Hickman B Elliot, Janaswamy Srinivas, Yao Yuan
Whistler Center for Carbohydrate Research and Department of Food Science, Food Science Building, Purdue University, West Lafayette, Indiana 47907-1160, USA.
J Agric Food Chem. 2009 Jan 28;57(2):666-74. doi: 10.1021/jf8030698.
The overall objective of this research is to understand the impact of partial gelatinization and beta-amylase hydrolysis (beta-amylolysis) on the physicochemical properties of starch. Three starches (normal corn, waxy corn, and wheat) were chosen as test examples and thermally treated at 40% moisture content to up to 95 degrees C and then subjected to beta-amylolysis. The enzyme treatment resulted in over 10% maltose yield. Subsequent debranching analysis showed the production of chain stubs as short as having the degree of polymerization of 2 and 3, suggesting a thorough beta-amylolysis at certain branch locations. For starch samples subjected to partial gelatinization, polarized light microscopy shows reduced intensity of birefringence and differential scanning calorimetry shows reduced enthalpy change associated with gelatinization. Both indicate the reduced chain organization due to the treatment. Further, a substantial transformation of initial A-type crystalline structure to B- and V-types upon treatments is noticed from X-ray powder diffraction measurements. In addition, the rapid viscosity analysis (RVA) indicated a drastic viscosity reduction, increased peak temperature, and improved stability of pasting behavior due to hydrothermal treatments and beta-amylolysis. Overall, our results point out the possibility of obtaining modified starches having desirable stable pasting behavior by using a combined partial gelatinization and beta-amylolysis approach.
本研究的总体目标是了解部分糊化和β-淀粉酶水解（β-淀粉酶解）对淀粉物理化学性质的影响。选择三种淀粉（普通玉米、糯玉米和小麦）作为测试实例，在水分含量为40%的条件下加热至95℃，然后进行β-淀粉酶解。酶处理产生了超过10%的麦芽糖产量。随后的脱支分析表明，产生了聚合度低至2和3的短链残基，这表明在某些分支位置发生了彻底的β-淀粉酶解。对于经过部分糊化的淀粉样品，偏光显微镜显示双折射强度降低，差示扫描量热法显示与糊化相关的焓变降低。两者都表明处理导致链的有序性降低。此外，通过X射线粉末衍射测量发现，处理后初始A型晶体结构大量转变为B型和V型。此外，快速粘度分析（RVA）表明，由于水热处理和β-淀粉酶解，粘度急剧降低，峰值温度升高，糊化行为的稳定性提高。总体而言，我们的结果指出了通过结合部分糊化和β-淀粉酶解方法获得具有理想稳定糊化行为的变性淀粉的可能性。
