玉米缓慢消化淀粉理化性质研究

Physico-chemical Properties of Slowly Digestible Maize Starch

采用扫描电镜、X-射线衍射和布拉班德黏度仪等仪器,比较分析了缓慢消化淀粉及蜡质玉米淀粉(原淀粉)在结构、结晶度、黏度等理化性质方面的差异。研究结果表明:缓慢消化淀粉颗粒形态不规则、多棱角,颗粒疏松,无原淀粉的天然空隙;X-衍射峰位置发生改变,结晶度较原淀粉低,为29.65%;缓慢消化淀粉的糊化起始温度为72.5℃,在77.5℃时出现峰值其黏度值为41BU,缓慢消化淀粉的糊化开始时间较原淀粉略微提前,而达到峰值黏度的时间则较原淀粉长;观察偏光十字图片,发现原淀粉出现偏光十字,而缓慢消化淀粉则没有偏光十字;缓慢消化淀粉的比容积由原淀粉的1.8cm3/g,降低到1.25cm3/g,溶解度由原淀粉的14.78%减小到1.36%,透光率较原淀粉的12.2%降低到1.63%,白度也由原淀粉的97.2下降到81.6。

Differences in the physio-chemical properties of slowly digestible starch （SDS） prepared from maize and waxy maize starch （WMS） were investigated using scanning electron microscope （SEM）, X-ray diffraction, and Brabender viscometer. The data from SEM revealed that SDS granules were irregular and angular in shape and packing of stareh granules was loose. The X- ray diffraction patter showed significant alteration of SDS in comparison with native starch as well as the reduction in the crystallinity to 29.65%. The starch gelatinization of SDS was found to occur at 72.5 ℃ and the maximum viscosity reached 41 BU at 77.5 ℃. The starting gelatinization time of SDS was a little earlier than that of the native starch while the time required to reach the maximum viscosity was longer. Obvious polarized light cross was observed in native starch granules instead of SDS. The specific volume of SDS was reduced from 1.8 cm^3/g of the origin starch to 1.25 cm^3/g as well as the decrease of solubility from 14.78% to 1.36%. The transmittance and whiteness of SDS were found to be reduced from 12.2% of native starch to 1.63% and from 97.2 to 81.6, respectively.