固相微萃取-气相色谱-质谱联用法分析荔枝汁贮藏过程中香气成分的变化

以荔枝果汁为研究对象，研究其在贮藏过程中香气成分的变化，旨在为荔枝汁生产和品质控制提供理论依据。采用SPME/GC-MS法分别对4℃和25℃贮藏的荔枝汁于贮藏4、5、6、7、8周后进行香气成分检测。结果表明：荔枝汁中香气成分总量在4℃和25℃贮藏4周后分别比贮藏前增长39.10%及31.99%。贮藏5周后呈显著下降趋势(P＜0.05)，贮藏8周后香气保留率分别为96.17%及74.49%。其中醇类、酸类香气成分均在贮藏4周时含量最高，此后随着贮藏时间延长含量呈缓慢下降趋势；酯类物质在冷藏6周后达到最高，之后出现显著降低趋势(P＜0.05)；烯类香气成分随着贮藏时间的延长逐渐减少，呈现显著下降趋势(P＜0.05)；醛类香气成分含量在贮藏4周时变化不大，在4℃和25℃贮藏8周后保留率分别为59.86%和55.3%。荔枝汁中几种典型的香气成分如香叶醇、香茅醇、苯乙醇，β-月桂烯，D-柠檬烯，香叶醛的含量也是在贮藏4周达最大，此后逐渐降低。通过对4℃冷藏和25℃常温贮藏的荔枝汁主要香气类型及典型香气成分的比较分析表明，4℃冷藏后香气总量和绝大多数典型香气成分的含量显著高于同期常温贮藏(P＜0.05)。

Changes in Aroma Compounds of Litchi Juice during Storage

The changes in aroma compounds of litchi juice during storage at different temperatures (4 ℃ and 25 ℃) were studied by solid-phase micro-extraction (SPME) coupled to gas chromatography-mass spectroscopy (GC-MS). The results showed the content of total aroma stored at 4 ℃ and 25 ℃ increased by 39.10% and 31.99%, respectively, after 4 weeks of storage. After 8 weeks of storage, the retention rates of total aroma were 96.17% and 74.49% at 4 ℃ and 25 ℃, respectively. The content of alcohols and acids significantly increased (P＜0.01) during the first 4 weeks of storage, and then decreased significantly (P＜0.05) with further storage. The content of esters reached its peak value after 6 weeks of storage and then decreased significantly (P＜0.05) with further storage. The content of alkenes decreased significantly during the whole storage time. The content of aldehydes changed slightly during the first 4 weeks of storage, but the retention rates of aldehydes apparently decreased to 59.86% (4 ℃) and 55.3% (25 ℃) after storage for 8 weeks. The contents of six typical aromas such as citronellol, geraniol, phenylethyl alcohol,β-myrcene, D-limonene, and geranial in litchi juice reached the highest value after 4 weeks of storage, and then decreased with the increase of storage time. As for the retention of total aroma in litchi juice, 4 ℃ was a better storage temperature than 25 ℃.