干燥方式对猕猴桃果干品质的影响

本研究以“徐香”猕猴桃为研究对象，分别采用真空干燥、热风干燥、冷冻干燥的方法加工猕猴桃果干，并研究几种干燥方式对其色泽、质构、营养品质及挥发性化合物的影响，旨在选取适宜的猕猴桃干燥方式，为猕猴桃的精深加工提供理论支撑。结果表明：采用冷冻干燥得到的猕猴桃果干能最大限度保持原有的色泽，其a^*值为-7.24，与鲜样最为接近；冷冻干燥猕猴桃果干的硬度、韧性和咀嚼性显著低于其他两组(P<0.05),VC含量为278.56 mg/100 g，总酚含量达1.35 mg/g，均显著高于真空和热风干燥(P<0.05)。因此，冷冻干燥处理能显著降低猕猴桃营养成分的损失。此外，鲜样中共检测出46种挥发性成分，主要挥发性成分为(E)-2-己烯醛和丁酸甲酯。热风干燥的猕猴桃中检测出53种，主要为己酸乙酯和辛酸乙酯；真空干燥果干检测出48种，糠醛和甲基庚烯酮的相对含量较高；冷冻干燥果干检测出40种，丁酸乙酯占比最高。但热风干燥和真空干燥后产生了一些4-甲基-3-戊烯-2-酮、丁酸、正己酸等负面的气味，而冷冻干燥的果干含有更多鲜果中含有的挥发性物质，且干燥后的三组样品中仅在冷冻干燥...

Effects of Drying Methods on the Quality of Dried Kiwifruit

In this study, 'Xuxiang' kiwifruit was used as the research object, and vacuum drying, hot air drying and freeze drying were used to process kiwifruit. The effects of several drying methods on the color, texture, nutritional quality and volatile compounds of kiwifruit were studied to determine the appropriate drying methods for kiwifruit, which would provide theoretical support for the deep processing of kiwifruit. The results showed that the freeze-dried kiwifruit could maintain the original color to the maximum extent, and it's a* value was ?7.24, which was closest to the fresh sample. The firmness, toughness and chewiness of freeze-dried kiwifruit were significantly lower than the other two groups (P<0.05). The V_C content of kiwifruit produced by freeze drying was 278.56 mg/100 g, total phenol content was 1.35 mg/g, which were significantly higher than those produced by vacuum drying and hot air drying. Therefore, freeze-drying treatment could significantly reduce the loss of nutrients in kiwifruit. As for volatile components, 46 volatile components were detected in fresh samples, and the main volatile components were (E)-2-hexenal and methyl butyrate. Fifty-three volatile components were detected in hot air dried kiwifruit, the main volatile components were ethyl caproate and ethyl octanoate. Forty-eight volatile components were detected in vacuum dried kiwifruit, and the relative contents of furfural and 6-methyl-5-heptene-2-one were higher. Forty volatile components were detected in freeze-dried kiwifruit, and the content of ethyl butyrate was the highest. However, some negative odors such as 4-methyl-3-penten-2-one, butyric acid and hexanoic acid were produced after hot air drying and vacuum drying. The kiwifruit produced by freeze drying method contains more volatile substances in fresh samples, and (E)-2-hexenal and methyl butyrate were detected only in freeze drying group. In general, freeze-drying can maintain the flavor of fresh kiwifruit.