The source of bitter taste of spring bamboo shoots is complex, which is not only related to the genes of the varieties themselves, but also changes with the changes of soil environment, climate temperature, sunlight intensity and post-harvest treatment methods, among which the intensity and time of sunlight irradiation have a direct impact on the bitter taste of spring bamboo shoots.

Spring bamboo shoots, as the name implies, grow in spring. There are many varieties, the big ones weigh nearly ten kilograms, and the small ones are only as thick as little fingers. Spring bamboo shoots are the bud embryos of bamboo, and each spring bamboo shoot is a strong bamboo when it grows up, so it is called bamboo embryo, bamboo bud and bamboo sprout.

I have to talk about winter bamboo shoots here. Many people mistakenly think that winter bamboo shoots are also bamboo when they grow up. In fact, winter bamboo shoots are just swellings on the nodes of bamboo whips. If they are not dug up, they will only die in the ground and will not grow into bamboo.

Although bamboo shoots are delicious, fresh bamboo shoots have a fly in the ointment and often taste bitter. Let's find out what substance caused the bitter taste of bamboo shoots first.

-substances that cause the bitter taste of bamboo shoots

The main substances that cause the bitter taste of bamboo shoots are tannins and amino acids, followed by oxalic acid. The existence of these three substances in bamboo shoots is not static, and there are great differences due to the changes of bamboo shoot growth environment, and the content distribution of these three substances is different in different varieties and different parts.

tannin

Tannin is a mixture of various phenolic derivatives, which naturally exists in bamboo shoots. The content of tannin is one of the important indexes that affect the astringency of bamboo shoots. We all know that tannins are often mentioned in wine. In the field of wine, tannins are a contradictory whole. High-quality wine can not be separated from heavy tannins, and tannins will also bring bitter taste to wine. Walnut is also a nut with high tannin content, so we will feel obvious astringency when eating it.

Tannins are mostly distributed in parenchyma cells of bamboo shoots, and a little in fiber cells. Different varieties of bamboo shoots have great differences in tannin content. Experimental data show that the tannin content of bamboo shoots is high, with an average of 0.37%. The tannin content of bamboo shoots in Xiao Ye is often only half that of bamboo shoots, and the tannin content of bamboo shoots in winter is lower than that of bamboo shoots, with an average of 0.15%. This is one of the reasons why we usually think that spring bamboo shoots are more bitter than winter bamboo shoots.

amino acid

Bamboo shoots are rich in amino acids, with a total content of10.23g/kg. * * There are 18 kinds, among which 8 kinds of amino acids are essential for human body, namely valine, lysine, threonine, phenylalanine, leucine, methionine, isoleucine and tryptophan. Among these eight amino acids, some are bitter amino acids, others are sweet amino acids, and different amino acids bring different tastes.

Amino acids will also vary greatly depending on the variety and growth environment of bamboo shoots. Taking three kinds of bamboo shoots, namely, Dendrocalamus latiflorus, Phyllostachys pubescens and Phyllostachys pubescens, as examples, the contents of essential amino acids in these three kinds of bamboo shoots are generally high, accounting for 29.02-35.95% of the total amino acids, while the amino acids in Phyllostachys pubescens are relatively low in these three kinds of bamboo shoots. In addition, soil, temperature, light and other factors have great influence on the bitter amino acid content of bamboo shoots.

oxalic acid

Although oxalic acid has a certain influence on the bitter taste of bamboo shoots, it is not the biggest source. Many articles about the bitterness of bamboo shoots on the Internet attribute all their bitterness to oxalic acid, which is biased. The organic acid in bamboo shoots is mainly oxalic acid, and the content of oxalic acid in fresh bamboo shoots varies from 15.7 mg to 46.2 mg per kilogram. Among vegetables, spinach is the most typical one. The content of oxalic acid in spinach leaves is about 82. 1 mg per kilogram, which is much higher than that in bamboo shoots. However, when we usually eat spinach, we never feel obvious bitterness, so the oxalic acid in bamboo shoots only plays a supporting role in bitterness.

-methods to remove the bitter taste of spring bamboo shoots

(1) blanching

Blanching bamboo shoots to remove bitterness is the most common treatment method. With high temperature boiling, tannin, bitter amino acid and oxalic acid are decomposed and volatilized. Specific operation: peel off the shell of bamboo shoots, cut off the old and hard parts of bamboo shoots, slice large bamboo shoots (small bamboo shoots don't need to be cut), put them in boiling water with a small amount of salt, take them out and drain them before cooking. The blanching time should not exceed 10 minute, otherwise the bamboo shoots or strips will lose their original delicious brittleness.

Advantages and disadvantages of this method:

Advantages: the effect is obvious, and the bitterness is reduced by more than 80%. Disadvantages: while removing bitter amino acids, sweet amino acids and other nutrients are lost at the same time.

② soaking

Soaking can also decompose and volatilize tannins, bitter amino acids and other substances that make bamboo shoots bitter. The soaking method is very simple. The specific operation is: peel off the shell of the bamboo shoots, wash them, cut off the old and hard parts of the bamboo shoots, and then cut them in half vertically and put them into the pot. Boil the rice washing water, pour it directly into the pot, and soak it for1~ 2 days with the cover. The longer the soaking time, the less bitter taste, preferably not more than 2 days, especially in high temperature weather, it is easy to turn sour and soft.

Advantages: convenient operation and unique fragrance. Disadvantages: it takes a long time and is restricted by the temperature.

③ Cooking

Cooking at high temperature is the same as boiling to remove bitterness and astringency, so I won't explain it here. Cooking method is more suitable for small bamboo shoots, and it can still keep the brittleness of small bamboo shoots. Specific operation: peel off the shell of small bamboo shoots, wash them, cut off the hard base, cut them into small bamboo shoots, add vegetable oil, soy sauce, chopped pepper, lobster sauce and salt, mix them evenly, put them in an electric pressure cooker, and then take off the cooking button and drop the valve.

Advantages: the bitter taste disappears, the finished product is completed at one time, simple and convenient, and the brittleness is still good, and the original flavor and nutritional components of the spring bamboo shoots are retained to the maximum extent. Disadvantages: it is only suitable for small bamboo shoots, and the variety of bamboo shoots is limited. In addition, for heavy-flavored ones, the taste is too light.

④ Optimum freshness

Spring bamboo shoots will taste more delicious as soon as they are dug out. As time goes on, they will not only get old, but also increase tannins, bitter amino acids and other substances, and the bitter taste will increase.

-Little-known secret of bamboo shoots

Effect of light intensity on bitter taste of bamboo shoots

The time and intensity of sunlight directly affect the bitter taste of bamboo shoots. During the growth of bamboo shoots, the longer the sunlight exposure time, the greater the intensity of the exposure, the higher the contents of tannins, bitter amino acids and oxalic acid, and the heavier the bitter taste of bamboo shoots, so the bamboo shoots facing the sun are less bitter than those facing the sun. Under the same light intensity, bitter amino acids decreased from the shoot tip to the damaged base, and with the decrease of light intensity, the content of sweet amino acids increased in different degrees. ?

In order to improve the quality of bamboo shoots and reduce their bitter taste, experienced farmers will cover them with soil or pull sunshade nets and bag them to artificially create a dark environment and reduce the bitter taste of bamboo shoots. ?

This is the reason why winter bamboo shoots are sweeter than spring bamboo shoots, because winter bamboo shoots have no light.

Different bamboo shoots have different bitter and astringent tastes.

The content of bitter substances in different nodes of bamboo shoots is quite different. The bitter taste of bamboo shoots is mainly concentrated in the tip of bamboo shoots, and the bitter taste gradually decreases as it goes down. There is little or no bitter taste at the base of bamboo shoots. Taking green bamboo shoots as an example, the content of bitter amino acids in the shoot tip is 2.6 times that of the shoot base, and the cyanide in the shoot tip is 36.38 times that of the shoot base. It can be seen that the tip of bamboo shoots is the most bitter, followed by the middle, and the base of bamboo shoots is almost bitter when buried in the ground.