两种乳杆菌发酵西瓜汁挥发性风味物质的研究

Study on the Volatile Flavor Compounds of Watermelon Juice Fermented by Two Lactobacillus Species

摘要:

本文研究了嗜酸乳杆菌（LA）和植物乳杆菌（LP）发酵西瓜汁（以黑美人西瓜为例）挥发性风味物质,并与西瓜原汁挥发性风味物质进行了比较分析。通过采用静态-顶空固相微萃取（HS-SPME）的方法，利用气质联用仪（GC-MS）来测定分析西瓜原汁、发酵10 h、24 h、48 h西瓜汁的挥发性风味物质变化。实验研究共分离鉴定出124种挥发性风味物质，其中醇类29种，醛类19种，酮类13种，酸类22种，烃类11种，酯类17种，其他类13种。无论是西瓜原汁还是发酵汁，醇类物质都是主要的挥发性风味物质，在原汁中相对含量高达51%。酸类物质随着发酵的进行不断增加，是发酵后期阶段的主要挥发性风味物质。嗜酸乳杆菌发酵西瓜汁产生的挥发性风味物质较原汁的变化大于植物乳杆菌较原汁的变化，在后期都产生了一些刺激性气味较强的物质，所以最佳发酵时间应控制在24 h左右。

Abstract:

The volatile flavor compounds of watermelon juice (Black Beauty watermelon) fermented by Lactobacillus acidophilus (LA) and Lactobacillus plantarum (LP) were studied and compared to those of natural watermelon juice in this paper. The samples were prepared by using static-headspace solid phase microextraction (HS-SPME) method and the volatile flavor compounds of watermelon natural juice and 10-, 24-, and 48-hour fermented juice samples were measured by gas chromatography-mass spectrometry (GC-MS). One hundred twenty-four types of volatile flavor compounds were isolated and identified, including 29 alcohols, 19 aldehydes, 13 ketones, 22 acids, 11 hydrocarbons, 17 esters, and 13 other flavor compounds. Alcohols were the main volatile flavor compounds in natural watermelon juice and fermented juice. Their relative contents were up to 51% in the natural juice. The acid content increased continuously over the fermentation process and became the main volatile flavor compounds in the late stage of fermentation. The changes in the volatile flavor compounds between the natural watermelon juice and the juice fermented by LA were significant when compared to those between the natural watermelon juice and the juice fermented by LP. Some strong pungent substances were produced in the late stage of fermentation. Thus, the best fermentation time should be controlled at around 24 hours.