面粉的吸水率是指四个面团和成面团时的最大加水量, 以百分比表示 (%). 吸水率直接影响食品的出品率. 适用于馒头、面包等面制品, 吸收的水越多, 相同面粉重量的馒头和面包的数量较多的是. 影响面团吸水率的因素很多: 主要是面粉颗粒分布, 蛋白质含量, 非淀粉多糖, 淀粉损伤, 含水量, ETC. 其中最重要的因素有3个: 蛋白质含量, starch damage and non-starch polysaccharides.

The protein in flour is categorized as water soluble protein and water insoluble protein (gluten protein). Researches show that water soluble protein and water insoluble protein both absorb water, but the water absorption of water insoluble protein (gluten protein) is more important and has a great bearing on dough’s water absorption rate. When water insoluble protein absorbs water, it can form a viscoelastic network structure unique to dough. Starch damage means the damage of starch’s outer cell membrane caused by mechanical grinding and pressing during milling process. Damaged starch is decomposed into dextrin, maltose and glucose under the effect of acid and enzyme, which play an important role in water absorption during dough’s fermentation and baking periods. The water absorption rate of damaged starch can reach 200%, which is five times that of complete starch granules.

Obvious negative correlation exists between gluten content and dough’s water absorption rate; no correlation exists between water holdup rate and dough’s water absorption rate; while obvious positive correlation exists between damaged starch content and dough’s water absorption rate.

As damaged starch influences dough’s water absorption rate to great extent, damaged starch content is high and dough’s water absorption rate is high, and thus the production rate of flour products is high. Therefore, damaged starch content should be increased properly in order to improve the production rate of flour products. However, researches show that high starch damage rate will affect product quality, so damaged starch contents should be properly adjusted according to different usages of tailored flours.