脱乙酰基魔芋葡甘聚糖理化性质及其对凉皮质构和体外消化的影响

通过傅里叶变换红外光谱、X射线衍射图谱和扫描电子显微镜对不同脱乙酰度的脱乙酰基魔芋葡甘聚糖(deacetylatedkonjac glucomannan,DKGM)进行结构表征，并比较其黏度、持水性、热稳定性的变化；将高脱乙酰度的DKGM(脱乙酰度为72.70%)应用于凉皮制备，分析其对凉皮质构和体外消化特性的影响。结果表明，与KGM相比，DKGM在1 735 cm^-1处的乙酰基特征吸收峰减弱，表面变得粗糙，结晶度增加，热稳定性增加，黏度和持水性随脱乙酰度的增加而下降；添加高脱乙酰度的DKGM后，凉皮的硬度、咀嚼性和黏聚性整体均呈下降趋势，且其体外消化水解率降低，即添加高脱乙酰度的DKGM可提升凉皮口感及抗消化性，可为DKGM与淀粉复配体系在低血糖生成指数食品中的应用提供理论参考。

Physicochemical Properties of Deacetylated Konjac Glucomannan and Its Effects on the Quality and in Vitro Digestion Characteristics of Cold Noodles

In this work, the structures of deacetylated konjac glucomannan (DKGM) with different degrees of deacetylation were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM), and their viscosity, water-holding capacity (WHC) and thermal stability were evaluated and compared. The effects of DKGM with high degree of deacetylation (72.70%) on the texture and in vitro digestion characteristics of cold noodles were analyzed. The results showed that the characteristic absorption peak of acetyl group at 1 735 cm?1 in DKGM decreased, the surface became rough, the crystallinity and the thermal stability increased, and the viscosity and WHC decreased with the increase in the degree of deacetylation when compared with konjac glucomannan (KGM) (P < 0.05). After adding DKGM with high degree of deacetylation, the hardness, chewiness and cohesiveness of cold noodles showed a downward trend, and its in vitro digestibility decreased. In conclusion, addition of DKGM with high degree of deacetylation can improve the mouthfeel and digestion resistance of cold noodles, which may provide a theoretical basis for the application of DKGM and starch blends in low glycemic index foods.