Use of multi-response modelling to investigate mechanisms of [bêta]-Carotene degradation in dried orange-fleshed sweet potato during storage: From carotenoids to aroma compounds
In order to give insight into ?-carotene degradation mechanism during the storage of dried orange-fleshed sweet potato, and particularly into the role of isomers and norisoprenoids formation, multi-response kinetic modelling was applied. Determination of degradation compounds were carried out by HPLD-DAD and SPME-GC-MS as a function of time between 10 and 40 °C and at four water activities from 0.13 to 0.76. Kinetic modelling was developed assuming first-order reactions and by using mass balance. Eight compounds, namely, two isomers (9-cis- and 13-cis-?-carotene), two ?-carotene epoxides (?-carotene 5,6 and 5,8 epoxide) and four volatile compounds (?-cyclocitral, ?-ionone, 5,6-epoxy-?-ionone and dihydroactinidiolide), were integrated into two theoretical reaction schemes. The different models were discriminated according to goodness of fit to experimental data. This work showed that: (1) the formation of cis-isomers from ?-carotene preceded oxidation, (2) ?-cyclocitral arose directly from ?-carotene scission while the other norisoprenoids resulted from ?-carotene epoxide degradation, (3) cis-isomers were high reactive compounds. Temperature had a major influence on reaction rates k while water activities only impacted k at values under 0.51. Therefore, multi-response modelling is not only a tool to predict ?-carotene degradation but a interesting way to select the appropriate degradation scheme based on the different options presented in literature.