Starch granules in water are stored at room temperature, 40? c、80？ c？ Gradually gelatinize, but after the dough is cooled, the gelatinization process will begin to reverse, and the age- starch molecules will begin to rearrange into a dense crystal structure, and at the same time lose water. The same is true of rice and steamed bread that have hardened for a long time.
Cookies will also age, but their water content is much lower than bread. When the surface water content is lower than 10%, it is not easy to age. Moreover, compared with bread, biscuits have a larger proportion of sugar and salt, and both sugar and salt are easy to absorb water, so biscuits will become soft rather than hard after being kept for a long time.
Pasta made of glutinous rice is not easy to harden because the main component of glutinous rice is amylopectin. Compared with amylose, its molecular structure has many branches and is easy to gelatinize, but it is not easy to age.
Extended data
Bakeries generally add food additives such as amylase to delay the aging process of bread. Preserved biscuits are generally dehumidified by desiccant, and homemade biscuits can be replaced by sugar cubes. Homemade bread can be sealed and frozen (note that it is not refrigerated) to inhibit bread aging.
Generally speaking, the aging of gelatinized starch should be avoided in food processing and cooking, but making good use of its principle can also "turn decay into magic"
In some special cases, such as the processing of vermicelli, vermicelli, lobster slices and other foods, because these foods will have strong toughness only after aging, they are not easy to break after heating, and their taste is rich, so they need to be aged in the production process.