两种干燥方式对香椿粉品质特性的影响

以香椿为原料，研究真空冷冻干燥和喷雾干燥对香椿粉的物理特性、基本成分、抗氧化活性、风味物质和微观结构的影响。结果表明：真空冷冻干燥香椿粉的综合品质较好。在物理特性方面，真空冷冻干燥香椿粉的得率较高、色泽浓绿，复水性、吸油性好；而喷雾干燥香椿粉的溶解度高、堆积密度大。在基本成分方面，真空冷冻干燥香椿粉的蛋白质、皂苷、生物碱含量均高于喷雾干燥；而VC、黄酮、多糖含量在两种干燥方式的香椿粉中无显著性差异。在抗氧化活性方面，真空冷冻干燥香椿粉的DPPH自由基清除力和还原力均高于喷雾干燥。在风味物质方面，从真空冷冻干燥和喷雾干燥的香椿粉中分别鉴定出49和41种挥发性成分，且真空冷冻干燥香椿粉含有较高的特征风味物质2-巯基-3, 4-二甲基-2,3-二氢噻吩。扫描电镜观察微观结构发现真空冷冻干燥香椿粉呈现蜂窝状松散结构，而喷雾干燥香椿粉多呈现出干瘪的圆球体状。综合考虑，真空冷冻干燥是一种适合制备高品质香椿粉的干燥方式。

Effect of Two Drying Methods on Quality Properties of Toona sinensis Powder

The influences of vacuum freeze drying and spray drying on the physical properties, basic components, antioxidant activities, flavor composition and microstructure of Toona sinensis powder were studied. The results indicated that Toona sinensis powder prepared by vacuum freeze drying had better overall quality. Vacuum freeze-dried powder exhibited the higher yield and better greenness, rehydration capacity, oil-absorbing ability; spray-dried powder had better solubility and higher packing density. The contents of protein, saponins and alkaloids in the powder prepared by vacuum freeze drying were significantly higher than those obtained by spray drying; however, the contents of VC, flavonoids and polysaccharide in powder produced by two different drying methods had no significantly difference. The DPPH free radical scavenging activity and reducing power of the powder prepared by vacuum freeze drying were greater than that of spray-dried powder. A total of 49 and 41 volatile components were identifiedin vacuum freeze-dried powder and spray-dried powder, respectively. And vacuum freeze-dried powder retained the higher levels of characteristic aroma components 2-mercapto-3,4-dimethyl-2,3-dihydrothiophene. As for microstructure, vacuum freeze drying presented honeycomb-like and loose structure, while spray-dried powder showed shriveled spherical structure. In summary,vacuum freeze drying was a suitable drying method for the production of high-quality Toona sinensis powder.