改性方法对大蒜秸秆总膳食纤维功能特性的影响

Effect of Modified Methods on the Functional Properties of Total Dietary Fiber from Garlic Straw

为增强大蒜秸秆膳食纤维的生理功能,研究不同改性方法对其总膳食纤维(TDF)的主要功能及微观结构特征的影响。分别利用超声、酶解、水浴及超声辅助酶解法对大蒜秸秆的TDF进行改性和提取,通过吸水性、吸油性、膨胀能力、吸附葡萄糖及胆固醇能力等来评价其功能特性,并用扫描电镜观察其结构变化。结果表明:水浴法得到的TDF得率最高,超声辅助酶解法的TDF得率最低,然而其可溶性膳食纤维含量最高达到12.59%;超声及超声辅助酶解法得到的TDF持水性、持油性及膨胀力均显著优于酶解和水浴法;4种方法中,超声辅助酶解预处理得到的TDF对胆固醇的吸附量最大,为12.46 mg/g;对于葡萄糖吸附能力,超声辅助酶解与超声作用所得TDF的吸附量均较高,且这两种方法之间差异不显著(P>0.05);电镜观察TDF的结构发现,超声辅助酶解处理使TDF的微观结构变得更加疏松,其表面呈现蜂窝状,表现出较强的吸附性。研究结果表明超声辅助酶解法为大蒜秸秆膳食纤维主要功能改性的最佳方法。

This study evaluated the effects of ultrasound, enzymatic hydrolysis, water extraction and ultrasonic assisted enzymatic hydrolysis on the functional and structural properties of total dietary fiber（TDF） from garlic straw. The water holding capacity（WHC）, oil holding capacity（OHC）, water swelling capacity（WSC）, cholesterol and glucose absorption capacities were determined. The surface morphology of TDF was observed by scanning electron morphology（SEM）. Results suggest that when garlic straw was pretreated by ultrasonic assisted enzymatic hydrolysis method, the TDF yield was the lowest. However, SDF content of TDF prepared with ultrasonic assisted enzymatic hydrolysis pretreatment achieved the highest value of 12.59%. It was found that higher WHC, OHC and WSC were observed when TDF prepared with ultrasound and ultrasonic assisted enzymatic hydrolysis pretreatments. The highest cholesterol absorption capacity of TDF was obtained by the pretreatment of ultrasonic assisted enzymatic hydrolysis and the value was 12.46 mg/g.For glucose absorption, TDF from ultrasound and ultrasonic assisted enzymatic hydrolysis both showed high capacity, and there were no differences between these two methods（P〉0.05）. SEM images demonstrated that the surface of TDF obtained by ultrasonic assisted enzymatic hydrolysis pretreatment was rough and collapsed, which illustrated the good functional properties. Therefore, it can be concluded that TDF from garlic straw with ultrasonic assisted enzymatic hydrolysis pretreatment has the higher potential to be applied as a functional ingredient in food products.