在红枣汁中乳酸菌、酵母菌单一及偶联发酵特征物质差异分析

Analysis of Differential Substances in Pure and Mixed Culture Fermentation of Jujube Juice by Lactic Acid Bacteria and Yeast in Jujube Juice

摘要:

该试验以红枣为原料，研究乳酸菌、酵母菌单一及偶联发酵对枣汁总糖、总酸、总酚、黄酮和酒精含量的影响，使用液相色谱-质谱联用（Liquid Chromatograph-Mass Spectrometer，LC-MS）技术进行游离型酚酸差异分析，气相色谱-离子迁移谱联用（Gas Chromatography-Ion Migration Spectrum，GC-IMS）技术进行挥发性有机物差异分析。结果表明，原枣汁无论是单一菌种发酵还是混合菌种发酵，总糖、黄酮含量降低，总酸、总酚含量、酒精度均增加，反式阿魏酸、4-羟基苯甲酸、氢化肉桂酸、香草酸、苯甲酸、丁香酸增加；酵母菌发酵枣汁总酚、黄酮、酒精度、苯丙氨酸、儿茶素、表儿茶素、丁香酸 、芥子酸含量均高于乳酸菌发酵枣汁，总酸含量低于乳酸菌发酵枣汁；经混菌偶联发酵，糖类物质降解效率、产酸效率、总酚生成率、黄酮留存率以及产酒精效率更高；游离型酚酸反式阿魏酸、反式肉桂酸、香草酸、没食子酸、对香豆酸、苯甲酸、原儿茶酸、咖啡酸、丁香酸较单菌发酵样品高；挥发性成分53种，包括11种醇类化合物、9种酯类化合物、8种酮类化合物、8种醛类化合物、2种酸类化合物、2种吡嗪吡嗪类化合物，混菌发酵样品中风味物质酯类、醇类、醛类分别占17.2%、58.2%、和1.3%，酯类和醛类显著高于乳酸菌发酵样品、酵母菌发酵样品及原枣汁，香味浓烈，因此采用酵母菌、乳酸菌混合发酵，可以有效地增强发酵枣汁的品质，丰富口感，该研究为推动混菌发酵在红枣酵素发酵生产行业的应用，提供相应的理论基础和科学实践依据。

Abstract:

Here, the effects of pure and mixed culture fermentation by lactic acid bacteria and yeast on the total sugar, total acid, total phenol, flavonoid, and alcohol contents of jujube juice were examined. The analysis of the difference in free phenolic acids was performed with the help of Liquid Chromatography-Mass Spectrometry (LC-MS). The differences in volatile organic compounds were analyzed using Gas Chromatography-Ion Mobility Spectrometry (GC-IMS). The results showed that, regardless of pure and mixed culture fermentation, the total sugar and flavonoid contents decrease, while the total acid, total phenol, and alcohol contents increase. Furthermore, the contents of trans-ferulic acid, 4-hydroxybenzoic acid, hydrocinnamic acid, vanillic acid, benzoic acid, and syringic acid increase. Contrarily, yeast fermentation results in higher contents of total phenols, flavonoids, alcohol, phenylalanine, catechin, epicatechin, syringic acid, and sinapic acid in jujube juice but a low total acid content compared to lactic acid bacteria fermentation. The carbohydrate degradation efficiency, acid production efficiency, total phenol production rate, flavonoid retention rate, and alcohol production efficiency were higher after mixed culture fermentation. Similarly, mixed culture fermentation produces higher contents of free phenolic acids, including trans-ferulic acid, trans-cinnamic acid, vanillic acid, gallic acid, p-coumaric acid, benzoic acid, protocatechuic acid, caffeic acid, and syringic acid than does pure culture fermentation. A total of 53 volatile components were identified, including 11 alcohols, 9 esters, 8 ketones, 8 aldehydes, 2 acids, and 2 pyrazines. In mixed culture fermentation samples, flavor esters, alcohols, and aldehydes account for 17.2%, 58.2%, and 1.3%, respectively. The contents of esters and aldehydes in mixed culture fermentation samples are significantly higher than those in pure culture fermentation samples and original jujube juice samples, resulting in a strong flavor. Therefore, mixed culture fermentation using yeast and lactic acid bacteria can effectively enhance the quality and enrich the taste of fermented jujube juice. This study provides a theoretical, scientific, and practical basis for promoting the application of mixed culture fermentation in the jujube fermentation and production industry.