基于主成分分析的糯小麦品质评价和分类

Quality Evaluation and Classification of Waxy Wheat Varieties by Principal Component Analysis

为研究不同糯小麦品种综合品质的差异,以近10 a国内审定的17个糯小麦品种为实验材料,以普通小麦(硬质、混合型及软质)作为对照,分析其硬度指数、面团流变学特性和糊化特性。通过主成分分析和聚类分析对综合品质进行评价和分类。结果表明,17个糯小麦品种籽粒硬度指数为25.2~73.82,存在较大差异,其中硬质型比例为41.18%,硬度指数平均值为63.07,变异系数为11.20%;混合型和软质型比例均为29.41%。与普通小麦粉相比,糯小麦粉蛋白质含量较高(14.78%),直链淀粉含量较低(1.01%),表现出比普通小麦粉更好的加工特性,吸水率高(71.1 mL/100 g)、延伸性好(157.7 mm)、糊化时间短(3.59 min)、回生值低(290 cP)。主成分分析结果表明,淀粉粒体积平均粒径、A型(≥10μm)淀粉粒体积占比、最终黏度、回生值和低谷黏度是影响软质型和硬质型糯小麦品质差异的主要因素;而糊化特性、蛋白质含量、最大拉伸阻力和淀粉含量是影响混合型糯小麦品质差异的主要因素。17个糯小麦聚为3个类群,第Ⅰ类聚集了软质型和混合型综合评分最高的3个品种,第Ⅱ类聚集了6个硬质型品种,第Ⅲ类聚集了蛋白质含量和糊化特性指标均较低的8个品种。本研究为不同糯小麦品质评价、分类和核心品质指标的确定提供了一定依据。

The overall quality differences among different waxy wheat varieties was studied.Totally 17 waxy wheat varieties approved in China in the past decade and common wheat(hard,mixed and soft)were analyzed for hardness index,dough rheological properties and pasting properties.Comprehensive quality evaluation and classification were carried out by principal component analysis(PCA)and cluster analysis(CA).The results showed that grain hardness index significantly differed among waxy wheat varieties and ranged from 25.2 to 73.82.The proportion of the hard type was 41.18%,the average hardness index was 63.07,with a coefficient of variation of 11.20%.The proportions of the mixed and soft types were both 29.41%.Compared with ordinary wheat flour,waxy wheat flour had a higher protein content(14.78%)and a lower amylose content(1.01%),indicating better processing characteristics.In addition,waxy wheat flour had a high waterabsorbing rate(71.1%),good extensibility(157.7 mm),and short gelatinization time(3.59 min),and low setback(290 cP).The results of PCA showed that average particle size of starch granules,volume proportion of type A(≥10μm)starch granules,final viscosity,setback,and trough viscosity were the major factors affecting the quality difference between soft and hard-type waxy wheat,while gelatinization characteristics,protein content,maximum tensile resistance and starch content were the major factors affecting the quality difference of mixed waxy wheat.The 17 waxy wheat varieties were clustered into three categories by cluster analysis(CA),cluster-I including three varieties of soft and mixed-type wheat with the highest comprehensive score,cluster-II including six hard-type waxy wheat varieties,and cluster-III including eight waxy wheat varieties with low protein content and gelatinization characteristics.This study provides a basis for the quality evaluation,classification and core quality indicator determination of different waxy wheat varieties.