测定直链淀粉含量的三种校准曲线法的比较

本文研究了脂肪,支链淀粉,介质pH和碘试剂浓度等因子对直链淀粉含量测定的影响。结果表明,由于脂肪的影响,使直链淀粉含量的测定值偏低,其影响在碱性介质中比在酸性介质中更为明显;不同脱脂方法的效果亦不同。支链淀粉的存在使测定值偏高,其干扰作用在酸性介质中较明显,而在碱性介质中被抑制。适当增大碱性试剂浓度可以在一定程度上补偿脂肪、介质的pH对直链淀粉含量测定的影响。比较三种校准曲线法的结果表明,标准样品校准法可以克服脂肪、支链淀粉等多种因子的影响,使测定的结果较为一致,具有较好的稳定性和重现性。

Comparison of Three Calibration Methods for Determination of Amylose Content in Milled-rice.

Factors affecting the determination of amylose content in milled rice were studied. The value of amylose content was reduced significantly by the residual lipids in milled-rice. It was even more marked in an alkaline medium. The efficency of defatting by several methods were compared. It was observed that interference of amylopecting in acidic medium resulting in higher value of amylose content, while in alkaline condition, the interference was checked. A higher concentration of iodine made some compensation to the interferences of factors such as lipids, pH value etc. Three widely used calibration methods were compared. The results showed that the values obtained by the curve from check samples were more stable and reproducible.