Degradation of carotenoids in dehydrated pumpkins as affected by different storage conditions

The degradation kinetics of carotenoids in dehydrated pumpkins, stored at 4, 25, and 40 °C under air or controlled atmosphere conditions (N₂), was evaluated using reversed-phase high performance liquid chromatography coupled with diode array and mass spectrometry detectors. The degradations of predominant carotenoids including β-carotene, α-carotene and lutein depended on the storage temperature, the storage duration as well as the presence of oxygen, which was following the first-order kinetics. The temperature dependence of reaction constants were well explained by the Arrhenius relationship. The activation energy (Ea) for carotenoids degradation ranged from 23.69 kJ/mol for lutein in N₂-packaged dehydrated pumpkins to 13.82 kJ/mol for β-carotene in air-packaged samples. Lutein was less degradable than α-carotene and β-carotene in dehydrated pumpkins during storage. Higher all-E-carotenoid degradation in N₂-packaged dehydrated pumpkins stored at 40 °C occurred than that stored at lower temperature under N₂ or air storage, and those storage conditions were beneficial to the formation of Z-isomers (e.g., 15-Z-β-carotene and 13-Z-β-carotene). Storage under N₂ at 4 °C enhanced the retention of all-E-carotenoids in dehydrated pumpkins. Thus, package atmosphere should be paid more attention during long-term storage.