Use of multi-response modelling to investigate mechanisms of β-carotene degradation in dried orange-fleshed sweet potato during storage: from carotenoids to aroma compounds

In order to give insight into β-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-β-carotene), two β-carotene epoxides (β-carotene 5,6 and 5,8 epoxide) and four volatile compounds (β-cyclocitral, β-ionone, 5,6-epoxy-β-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 β-carotene preceded oxidation, (2) β-cyclocitral arose directly from β-carotene scission while the other norisoprenoids resulted from β-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 β-carotene degradation but a interesting way to select the appropriate degradation scheme based on the different options presented in literature

Insight into β-Carotene thermal degradation in oils with multiresponse modeling

The aim of this study was to gain further insight into b-carotene thermal degradation in oils. Multiresponse modeling was applied to experimental highperformance liquid chromatography–diode array detection (HPLC–DAD) data (trans-, 13-cis-, and 9-cis-b-carotene concentrations) during the heat treatments (120–180 C) of two b-carotene-enriched oils, i.e., palm olein and copra. The test of different reaction schemes showed that b-carotene isomerization reactions were dominant and reversible. The resulting cis isomers and trans-b-carotene simultaneously underwent oxidation and cleavage reactions at the same rate constant. From the kinetic analysis, it appeared that—contrary to oxidation and cleavage reactions—isomerization rate constants did not follow the Arrhenius law. However, the isomerization equilibrium constant increased with temperature, favoring isomer production, particularly 9-cis-b-carotene. Its production was shown to be concomitant with oxidation and cleavage reactions, indicating that 9-cis-b-carotene could be a good degradation indicator during oil storage or processing