鲜木薯抗性淀粉的制备与性质

为了提高木薯抗性淀粉的含量，该研究以鲜木薯湿淀粉为原料，采用压热-酶法制备抗性淀粉，通过单因素试验和响应面分析，获得抗性淀粉的最佳制备条件为：淀粉乳浓度10%、压热时间80 min、压热温度120℃、耐热α-淀粉酶添加量1 U/g、耐热α-淀粉酶作用时间15.75 min，普鲁兰酶添加量0.83 U/g，普鲁兰酶作用时间5.86 h、超声波处理时间2 min。在此条件下抗性淀粉的质量分数是15.48%。电镜试验表明淀粉颗粒经压热-酶法处理后表面形态发生变化；X-射线衍射表明抗性淀粉的结晶类型为B型，结晶度增加；体外消化模拟试验表明：与原淀粉相比，抗性淀粉消化特性降低。该研究可为抗性淀粉的工业化生产和应用提供参考。

Preparation and properties of resistant starch from fresh cassava

Abstract: Many studies have shown that resistant starch has health benefits such as preventing colon cancer, reducing the risk of ulcerative colitis, increasing absorption of minerals, inhibiting fat accumulation and hypoglycemic effects. In this study, the cassava starch was used as raw material. The resistant starch was prepared by autoclaving assisted enzyme treatment. To improve the content of resistant starch, the parameters of enzyme treatment that include adding amounts of α-amylase, reaction time of α-amylase, adding amounts of pullulanase and reaction time of pullulanase were optimized with a response surface methodology. The F-value of 57.58 implies the model is significant. The Lack of Fit F-value of 1.66 implies the Lack of Fit is not significant relative to the pure error. The Pred R-Squared of 0.9156 is in reasonable agreement with the Adj R-Squared of 0.9659 and the R-Squared is 0.9829. This model can be used to navigate the design space. The optimized conditions were that when 10% of the starch slurry concentration was autoclaved at 120℃ for 80min, added 1U α-amylase per gram of starch to react 15.75 min at 95℃, debranched with 0.83U pullulanase per gram of starch at 55℃ for 5.86h, then treated with ultrasonic for 2min, and finally retrograded at 4℃ for 24h to improve resistant starch formation, the content of resistant starch increased to 15.48%. Compared with raw starch, the granule appearance of resistant starch changed under scanning electron microscopy. X-ray diffraction showed that the cassava starch had an A type pattern with sharp peaks at 15°, 17°, 18° and 23°. However, the resistant starch had a B type pattern with sharp peaks at 17° and 22°. The crystallinity of resistant starch improved with increasing resistant starch content. The in vitro digestion results indicated that total carbohydrate digestion products were decreased with increasing resistant starch content and that digestion rates were decreased with increasing incubation time. In first three hours, the concentration and activity of α-amylase solution were high and the binding sites between starch molecules and α-amylase were enough, so the total carbohydrate digestion products of all samples were increased sharply in the initial stage. After three hours, the digestion products were increased slightly and the digestion rates slowed down. This was mainly because starch molecules were hydrolyzed into a small molecular chain and the binding sites were decreased.