After soaking, rice absorbs water and expands, which is conducive to the absorption of water by the internal starch and the homogeneous pasting of rice starch in the cooking process, thus shortening the cooking time. The higher the water absorption rate of rice after soaking, the higher the edible quality of rice after cooking.

Rice was immersed in different mass fractions of oligofructose, sorbitol and maltitol solutions, respectively, and it can be seen from Fig. 1 that the addition of all three sweeteners was able to increase the water absorption rate of rice compared to the control group.

At a soaking time of 5 min, rice water absorption was significantly (P < 0.05) increased by 41.23% and 34.93% under 1.6% oligofructose and 0.4% sorbitol treatments, respectively.

Among them, the water absorption of rice under 1.6% oligofructose, 0.4% sorbitol and 1.6% maltitol treatments was significantly increased by 11.18%, 13.16% and 12.94%, respectively, compared with the control group at the soaking time of 25 min, and the water absorption rate leveled off after 25 min of soaking time.

Sugar alcohol is obtained by replacing the aldehyde group with a hydroxyl group, and the multi-hydroxyl structure gives it the ability to combine with water and has a certain degree of water absorption. The hydroxyl group in maltitol interacts with water to form hydrogen bonds and snatch water molecules, so the addition of maltitol leads to a certain effect on the water absorption of rice in a short time. As the rice grains absorb water and swell, the gap on the surface of the rice increases, the internal starch rapidly absorbs water, and the water absorption rate tends to stabilize.