微波辅助过氧化氢半干法降解魔芋葡甘聚糖工艺优化及其特性研究

Optimization of Microwave-assisted Semidry Degradation of Konjac Glucomannan with Hydrogen Peroxide and Its Characteristics

魔芋葡甘聚糖(Konjac glucomannan,KGM)因相对分子质量大,水溶液黏度高,加工效率和应用范围受到限制。为探寻高效降低KGM黏度的方法以拓宽其应用市场,本研究以珠芽魔芋粉为原料,基于单因素实验,通过正交试验设计优化微波辅助过氧化氢氧化法(半干法工艺)制备低黏魔芋粉,并表征处理前后魔芋葡甘聚糖理化性质、结构和生理特性变化。结果表明:在微波功率700 W,过氧化氢浓度3%、液料比0.75:1 mL/g,混合均匀的反应物加热反应3 min,魔芋粉黏度由(6341.67±52.04)m Pa·s降低为(53.33±5.77)mPa·s,魔芋葡甘聚糖重均分子量由347.31 kDa减小至158.26 kDa,与未处理原料相比分别降低99.16%和54.43%。采用X射线衍射仪、紫外可见光谱仪、红外光谱仪、扫描电镜等解析氧化前后魔芋葡甘聚糖结构,发现氧化使KGM分子链断裂降解,结晶度减小,破坏微观片层结构的同时又保留了特征性基团,微波辅助过氧化氢降黏KGM的效果优于微波或过氧化氢单独处理KGM,降解产物表现出更好的脂肪结合能力与胆汁酸结合能力,进一步证实该方法可以高效、绿色、环保地制备低黏魔芋粉,为低黏KGM开发利用提供了依据。

The processing efficiency and application range of konjac glucomannan(KGM)are limited because of its high relative molecular mass and the high viscosity of its aqueous solution.In this study,konjac flour from Amorphophallus bulbifer was used as raw material to develop an efficient approach to reducing the viscosity of KGM and broadening its application market.Based on a single-factor test and an orthogonal experimental design for optimization,low-viscosity konjac flour was prepared by microwave-assisted hydrogen peroxide oxidation(a semidry process),and the changes in physicochemical,structural,and physiological characteristics of KGM were characterized before and after the treatment.The results showed that the viscosity of konjac flour decreased from 6341.67±52.04 to 53.33±5.77 mPa·s,and the weightaverage molecular weight of KGM decreased from 347.31 to 158.26 kDa when the uniformly mixed reactants were heated and reacted within 3 min at a microwave power of 700 W.The concentration of the hydrogen peroxide was 3%,and the liquid-material ratio was 0.75:1 mL/g.Compared to the untreated raw material,it decreased by 99.16%and 54.43%,respectively.Based on X-ray diffractometry,ultraviolet-visible spectrometry,infrared spectrometry,and scanning electron microscopy analyses of the KGM structure before and after oxidation,the oxidation of the KGM degraded the KGM molecular chain,decreased the crystallinity,and damaged the microscopic lamellar structure while retaining the characteristic groups.Moreover,the effect of the microwave-assisted hydrogen peroxide in decreasing the viscosity of the KGM was superior to that of the KGM treatment with the microwave or hydrogen peroxide only.The degradation products exhibited better fat-binding capacity and bile-acid-binding capacity.Therefore,KGM can be produced in a highly efficient,green,and ecofriendly manner,providing a rationale for the development and utilization of low-viscosity KGM.