三种改性方法对青香蕉淀粉物化性质的影响

为了探求一种既尽可能保留青香蕉淀粉的天然特性，又能改善其加工特性的改性方法，对比了复合酶法、乳酸发酵法和挤压膨化法对青香蕉淀粉特性的影响。结果表明：三种改性方法中，复合酶法能够显著提高抗性淀粉的质量分数；通过比较三种改性淀粉的理化特性，复合酶法和乳酸发酵法使结晶度由18.13%分别增加到20.19%和22.06%，而挤压膨化法使结晶度大幅下降至2.16%。复合酶法淀粉的分子解聚程度低，能较好保持原淀粉的颗粒形态，且有助于提高淀粉糊的热稳定性、冷稳定性和凝沉性。而乳酸发酵法和挤压膨化法使热稳定性降低，凝沉性减弱，但能够提高冷稳定性；加工特性研究表明，复合酶法对香蕉原淀粉的色泽影响较小，有助于改善淀粉糊的透明度，提高香蕉淀粉的感官品质。挤压膨化改性淀粉在透明度、溶解度和吸水性方面均有所改善。而乳酸发酵改性对冻融稳定性的影响较小。综上而言，复合酶法是较理想的改性方法。

Effects of Three Modification Methods on the Physicochemical Properties of Native Banana Starch

The effects of three modification methods including compound enzymolysis, lactic acid fermentation and extrusion on physicochemical and processing characteristics were analyzed, in order to find a method that can retain the natural advantages of banana starch and improve the processing performance. The results showed that compound enzymatic modification could increase the content of resistant starch （RS） significantly. Compound enzymolysis and lactic acid fermentation increased the crystallinity of banana starch from 18.13% to 20.19% and 22.06% respectively, but the crystallinity of the starch modified by extrusion decreased to 2.16%. The effect of compound enzymatic modification could preserve the particle morphology of native banana starch which was helpful to improve the thermal stability, cold stability and the retrogradation. Besides, the compound enzymolysis had less effect on color that improved the transparency of starch paste. Lactic acid fermentation and extrusion reduced the thermal stability and retrogradation, but helped to improve the cold stability. Extrusion could also improve the transparency, solubility and hygroscopocity. The three kinds of modification methods decreased freezing and thawing stability, but the lactic acid fermentation had less effect on it. In a word, the compound enzymolysis was an ideal modification method.