Relationship between the kinetics of β-carotene degradation and formation of norisoprenoids in the storage of dried sweet potato chips

The effects of storage temperature (10; 20; 30; 40 °C), water activity (0.13; 0.30; 0.51; 0.76) and oxygen level (0%; 2.5%; 10%; 21%) on the degradation of carotenoids and formation of volatile compounds during storage of dried sweet potato chips were evaluated. A kinetic model was developed for degradation of trans-β-carotene and it showed that breakdown followed first order kinetics with an activation energy of 64.2 kJ mol−1. The difference between experimental data under laboratory or field conditions fitted and data predicted by the model was less than 10% for trans-β-carotene, or for total carotenoids. The formation of the volatile compounds, β-ionone; 5,6-epoxy-β-ionone; dihydroactinidiolide; β-cyclocitral, was measured by SPME-GC-MS and was clearly related to the degradation of trans-β-carotene. It is also suggested that carotenoid degradation in dried sweet potato was by autoxidation because of the trend in β-carotene degradation rate in relation to water activity or oxygen level.