Isomerisation and degradation of lycopene during heat processing in simulated food system

The degradation and/or isomerisation of lycopene have an important influence on its bioavailability and bioactivities. Existing studies have shown that the configuration profiles and stability of lycopene will be changed because of heat processing, but the relationship between the structure conversion of lycopene and the intensity of heat treatment is yet to be further studied. To simplify the experiments, Lycopene-Octyl/Decyl Glycerate-TBHQ system was established to simulate real food system, C30-HPLC system was used to determine the amount of different lycopene isomers, from which total lycopene, the percentage of Z-isomers to total lycopene before and after heat processing can be calculated to describe the isomerisation and degradation of lycopene during heat processing. The results showed that the degradation of lycopene in the simulation system follows a first-order kinetic model and the degradation rate constants were 2.4×10-3, 4.3×10-3, 1.52×10-2 and 3.32×10-2 min-1 at 100, 115, 130 and 145oC respectively. The apparent activation energy was 77.24 kJ / mol. The contents of total lycopene, all-E lycopene and its Z-isomers followed fairly good regularity during the processing.