Why are grapes sweet and rice not sweet?

Grapes are sweet because they contain a high amount of soluble sugars, such as glucose and fructose. These sugars are easily broken down by the body, which converts them into energy. Rice, on the other hand, contains a high amount of starch, which is a complex carbohydrate. Starch is not as easily broken down by the body, which means that it takes longer to convert it into energy. This is why grapes taste sweet, while rice does not.