超高效液相色谱-串联质谱法鉴定和分析稻米中酚酸类化合物的组成及分布

米糠是谷物酚类物质的重要来源，其中多酚主要与膳食纤维结合，以结合态形式存在。本研究通过顺序酶法制备米糠不溶性膳食纤维结合酚（Insoluble Dietary Fiber-Bound Phenolic，IDF-BP），采用激光共聚焦显微镜、红外光谱、扫描电镜和X-射线衍射来表征IDF-BP结构变化，并对IDF-BP进行体外模拟胃肠消化和结肠发酵实验，随后对发酵物进行16S rRNA高通量测序的短链脂肪酸测定。结果表明，从米糠中制备得米糠IDF-BP得率为23.73%±0.008%，结合酚（Bound Phenolic，BP）含量为6.11±0.085 mg GAE/g DW，其中以阿魏酸含量最高为1.41±0.013 mg/g DW，其是典型的纤维素晶型，具有纤维素和半纤维素特征基团、酯键特征峰，以酯键形式与膳食纤维结合。肠道菌群多样性和菌群丰度结果显示，IDF-BP可通过降低肠道菌群多样性，下调肠道有害菌如拟杆菌属、考拉菌属，上调肠道有益菌如双歧杆菌属和艾克曼菌属，从而达到调节肠道菌群平衡的目的。同时也能促进短链脂肪酸（主要是乙酸、丙酸和丁酸）的产生以调节肠道pH。米糠IDF-BP兼具膳食纤维和多酚的特性，二者对肠道微生物和短链脂肪酸有较好的协同作用，有助于改善机体肠道环境，促进机体健康。

Antioxidant capacities and phenolic compounds of the husk,bran and endosperm of Thai rice

Rice bran is a major source of phenolic substances in cereals, in which phenolics mainly bound with dietary fiber in the form of conjugated state. In this study, rice bran insoluble dietary fiber-bound phenolic (IDF-BP) was prepared by sequential enzymatic method. The structure of IDF-BP was characterized by confocal laser scanning microscope (CLSM), Fourier transform infrared spectrometer (FT-IR), scanning electron microscope (SEM) and X-ray diffraction. The IDF-BP was subjected to simulated gastrointestinal digestion and colon fermentation in vitro, followed by 16S rRNA high-throughput sequencing of short-chain fatty acids. The results showed that the yield of rice bran IDF-BP was 23.73%±0.008%, the content of BP was 6.11±0.085 mg GAE/g DW, and the content of ferulic acid was the highest (1.41±0.013 mg/g DW). The IDF-BP was a typical cellulose crystal form of cellulose, which had both cellulose and hemicellulose characteristic groups and ester bond characteristic peaks, indicating that bound phenolic were bound to dietary fiber in the form of ester bond. The results of intestinal flora diversity and flora abundance showed that IDF-BP could regulate the balance of intestinal flora by reducing the diversity of intestinal flora, down-regulating intestinal harmful bacteria such as Bacteroides and Phascolarctobacterium, and increase intestinal beneficial bacteria such as Bifidobacterium and Akkermansia to achieve the goal of regulating the balance of gut microbiota. Additionally, it also had the ability to boost the production of short chain fatty acids (mainly acetic acid, propionic acid and butyric acid) to adjust intestinal pH. Rice bran IDF-BP had both the characteristics of dietary fiber and phenolics, and the two had a good synergistic effect on intestinal flora and short chain fatty acids, which would indicate that rice bran IDF-BP has the potential to improve the intestinal environment, thus achieving health benefits.