Physical phenomenon of frost-beaten vegetables being especially sweet.

The physical phenomenon of frost-beaten green vegetables is particularly sweet: condensation

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The first frost, one of the 24 solar terms, is around 65438+1October 23rd every year. The first frost solar term means that the weather is getting colder and the first frost appears. It is the last solar term in autumn, which also means that winter is about to begin. During the first frost, the farming custom is mainly to prevent frost. Although frost can cause freezing damage, it also contributes. Frosted vegetables will be sweeter.

Why do vegetables taste sweeter after frosting? Generally speaking, the temperature drops sharply after frosting because vegetables themselves are afraid of cold, which is a way for them to protect themselves from cell freezing. If explained by principle, it is also a common saying that most vegetables and even most vegetables contain starch and are not sweet.

And some vegetables taste bitter because they contain glucosinolates, which are usually bitter. After frosting, on the one hand, due to low temperature, the synthesis of glucosinolates in vegetables is delayed, and the bitterness is reduced to some extent.

On the other hand, starch in vegetables is hydrolyzed into maltose under the catalysis of amylase, and then converted into glucose under the action of maltase. Because glucose is soluble in water, frosted vegetables taste sweeter.

In addition, in the low temperature environment, the cells of green vegetables themselves will also be frostbitten, and substances such as sugar and amino acids in the cells will ooze from the inside, resulting in the sweetness of green vegetables.

Someone has done this experiment, looking for two pots, one filled with water and the other with sugar water. In the cold winter, they are all placed outdoors and observed after a period of time. When the clear water has frozen, the sugar water has not frozen.

The reason is that when glucose is dissolved in water, water is relatively difficult to freeze. Back to the vegetable itself, after a series of actions, the starch in the vegetable body becomes glucose, so that the water in the vegetable body is not easy to freeze, the cold tolerance is increased, and freezing injury is not easy to occur.