体外模拟胃肠消化乳酸菌发酵红枣汁的多酚类物质组成和抗氧化活性分析

Analysis of Polyphenol Composition and Antioxidant Activity of Jujube Juice Fermented by Lactic Acid Bacteria by in Vitro Simulated Gastrointestinal Digestion

摘要:

【目的】探究乳酸菌发酵红枣汁经体外模拟胃肠消化后的多酚类物质及抗氧化活性的变化规律。【方法】测定不同发酵阶段乳酸菌发酵红枣汁（原液）及其体外模拟胃肠消化液中的总酚、游离酚、结合酚的质量分数以及多酚类物质的组成、抗氧化活性，并对其进行比较。【结果】随着发酵时间的延长，原液、胃消化液的总酚质量分数均呈先上升后下降的趋势，肠消化液的总酚质量分数呈波动变化趋势，当发酵时间为48 h时，均达到最高值，分别为156.83、152.50、100.71 mg/100 g。随着发酵时间的延长，原液和胃消化液的游离酚质量分数均呈上升趋势，肠消化液的游离酚质量分数呈波动变化趋势；且胃消化液的游离酚质量分数在发酵16 h后高于原液和肠消化液，当发酵时间为64 h时，其最高值为110.78 mg/100 g，说明胃环境显著促进了游离酚的释放。此外，原液与肠消化液的结合酚在发酵前期显著积累。发酵提升了游离酚对DPPH、ABTS⁺自由基的清除率，胃、肠消化分别增强了游离酚对DPPH、ABTS⁺自由基的清除效果。随着发酵时间的延长，原液结合酚的DPPH和ABTS⁺自由基清除率呈波动变化趋势，胃消化液结合酚的DDPH自由基清除率呈上升趋势，肠消化液结合酚的ABTS⁺自由基清除率呈先上升后下降的趋势。与未发酵红枣汁游离酚组分相比，原液游离酚组分中芦丁、氢化肉桂酸、苯甲酸和水杨酸质量浓度分别增加了21.51%、54.41%、25.68%、28.62%；与原液游离酚组分相比，胃消化液游离酚组分中香草酸、没食子酸、丁香酸、原儿茶醛、木犀草苷等的质量浓度升高，说明发酵及胃消化促进了游离酚的释放。与未发酵红枣汁结合酚组分相比，原液结合酚组分中芦丁、反式阿魏酸、4-羟基苯甲酸等的质量浓度降低；与原液结合酚组分相比，胃消化液结合酚组分中芦丁、反式阿魏酸、原儿茶酸、原儿茶醛等的质量浓度降低；与胃消化液结合酚组分相比，肠消化液结合酚组分中反式阿魏酸、没食子酸、原儿茶酸的质量浓度分别提高了20.67%、54.03%、29.76%。【结论】乳酸菌发酵改善了红枣汁经胃肠消化后的多酚类物质组成及抗氧化活性，为开发功能性发酵枣制品提供了科学依据。

Abstract:

[Objective]This study aims to investigate the variation rules of polyphenolic substances and antioxidant activity of jujube juice fermented by lactic acid bacteria after in vitro simulated gastrointestinal digestion.[Method]The mass fractions of total phenols, free phenols, and bound phenols, as well as the composition of polyphenolic substances and antioxidant activity in the jujube juice fermented by lactic acid bacteria (original jujube juice) at different fermentation stages and in vitro simulated gastrointestinal digestive fluids were determined and compared.[Result]With prolonged fermentation time, the mass fractions of total phenolics in the original jujube juice and the gastric digestive fluid increased and then declined, while that in the intestinal digestive fluid exhibited fluctuating trends. At 48 h of fermentation, all samples reached their peak values: 156.83, 152.50, and 100.71 mg/100 g, respectively. With prolonged fermentation time, the mass fractions of free phenols in the original jujube juice and the gastric digestive fluid showed an increasing trend, while that in intestinal digestive fluid exhibited fluctuating changes. The mass fraction of free phenols in the gastric digestive fluid was higher than those in the original juice and intestinal digestive fluid after 16 h of fermentation, reaching a maximum value of 110.78 mg/100 g after 64 h of fermentation, indicating that the gastric environment significantly promoted the release of free phenols. In addition, bound phenols in the original juice and intestinal digestive fluid accumulated significantly in the early stage of fermentation. Fermentation improved the scavenging rates of free phenols against DPPH and ABTS⁺ free radicals, and gastric and intestinal digestion enhanced the scavenging effects of free phenols against DPPH and ABTS⁺ free radicals, respectively. With prolonged fermentation time, the DPPH and ABTS⁺ free radical scavenging rates of bound phenolics in the original jujube juice exhibited fluctuating trends, while those of the gastric digestive fluid showed an increasing trend in DPPH free radical scavenging activity. In contrast, the ABTS⁺ free radical scavenging capacity of bound phenolics in the intestinal digestive fluid followed an initial increase followed by a decline. Compared with the free phenol components in the unfermented jujube juice, the free phenol components rutin, hydrocinnamic acid, benzoic acid, and salicylic acid in the original jujube juice showed mass concentration increases of 21.51%, 54.41%, 25.68%, and 28.62%, respectively. Compared with the free phenol components in the original jujube juice, vanillic acid, gallic acid, syringic acid, protocatechuic aldehyde, and luteoloside among the free phenol components in the gastric digestive fluid showed increased mass concentrations, indicating that fermentation and gastric digestion facilitated the release of free phenols. Compared with the bound phenol components in the unfermented jujube juice, rutin, trans-ferulic acid, and 4-hydroxybenzoic acid showed decreased mass concentrations in the original jujube juice. Compared with the bound phenol components in the original jujube juice, rutin, trans-ferulic acid, protocatechuic acid, and protocatechuic aldehyde showed decreased mass concentrations in the gastric digestive fluid. Compared with the bound phenol components in the gastric digestive fluid, the intestinal digestive fluid showed increases of 20.67%, 54.03%, and 29.76% in the mass concentrations of trans-ferulic acid, gallic acid, and protocatechuic acid, respectively.[Conclusion]Lactic acid bacteria fermentation improves the polyphenol composition and antioxidant activity of jujube juice after gastrointestinal digestion, which provides a scientific basis for the development of functional fermented jujube products.