乳酸菌发酵对荞麦壳多酚组成及胃肠消化、酵解特性的影响

Effects of Lactobacillus plantarum Fermentation on the Phenolic Compositionand in Vitro Digestion and Fermentation Properties of Buckwheat Hulls

目的:探究乳酸菌HH-LP56发酵荞麦壳的酚类组成、胃肠道消化及结肠酵解特性。方法:用乳酸菌发酵处理荞麦壳,根据发酵过程中pH、总酚含量及抗氧化活性变化,筛选代表性样品,采用液相色谱法分析代表性样品的主要酚类物质结合方式及含量;采用Infogest 2.0体外胃肠消化,评价酚类的生物可及情况;进一步接种人粪便模拟结肠厌氧酵解,分析产气量、pH和短链脂肪酸(SCFA)。结果:乳酸菌发酵6 h(LP-6h)后总酚含量显著增加,发酵24 h(LP-24h)后进一步增加,并在发酵48 h(LP-48h)时总酚含量达到最高水平(7.32 mg/g)。分析未发酵(Raw)和发酵荞麦壳的酚类组成和存在形式发现,LP-6h,LP-24h和LP-48h中游离态没食子酸(142.88~145.87 mg/kg)和原儿茶酸(103.30~113.61 mg/kg)的含量显著高于Raw组(P<0.01),且肠道生物可及性明显增加。体外接种5位志愿者粪便菌群模拟结肠酵解发现,未发酵和发酵荞麦壳的产气量、主要SCFA和支链脂肪酸(BCFA)含量总体上均较为接近。其中3位志愿者的粪便微生物酵解荞麦壳48 h后,总SCFA含量均显著高于未发酵荞麦壳(P<0.01或P<0.05)。结论:乳酸菌发酵能有效改善荞麦壳的胃肠消化和酵解特性,研究结果将为乳酸菌发酵用于荞麦壳精深加工提供理论依据。

Objective:This study investigated the phenolic composition and in vitro gastrointestinal digestion and fermentation characteristics of buckwheat hulls(BH)fermented by Lactobacillus plantarum HH-LP56.Methods:The temporal changes in pH value,total phenolic content,and antioxidant activity during L.plantarum fermentation of BH were analyzed,and several representative fermented samples were selected to evaluate the phenolic compositions by HPLC.The bioaccessibility of BH phenolics were evaluated using in vitro gastrointestinal digestion model named Infogest 2.0,and the pH,gas and SCFA production were analyzed to characterize the fermentation properties of BH.Results:The fermented BH at 6 h(LP-6h)significantly increased the total phenolic content,which further increased in the fermented BH at 24 h(LP-24h).The total phenolic content reached the highest level(7.32 mg/g)at 48 hours of fermentation(LP-48h).Analysis of the composition and forms of individual phenolics in unfermented(Raw)and fermented BH revealed that the content of free gallic acid(ranging between 142.88 and 145.87 mg/kg)and protocatechuic acid(ranging between 103.30 and 113.61 mg/kg)in LP-6h,LP-24h,and LP-48h was significantly higher than that in the Raw group(P<0.01),as a result,the intestinal bioavailability of gallic acid and protocatechuic acid was significantly increased.Through the inoculation of 5 volunteers'fecal microbiota to simulate colonic fermentation,the results suggested that the gas production,three main SCFA and BCFA contents of Raw and fermented BH were similar.However,within three volunteers,the total SCFA content of LP-6h,LP-24h,and LP-48h was significantly higher than that of Raw BH after 48 hours fermentation(P<0.01 or P<0.05).Conclusion:L.plantarum fermentation can effectively improve the gastrointestinal digestion and fermentation characteristics of BH,providing a theoretical basis for the applications in the deep and value-added processing of BH.