Comparison of pasting properties measured from the whole grain flour and extracted starch in barley (<i>Hordeum vulgare</i> L.)

Pasting properties of barley starch are important characteristics from a processing standpoint. The isolation of starch form barley grains is time consuming thus the whole grain flour is always used. To compare pasting properties of starch with those of the whole grain flour, we used a Rapid Visco Analyser (RVA) to measure pasting properties of three types of samples: grain flour and starches isolated using two different extraction methods. We also investigated compositional, morphological and structural properties of the two starch samples. Significant differences in pasting properties were found among the three sample types, but most of the parameters of pasting properties displayed significant correlations between flour and starch. No significant differences were found in amylose/amylopectin ratio, granule morphology, granule size distribution and crystal structure between starches extracted using two different methods. However, the starch isolated from water homogenization had a higher protein content and lower total starch, amylose and amylopectin contents than the starch extracted with homogenized extraction under alkaline conditions. We concluded that the whole grain flour can be used to predict the pasting properties in breeding programs.从加工应用视角出发，大麦淀粉的糊化特性是一项关键品质指标。从大麦籽粒中分离淀粉的过程耗时较长，因此实际研究中通常直接采用全谷物面粉开展实验。为对比淀粉与全谷物面粉的糊化特性，本研究借助快速黏度分析仪（Rapid Visco Analyser, RVA）对三类样品的糊化特性进行测定：全谷物面粉，以及通过两种不同提取方法制备的淀粉。此外，本研究还对两种淀粉样品的组成、形貌与结构特性进行了表征分析。三类样品的糊化特性存在显著差异，但面粉与淀粉的绝大多数糊化特性参数均呈现显著相关性。两种不同提取方法制备的淀粉在直链淀粉/支链淀粉比值、颗粒形貌、粒径分布及晶体结构方面均无显著差异。不过，经水相均质法分离得到的淀粉，其蛋白质含量更高，而总淀粉、直链淀粉及支链淀粉含量均低于碱性条件下均质提取得到的淀粉。本研究最终得出结论：在大麦育种工作中，可通过全谷物面粉预测其淀粉的糊化特性。