热风干制对哈密大枣表皮角质层的影响

Effect of Hot-air Drying on the Epidermal Cuticle of Hami Jujube

摘要:

为研究热风干制对哈密大枣表皮角质层的影响，本实验在35 ℃~55 ℃供试温度范围内，选用5种不同热风干制温度对新鲜哈密大枣进行干制，利用扫描电镜、石蜡切片对枣果表皮角质层形态、厚度分布进行观察，利用GC-MS对枣果角质层脂溶性物质进行分析。结果表明，干制过程中枣果表面角质层有重构现象，干制温度越高重构迹象越显著，重构过程也引起了角质层厚度的变化。不同温度干制后枣果角质层中的脂溶性化合物有所变化，35和40 ℃条件下角质层中烃类、醇类、酮类含量有所升高，而酸类、醛类含量有所降低；45、50和55 ℃条件角质层中下酮类、酚类、醛类、酯类含量有所增加，而烃类、酸类含量有所减少。干制温度越高角质层中长碳链的脂溶性物质的逐渐减少，而短碳链的脂溶性物质逐渐增加，脂溶性物质的变化可能是角质层结构改变的重要因素。

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.