核桃花多糖提取工艺优化及对肠道菌群的调节作用

Optimization of extraction process for walnut flower polysaccharides and its regulatory effect on gut microbiota

中文关键词:  核桃花，多糖，提取，发酵，短链脂肪酸

英文关键词:walnut flower  polysaccharides  extraction  fermentation  short-chain fatty acids

中文摘要:

      目的 优化核桃花多糖的提取工艺, 探究其潜在的肠道菌群调节作用。方法 采用酶解辅助低共熔溶剂法提取多糖。在单因素基础上, 以含水量、酶浓度、提取温度、液料比为变量, 通过响应面实验优化工艺参数; 利用傅里叶红外光谱和紫外分光光度计初步探究其结构, 并进一步开展体外发酵实验, 分析核桃花多糖对高脂血症相关肠道菌群多样性、结构及短链脂肪酸(short-chain fatty acids, SCFAs)生成的影响, 结合相关性热图解析菌群与SCFAs的关联。结果 核桃花多糖最优提取工艺为含水量30%、酶浓度2%、提取温度50 ℃、液料比21:1 (mL:g), 提取率达(5.91±0.42)%, 所建模型可有效预测工艺效果, 经测定多糖含量为88.03%, 含有糖醛酸基团、吡喃环结构, 且同时存在α-型与β-型两种糖苷键。体外发酵实验表明核桃花多糖可明显改善肠道菌群多样性及结构组成, 促进有益菌增殖, 抑制致病菌生长, 同时提升乙酸、丙酸、丁酸等SCFAs产量; 相关性分析表明上述有益菌属与核心SCFAs呈强正相关, 可作为肠道有益代谢恢复的生物标志物。结论 核桃花多糖提取工艺可行, 具有良好的肠道菌群调节作用, 为其在肠道健康领域的功能食品开发提供理论依据。

英文摘要:

      Objective To optimize the extraction process of walnut flower polysaccharides and explore its potential regulatory effect on intestinal flora. Methods Walnut flower polysaccharides was extracted by enzyme-assisted deep eutectic solvent method. Based on single-factor experiments, response surface methodology was employed to optimize the extraction parameters with moisture content, enzyme concentration, extraction temperature and liquid-to-solid ratio as independent variables. Fourier transform infrared spectroscopy and ultraviolet spectrophotometry were employed for the preliminary structural characterization of walnut flower polysaccharides. Furthermore, in vitro fermentation experiments were conducted to analyze the effects of walnut flower polysaccharides on the diversity, structure and short-chain fatty acids (SCFAs) production of hyperlipidemia-related intestinal microbiota. The correlation between microbiota and SCFAs was elucidated using a correlation heatmap. Results The optimal extraction conditions were determined as follows: moisture content of 30%, enzyme concentration of 2%, extraction temperature of 50 ℃, and liquid-to-solid ratio of 21:1 (mL:g). Under these conditions, the extraction yield of walnut flower polysaccharides reached (5.91±0.42)% and the established model exhibited reliable predictive ability. The polysaccharide content of the extracted walnut flower polysaccharides was determined to be 88.03%. Structural characterization indicated that WFP contained uronic acid groups and pyranose ring structures, as well as both α- and β-glycosidic bonds. In vitro fermentation results showed that walnut flower polysaccharides significantly improved the diversity and structural composition of the intestinal microbiota, promoted the proliferation of beneficial bacteria, inhibited the growth of pathogenic bacteria and increased the production of SCFAs including acetate, propionate and butyrate. Correlation analysis indicated that the aforementioned beneficial genera were strongly positively correlated with core SCFAs, which could serve as biomarkers for the recovery of intestinal beneficial metabolic functions. Conclusion The extraction process of walnut flower polysaccharides is feasible and walnut flower polysaccharides exhibits regulatory effects on the intestinal microbiota. This study provides a theoretical basis for the development of functional foods in the field of intestinal health.