Abstract:Fresh hami jujube fruits were hot-air dried at five different temperatures (35, 40, 45, 50, and 55 ℃) to study the effect of hot-air drying on their epidermal cuticle. The morphology, thickness distribution, and lipid-soluble substances in the cuticle of Hami jujube were studied using scanning electron microscopy (SEM), paraffin sections, and gas chromatography-mass spectrometry (GC-MS). The results showed that restructuring occurred in the epidermal cuticle of jujube during the drying process, becoming more significant with increasing temperature, and that the restructuring process also changed the cuticle thickness. There were changes in the content of lipid-soluble substances in the jujube fruits when dried at different temperatures. At 35 and 40 ℃, the contents of cuticular hydrocarbons, alcohols, and ketones increased, while the contents of acids and aldehydes decreased; at 45, 50 and 55 ℃, the contents of ketones, phenols, aldehydes, and esters increased, while the contents of hydrocarbons and acids decreased. A high drying temperature led to a decrease in the content of medium- and long-chain lipid-soluble substances, and an increase in short-chain lipid-soluble substances. These changes in the contents of lipid-soluble substances might be major factors influencing the changes in cuticular structures.
