基于GC-IMS和GC-MS分析不同杀菌处理荔枝果汁及其发酵汁挥发性物质的特征

Characterization of Volatile Compounds in Pasteurized Litchi Juice by Different Treatment and Its Fermented Juice Based on GC-IMS and GC-MS

摘要:

采用气相色谱-离子迁移谱（Gas Chromatography-Ion Mobility Spectrometry，GC-IMS）和气相色谱-质谱联用（Gas Chromatography-Mass Spectrometry，GC-MS）分析了热杀菌和超高压前处理对荔枝汁及其乳酸菌发酵汁挥发性物质的影响。结果表明，GC-IMS共检出70种挥发性化合物，以酮类、醇类、酯类、醛类和萜类为主，热杀菌导致新鲜荔枝汁中的丙酸乙酯、2-甲基丙酸甲酯、苯甲醇和1-辛烯-3-醇等成分损失严重，经发酵后其中的丙酸丁酯、三甲基吡嗪、5-壬酮和2,5-二甲基噻吩等成分含量更丰富。而超高压前处理荔枝汁与新鲜荔枝汁组分相似，经发酵后其中的芳樟醇、2,6-二甲基吡嗪、顺式玫瑰醚、苯甲醛等成分含量更丰富；GC-MS共鉴定出51种挥发性化合物，以萜类、醇类为主，热杀菌导致荔枝汁中萜类和醇类含量分别降低了37.05%和31.11%，超高压前处理荔枝汁中萜类和醇类含量则较鲜汁分别增加了33.57%和80.07%，而热杀菌和超高压前处理发酵荔枝汁挥发性化合物总量较发酵前分别增加了46.93%和46.19%，且超高压前处理发酵荔枝汁是热杀菌发酵荔枝汁的2.11倍，更富有愉悦性香气。两种技术相结合，表明了超高压前处理能有效改善荔枝汁及其发酵汁的香气品质，为提升荔枝发酵汁的品质提供了参考价值。

Abstract:

Gas Chromatography-Ion Mobility Spectrometry (GC-IMS) and Gas Chromatography-Mass Spectrometry (GC-MS) techniques were used to analyze the effects of thermal pasteurization (TP) and high hydrostatic pressure (HHP) process on the volatiles of litchi juice and its lactobacillus fermented juice. The results showed that 70 volatiles were identified by GC-IMS, including ketones, alcohols, esters, aldehyde and terpenoids. TP process resulted in a serious loss of ethyl propionate, methyl 2-methylpropanoate, benzyl alcohol and 1-octene-3-alcohol in fresh litchi juice, while volatiles such as butyl propionate, trimethylpyrazine, 5-nonone and 2,5-dimethylthiophene were more abundant after fermentation. The volatiles in HHP pretreated juice were similar to those in fresh litchi juice, and compounds such as linalool, 2,6-dimethylpyrazine, cis rose ether and benzaldehyde were more abundant in its fermented juice; 51 volatiles were identified by GC-MS, mostly including terpenoids and alcohols. TP process caused the contents of terpenoids and alcohols in litchi juice to decrease by 37.05% and 31.11% respectively. Compared with the fresh juice, terpenoids and alcohols contents in HHP litchi juice increased by 33.57% and 80.07% respectively. While the total contents of volatiles in TP and HHP fermented litchi juice increased by 46.93% and 46.19% respectively, compared with the pretreated juice. What’s more, the contents of volatiles in HHP fermented litchi juice were 2.11 times higher than that in the TP fermented juice, with more pleasant aroma. The combination of the two technologies shows that HHP pretreatment can effectively improve the aroma quality of litchi juice and its fermented juice, which provides a reference value for improving the quality of litchi fermented juice.