小麦不同部位在体外模拟消化过程中抗氧化活性的变化规律

采用体外模拟消化的方法对小麦不同部位(全麦、麸皮和精面)进行模拟胃肠消化实验,测定在模拟消化过程中抗氧化活性物质(以多酚表示)和黄酮释放量及总抗氧化活性的变化规律。结果显示:模拟胃消化过程中,与胃消化0 h相比,全麦、麸皮和精面的最大多酚释放量分别为其2.157、1.653和3.092倍,最大黄酮释放量分别为其1.825、1.574和3.179倍,最大ORAC值分别为其2.601、1.658和6.197倍。模拟肠消化过程中,与肠消化0 h和胃消化0 h相比,全麦、麸皮和精面的最大多酚释放量分别为其1.541、1.042、1.578和3.429、1.697、4.975倍,最大黄酮释放量分别为其1.428、1.026、1.688和2.421、1.570、4.913倍,最大ORAC值分别为其1.464、1.039、1.514和3.694、1.690、9.017倍。表明谷物结合多酚(如黄酮)在胃肠消化过程中,由于胃酸水解和胃肠蛋白酶酶解等消化作用由结合态转变成游离态多酚(黄酮),因而谷物结合多酚可以在胃肠道消化吸收。

Changes in Antioxidant Activity in Different Parts of Wheat during In Vitro Simulated Digestion

Different parts of wheat (whole wheat flour, bran, and refined flour) were subjected to simulated gastrointestinal digestion in vitro, to determine changes in the release of active antioxidant substances (polyphenols) and flavonoids, as well as total antioxidant capacity. The results showed that the maximum quantities of polyphenols and flavonoids released from whole wheat, bran, and refined flour during gastric digestion were 2.157-, 1.653-, 3.092-, and 1.825-, 1.574-, 3.179-times the values at 0 h, respectively. Similarly, the maximum oxygen radical absorption capacity (ORAC) values for whole wheat, bran, and refined flour were 2.601-, 1.658-, and 6.197-times the values at 0 h, respectively. On the other hand, the maximum quantities of polyphenols released from whole wheat, bran, and refined flour during in vitro simulated intestinal digestion were 1.541-, 1.042-, and 1.578-times the values at 0 h of intestinal digestion, and 3.429-, 1.697-, and 4.975-times the values at 0 h of gastric digestion, respectively. Additionally, the maximum quantities of flavonoids released from whole wheat, bran, and refined flour were 1.428-, 1.026-, and 1.570-times the values at 0 h of intestinal digestion, and 2.421-, 1.570-, and 4.913-times the values at 0 h of gastric digestion, respectively. Similarly, the maximum ORAC values for whole wheat, bran, and refined flour were 1.464-, 1.039-, and 1.514-times the values at 0 h of intestinal digestion, and 3.694-, 1.690-, 9.017-times the values at 0 h of gastric digestion, respectively. The results show that the polyphenols (such as flavonoids) bound to grains were converted to free polyphenols from the bound form due to gastric acid and enzymatic hydrolysis via gastrointestinal protease during gastrointestinal digestion. Thus, polyphenols bound to grains can be digested and absorbed in the upper gastrointestinal tract.