What changes occur when rice is cooked

Rice is an essential staple food in people's lives. It is a kind of food that people cannot live without at all times. Rice can only become cooked rice after it is cooked. The changes in rice are very great and rice is rich in nutrients. People who often eat rice may also have some health problems, because rice is a refined grain, so eating too much can easily cause constipation. What changes occur when rice is cooked?

Take the process of "cooking raw rice into cooked rice" for example. The basis for judging whether it is a chemical change is whether new substances are generated.

The composition of rice is relatively complex, containing starch, protein, cellulose, etc. During the cooking process, the internal structure of these substances changes. For example, the protein denatures and new substances are generated, which should be a chemical change.

The main component of raw rice is starch. The starch granules in raw rice will swell and burst when they absorb hot water. The appearance changes, but the starch does not change. However, a small amount of starch will hydrolyze into dextrin during the expansion, and may even further turn into simple sugars. From the process of cooking raw rice into cooked rice, there are both physical changes and chemical changes.

The rupture of starch granules is a physical change, and the conversion of starch into dextrin is a chemical change.

Cooked rice cannot become raw rice again, so chemical changes dominate. At the same time, water molecules enter the rice and the state of the rice changes, which should be considered a physical change. So strictly speaking, it is a process involving both chemical and physical changes.

Is it better to cook rice with cold water or hot water?

It is better to cook rice with hot water.

Here are the reasons:

Cooking rice in boiling water can shorten the cooking time and protect the vitamins in the rice. Since starch granules are insoluble in cold water, only when the water temperature is above 60°C will the starch absorb water, expand, burst and become a paste.

Rice contains a lot of starch. When cooking rice with boiling water, the temperature is about 100℃ (the boiling point of water). This temperature can make the rice cook quickly, shorten the cooking time, and prevent the vitamins in the rice from being destroyed by long-term high-temperature heating.