奶白花芸豆淀粉颗粒结构及理化特性研究

研究奶白花芸豆淀粉的颗粒结构及基本理化性质。结果表明：奶白花芸豆中直链淀粉含量较高，为37.1%；芸豆淀粉-碘的最大吸收光谱在波长617nm附近；芸豆淀粉颗粒较大的呈现卵形，颗粒大小分布较均匀。X射线衍射分析表明，该芸豆淀粉属于A型结晶结构；芸豆淀粉的粒度均呈光滑单峰型，分布曲线为正态分布，高峰出现在21.12～23.51μm处。芸豆淀粉颗粒偏光十字极其明显。芸豆淀粉糊凝沉性质表明该淀粉容易老化；芸豆淀粉糊的透光率在0～12h内没有显著变化，12～24h内透明度呈显著下降趋势，24～48h内没有显著变化。在质量浓度为2g/100mL时，析水率最高，冻融稳定性最差；差示扫描量热仪(DSC)分析结果表明，起始糊化温度为61.3℃，2个糊化峰值温度分别为73℃和74.6℃，糊化结束温度为83.4℃，糊化所需焓值为50.55J/g。淀粉糊质量浓度对其黏度具有显著影响，4g/100mL为该芸豆淀粉成糊临界质量浓度。

Granule Structure and Physico-chemical Properties of Light Speckled Kidney Bean Starch

The granule structure and basic physico-chemical properties of starch from light speckled kidney bean grown in Heilongjiang province were studied.The amylose content of light speckled kidney bean starch was 37.1%.The starch showed maximum absorbance at 617 nm after complexing with iodine.The starch granules were large and oval in shape and showed an uniform size distribution.The crystal structure of the starch,as indicated by X-ray analysis,belonged to type A.The granularity distribution showed a single smooth peak at 21.12-23.51μm and was in a normal manner.The birefringence cross of starch granules was very obvious and the starch revealed an obvious retrogradation property.In addition,the transparency of the starch gel had no significant change during 0-12 h and 24-48 h,while a significant change was observed during 12-24 h.The freeze-thaw stability was the weakest at the concentration of 2%.DSC results showed that the original pasting temperature was 61.3 ℃ and that the pasting peak temperatures were 73 ℃ and 74.6 ℃,respectively.The complete pasting temperature was 83.4 ℃ and the enthalpy required for complete pasting was 50.55 J/g.The concentration of the starch had a significant effect on viscosity.The critical concentration for the pasting of the starch was 4%.