Why do you say "frosted vegetables are especially sweet"?

0 1 first frost can delay the synthesis of glucosinolates in Chinese cabbage and reduce the bitterness. In the first frost, in order to resist the cold, vegetables will accumulate more carbohydrates, and the starch in vegetables will be hydrolyzed into maltase, which will be converted into glucose through the action of maltase, so vegetables will have a sweet taste. In addition, in the weather below the first frost of 4℃, the vegetables will be frozen, forming a sweet, soft and waxy taste.

From an ancient poem? Many first frost Xi vegetation zero? But you know what? There is another saying in our country? Frosted vegetables are especially sweet? . It means that frosted vegetables taste sweet and waxy. Why?

When the first frost comes, the temperature is lower and the dew on the surface condenses into frost. Frost is the condensation phenomenon of water vapor near the ground when the temperature is very low, that is, the crystallization of water vapor. There is an important condition for frosting: the temperature should be close to 0℃.

Folk common name? Frosting? This is frost, which usually appears on a clear moonlit night. On a clear night, the earth is like a quilt, the temperature drops sharply and the heat dissipates quickly. At this time, some water vapor near the ground will condense on streams, bridge decks, leaves and soil, forming a thin layer of white crystals. In the early morning of the cold season, when we go out, we can find that many things around us are covered with frost crystals.

The fresh and sweet taste of frosted vegetables has scientific basis. First of all, vegetables contain glucosinolates, which are usually bitter. We will try them a little. However, the arrival of cooling weather such as the first frost will delay the synthesis of glucosinolates in vegetables. At the same time, the first frost occurs at extremely low temperature, and the respiration of low-temperature vegetables is weakened at night in winter. In order to resist cold, carbohydrates produced by photosynthesis will accumulate more in plants during the day, and starch in vegetables will be hydrolyzed into maltase under the action of amylase in plants, and then converted into glucose under the action of maltase. Glucose is easily soluble in water, so vegetables are sweet. In addition, in the weather below the first frost of 4℃, Chinese cabbage will be frozen, the cell membrane will rupture, and substances such as sugar and amino acids in the cells will also ooze out, forming a sweet and soft taste. Therefore, the vegetables after the first frost taste better. In life, delicious frosted vegetables include mustard, radish, Chinese cabbage, Chinese cabbage, lettuce, lettuce, Shanghai green and so on.

Frosted fruit also has a special taste, the most distinctive is the red persimmon in autumn. Persimmons generally mature completely before and after the first frost. At this time, persimmon has thin skin and thick meat, delicious taste and high nutritional value. Traditional Chinese medicine believes that persimmon has the functions of clearing away heat and moistening dryness, moistening lung and resolving phlegm, quenching thirst and promoting fluid production, and strengthening spleen. In Quanzhou, do you eat persimmons in the first frost? Does the first frost have a runny nose when eating persimmon diced? This statement. Persimmon before frosting is hard, bitter and astringent, and it tastes terrible. The persimmon after frosting is red as fire and tastes sweet and greasy. Pick a peeled persimmon and take a sip of sweet and smooth persimmon juice, which is the delicious taste given by the first frost.