紫胶涂膜常温贮藏对椪柑挥发性成分的影响

Effect of Shellac Coating Treatment on Volatile Components of Ponkan during the Storage at Room Temperature

研究漂白紫胶涂膜处理对水果常温保鲜贮藏过程中香气成分的影响。用动态顶空密闭循环式吸附捕集法分别采集涂膜椪柑完整果实在贮藏期(涂膜后10～40d)的挥发物,并进行热脱附-气相色谱/质谱(TCT-GC/MS)分析。结果表明,其完整果实挥发物中的香气组分均为萜烯类化合物及其衍生物,主要成分柠檬烯在对照样品挥发物中相对含量始终较低(可能挥发高峰在观测开始之前已出现过),均为(10±3)%,而经6%和12%漂白紫胶涂膜处理后在常温贮藏过程中挥发程度减缓(挥发高峰出现在观测阶段的早期),在挥发物中相对含量分别由10d时的34.67%和40.83%降至40d时的14.64%和11.69%,有利于保持柑橘类水果的特征香气状况;涂膜对挥发物的缓释作用可通过提高漂白紫胶浓度(即相应增加涂层厚度或致密度)加以强化;涂层厚度或致密度均匀性的改善可选择在较高浓度涂膜剂中添加纳米SiOx材料,使缓释效果更加显著(挥发高峰出现在观测阶段的后期),柠檬烯在挥发物中相对含量从10～20d期间均较低(分别为12.41%和10.30%),至30d时才增至19.29%,而至40d时达到35.16%。

In order to investigate the effect of shellac coating treatment on volatile components in fruits stored at room temperature, the volatile components was harvested by dynamic head-space absorption trapping method from the intact fruits of Citrus reticulata Blanco （Ponkan） with shellac coating during the storage period of 10-40 days, and analyzed by thermal cryo-trapping-gas chromatography/mass spectrometry （TCT-GC/MS）. Results indicated that terpenes and their derivatives were the predominantly typical compounds among all volatile samples. Limonene, as the major component, was determined at low content of （10 ± 3）% in the control samples, which was probably due to a pre-experimental releasing peak during the storage period; however, the fruits with treatment of 6% and 12% bleached shellac coating exhibited a decrease in limonene content from 34.67% to 14.64% at the 10th day or from 40.83% to 11.69% at the 40th day. Therefore, shellac coating treatment was beneficial to the maintenance of characteristic aroma in citrus fruits. The slow-releasing effect of aroma components could be strengthened by increasing concentration of coating agent, and the membrane uniform could also be improved by adding auxiliaries such as nano-SiOx. On the other hand, there was a late peak of for the release of limonene, which demonstrated that the content of limonene was increased from 12.41% to 19.29% at the 10th day and from 10.30% to 35.16% at the 40th day.