 54% all-trans and 41% cis lycopene isomers and DCA,96% all-trans lycopene isomers was recovered after filtering and washing out the DCA.This work demonstrated that, DCA can be used in isolation of all-trans lycopene from other carotenoids and cis lycopene isomers.The degree of isomerization of tomato oleoresin (lycopene content 6%) and purified lycopene (lycopene content 90%), together with their stabilities, were carried out. Geometrical isomerization of lycopene was studied by heating tomato oleoresin in ethyl acetate. An isomerized tomato oleoresin with 50.79±2.13 and 48.03±0.03% content of the cis-isomers could be obtained by refluxing in ethyl acetate for 25 hours. The cis isomers in isomerized tomato oleoresin were shown to decrease to 34.57±0.48% and 26.8±2.44% during storage for two months at room temperature. The results inferred that lycopene in processed product is in dynamic system.The optimum production conditions for improving cis lycopene isomers in tomato products in water (WS) and oil (OS) systems was assessed.The interactive effects of heating temperature (X1),heating time(X2),S:L on cis isomers content was optimized using Response surface methodology with the Box-Behnken design.The optimum conditions for water and oil systems were temperature 120℃, heating time 2.14h and S:L= 1:1(w/w), the percentage of cis isomers content was 51±3.5%and 57±2.6%respectively. The ratio of tomato extract to oil/water had litle influence on the cis lycopene formation. Therefore, from these results it can be concluded that the combination of high temperature and relatively short heating treatment time in oil media could improve cis lycopene isomers or reduce degradation during tomato processing. These research results can be useful in assisting industry to improve processing technology, nutritional value and health-benefits of tomato-based foods.