气相色谱—离子迁移谱技术分析干燥方式对柠檬片挥发性物质的影响

目的：为柠檬片干制过程的风味品质调控提供参考依据。方法：采用气相色谱—离子迁移谱(GC-IMS)技术，结合主成分分析(PCA)，探究冷冻干燥(FD)、热风干燥(AD)、红外干燥(IRD)及真空干燥(VD)对柠檬片挥发性物质含量的影响。结果：鲜柠檬与FD处理、AD处理、IRD处理、VD处理的柠檬片中均检出了72种挥发性物质，在各处理的柠檬片中含量不同，对柠檬片风味产生了影响，包括20种萜烯类物质、16种酯类物质、13种醛类物质、13种醇类物质、7种酮类物质、2种酸类物质和1种呋喃类物质。与鲜柠檬相比，4种干燥方式处理后，柠檬片中标志挥发性醇类和酯类物质含量下降，醛类物质含量上升，而萜烯类物质含量较为稳定。指纹谱图结果表明IRD和AD处理的柠檬片对于丁酸乙酯、乙酸甲酯保留效果较好，糠醛和己醛含量有所上升，PCA结果表明鲜柠檬片与干制样品具有明显差异，热图聚类表明IRD与AD、VD处理效果较为相似。结论：相比其他干燥方式，IRD处理对柠檬片的标志性酯类物质的保留效果更佳，高于其他处理组11%~27%，同时标志挥发性醛类物质含量增加较多，与鲜柠檬相比增加了53%，对其风味具有积极影响。

Effects of dehydration methods on the volatile components of lemon slices with GC-IMS

Objective:In order to investigate the effects of freeze drying (FD), air drying (AD), infrared drying (IRD) and vacuum drying (VD) on volatile components content of lemon slices.Methods:Gas chromatography-ion mobility spectroscopy (GC-IMS) was used in this study, and the principal components analysis was performed to analyze the volatile components of lemon slices exposed to different drying methods.Results:72 kinds of volatile components were detected in fresh lemon slices treated with FD, AD, IRD and VD, and their contents were different in the slices treated with FD, AD, IRD and VD, which influenced the flavor of lemon slices., including 20 terpenes, 16 esters, 13 aldehydes, 13 alcohols, 7 ketones, 2 acids and 1 furan. Comparing with fresh lemon (Control), and treating with 4 kinds of drying methods, the contents of volatile alcohols and esters decreased, the contents of aldehydes increased, while the contents of terpenes remained stable. The results of fingerprint spectra showed that IRD and AD treatments had better retention effect on ethyl butyrate and methyl acetate, and the contents of furfural and hexal increased. PCA results showed that fresh lemon slices were significantly different from dry lemon slices, and heat map clustering showed that IRD treatment was similar to AD and VD treatment.Conclusion:Compared with other drying methods, IRD treatment had a better retention effect on the ester volatile components of lemon slices, which is 11%~27% higher than other treatments. Meanwhile, the content of marker volatile aldehydes increased more, which is 53% higher than that of fresh lemon, which has a positive effect on the flavor of lemon slices. This study will provide a reference for flavor quality control of lemon slices during drying process.