关键词: 糯小麦；硬度指数；品质评价；主成分分析

Abstract: 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 water-absorbing 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 (≥10 μm) 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.

Key words: waxy wheat; hardness index; quality evaluation; principal component analysis