关键词: 小麦, 发芽程度, 降落数值, 品质, 加工特性, 馒头, 糊化特性

Abstract: To clarify the effect of pre⁃harvest sprouting on wheat quality and steamed bread processing quality under natural field condition，wheat materials in years suffering severe pre⁃harvest sprouting were used as experimental materials. The samples were classified into four groups based on grain falling number：grain falling number≤100 s（severe sprouting），100—200 s （mild sprouting），200—250 s，and ≥250 s. Variation trends of wheat quality indicators as well as quality types of wheat with different sprouting degrees were analyzed. Meanwhile，based on the flour falling number requirements for different types of flour processing，the materials were classified into four groups with different sprouting degrees：flour falling number<200 s，200—250 s，250—350 s，and ≥350 s. The steamed⁃bread quality of wheat with different sprouting degrees，correlations between steamed⁃bread quality and wheat quality indicators，and threshold values of flour pasting parameters for different flour processing types were investigated. The results showed that most wheat quality indicators exhibited high coefficients of variation in the year suffering severe pre⁃harvest sprouting. The volume weight，hardness index，protein content，wet gluten content，water absorption and extensibility were the lowest when the grain falling number was<100 s，while stable when the falling number was≥100 s. Dough energy，development time，stability time，resistance and maximum resistance decreased with the increase of sprouting degree，while degree of softening increased.The peak viscosity，trough viscosity，final viscosity，breakdown and setback of flour declined distinctly with the increase of sprouting degree，peak time decreased gradually，while pasting temperature increased slightly.The grain falling number was extremely significantly positively correlated with volumn weight，development time，stability time，energy，resistance，maximum resistance，peak viscosity，trough viscosity，breakdown，final viscosity，setback and peak time，and significantly negatively correlated with pasting temperature. Compared with wheat materials with stability time>10 min and of 7—10 min，wheat materials with stability time<7 min and <3 min were more susceptible to pre⁃harvest sprouting.The steamed bread taste evaluation results revealed that as sprouting degree increased，all quality scores decreased. Steamed bread made from wheat with flour falling number<200 s exhibited the lowest aspect ratio，elasticity，surface color，surface structure，internal structure，toughness，stickiness，and taste scores，along with the lowest total score. In contrast，the steamed bread made from wheat with flour falling number≥350 s achieved the highest total score，and the scores for wheat with flour falling number between 250 s and 350 s were close to those for wheat with flour falling numbers≥350 s.The score of steamed bread was significantly or extremely significantly positively correlated with the flour falling number，wet gluten content，development time，peak viscosity，trough viscosity，final viscosity，setback and peak time.The average values and ranges of flour pasting indicators for wheat with different flour falling numbers showed that the trough viscosity，final viscosity，and setback exhibited stepwise changes with different flour falling number ranges.Therefore，these three indicators could also serve as characteristic parameters for estimating wheat sprouting degree in flour processing. Specifically，when the trough viscosity ≤165 cP，final viscosity ≤438 cP，and setback ≤273 cP，the flour was unsuitable for bread，steamed bread and noodle production.

Key words: Wheat, Sprouting degree, Falling number, Quality, Processing characteristics, Steamed bread, Pasting properties