湿热处理前后中国菰米淀粉结构、理化和消化特性的变化

Changes in Structural, Physicochemical, and Digestive Properties of Chinese Wild Rice Starch before and after Heat-moisture Treatment

摘要:

该研究探讨了湿热处理（Heat-moisture Treatment, HMT）对不同水分含量中国菰米淀粉（HMT-15、HMT-20、HMT-25、HMT-30）结构、理化和消化特性的影响。结果表明：HMT 导致菰米淀粉颗粒形态遭到不同程度的破坏，淀粉结晶结构改变，短程有序性降低，且随着体系中水分含量的增加，该现象更为明显。淀粉的粒径由0.84 μm增大至5.14 μm，相对结晶度从26.29%下降到20.65%。菰米淀粉的溶解度由19.25%提高到24.01%，膨胀度由15.13 g/g降低到12.11 g/g。冻融稳定性呈现先升后降的趋势，其中HMT-20析水率（35.12%）达到峰值，而HMT-30析水率（13.12%）最低，且显著低于天然菰米淀粉（19.66%）。糊化特性结果显示，HMT能提高菰米淀粉的糊化温度，降低米糊体系的黏度和回生值。体外消化结果显示，随着体系中水分含量的增加，菰米淀粉的快速消化淀粉（Rapidly Digestible Starch, RDS）含量显著降低，抗性淀粉（Resistant Starch, RS）含量显著增加，其中HMT-30具有最低的RDS（20.49%）和最高的RS（28.66%）。高水分体系下的湿热改性菰米淀粉表现出良好的冷热稳定性、抗老化性以及抗消化性，研究结果可为菰米淀粉的深加工及推广提供新的思路。

Abstract:

Here, the effects of heat-moisture treatment (HMT) on the structural, physicochemical, and digestive properties of Chinese wild rice starches with different moisture contents (HMT-15, HMT-20, HMT-25, HMT-30) were investigated. Results showed that under conditions of HMT, the morphology of starch granules in wild rice was damaged to varying degrees, the crystalline structure of starch was altered, and short-range ordering was reduced; these phenomena became more pronounced as the moisture content of the system increased. The particle size of starch increased from 0.84 μm to 5.14 μm, and the relative crystallinity of starch decreased from 26.29% to 20.65%. The solubility of starch derived from Chinese wild rice increased from 19.25% to 24.01%, and the swelling degree decreased from 15.13 g/g to 12.11 g/g. The freeze-thaw stability of this starch tended to first increase and then decrease. The syneresis rate of HMT-20 (35.12%) was the highest, while that of HMT-30 (13.12%) was the lowest (significantly lower than even that of natural wild rice starch (19.66%)). Analysis of the gelatinization properties showed that HMT increased the gelatinization temperature of wild rice starch and reduced the viscosity and retrogradation of the wild rice paste system. In vitro digestion showed that in Chinese wild rice starch, the content of rapidly digestible starch (RDS) decreased significantly, while that of resistant starch (RS) increased significantly with increasing moisture content in the system; HMT-30 had the lowest RDS content (20.49%) and the highest RS content (28.66%). Chinese wild rice starch exposed to HMT under conditions of high moisture exhibited robust stability in both hot and cold conditions, and good aging resistance and digestive resistance. The results of this study would provide new ideas for the further processing and promotion of Chinese wild rice starch.