Water absorption behavior of starch: A review of its determination methods, influencing factors, directional modification, and food applications

Water absorption capacity (WAC) is one of the main aspects of starch research. This directly affects the performance of the starch products in the food industry. This study reviewed the previous studies methods for determining water absorption capacity (WAC), factors affecting WAC of starch and how to increase/decrease WAC of starch by directional modification. In addition, the application of starches with low or high WAC to the food products is discussed. Methods for determining the WAC of starch include the normal temperature, moisture adsorption isotherm, and water-phase contact angle methods. The WAC of starch is affected by the composition of starch, the microstructure of the granule surface, long-range crystalline structures, short-range ordered structures, and hydrophilic groups. In addition, it is reasonable to use physical, chemical, biomodification, or compound methods to directionally increase or decrease the WAC of starch to improve the properties of food products. Compared to the native starch, the increase in WAC ranged from 2% to 806% for starch with high WAC, and the decrease in WAC ranged from 4% to 663% for starch with low WAC. Currently, there are limitations to the industrial production of new starches with different WAC owing to the technical, equipment, and cost issues. Therefore, future studies should focus on these problems.