Theanine is an amino acid that is only contained in tea, and the content of theanine in tea is the highest. L-theanine is synthesized in the roots of tea trees, transferred to the leaves through the branches, accumulates in the leaves, and the theanine is converted into catechin by sunlight. Therefore, L-theanine is in the high-grade green tea cultivated by light. The content is higher, but the content in the coarse tea leaves is less, and the content of polyphenols is increased.

First, the physiological role of L-theanine

It is well known that theanine has the effect of inhibiting caffeine and improving the flavor of tea soup, but in recent years, it has been found that its more important physiological effect is the effect on the changes of the nerves in the brain and the effect of lowering blood pressure.

(1) Changes in the nerves in the brain

It has been reported that L-theanine is fed to the rat to be absorbed from the intestine and transported by the blood into the liver and brain. The brain has a special regulatory mechanism that allows only certain substances to pass through, while L-theanine can be absorbed into the brain through the L-system delivery system. The study found that L-theanine was absorbed into the brain and the amount of dopamine in the brain was significantly increased by the influence on brainline conditions. Dopamine is a precursor of norepinephrine and plays an important role in the transmission of excitation of brain nerve cells. L-theanine is very important for the performance of dopamine.

(2) the role of lowering blood pressure

The L-theanine dissolved in physiological saline was administered to the hypertensive rats by intraperitoneal administration, and the blood pressure changes one hour before and after the administration were measured. It was found that the blood pressure was decreased to a certain extent according to the amount of administration, and the large amount of administration was significantly lowered. Moreover, there is no blood pressure drop in the normal blood pressure of the rats, indicating that L-theanine only has a blood pressure lowering effect on the rats with hypertension.

(3) sedative effect

Everyone knows that tea contains excitatory caffeine, but when people drink tea, they feel relaxed, quiet, comfortable, and the atmosphere is calm, which makes the excited mood calm. It has been confirmed that this is mainly the action of L-theanine.

The physiological method of measuring "sedation" is 1 JL, and the rational method is brain wave measurement. According to the difference of the head current frequency, the brain wave can be divided into 8 waves, 9 waves, p waves, 8 waves appear when sleeping, 9 waves appear when playing tons, o waves appear when quiet, p waves are excited. The sedative effect of L-theanine passes through the brain waves. The measurement of the wave has been confirmed. The brain wave measurement was carried out in a sealed environment at room temperature of 25 ° C and light exposure of 40 Lux. The subjects were given water (100 ml) and 50 mg/100 ml, 200 mg/100 ml of the theanine aqueous solution, and the brain wave was measured after 60 minutes. The results showed that the a-wave of the test group with the aqueous solution of theanine was significantly increased compared with the control group of the drinking water.

Sedative effect on different degrees of uneasiness

In order to study the effects of L-theanine in mental states with different degrees of restlessness, the brains of 50 female students were used to measure the brains of highly uneasy and low-degree unconscious people. Wave changes. The results showed that before the consumption of theanine. When the wave appearance was 1, the low-degree anxiety group reached 1.0 times after taking 50 mg, and 1.03 times after taking 200 mg; and the high-distance group took 50 mg and 200 mg. The wave appears to be more than 2 times the maximum, with an average of 1.2 times.

Second, the application in food

(1) Sedative effect when added to food

L-theanine is easily soluble in water and can be widely used in foods such as beverages, baked snacks, and frozen snacks. For example: concentrated extract of black tea (Bx = 20) 5%, stuffing sugar (Bx = 7.5) 5%, sugar 15%, gel 1%, L-theanine 0.2%, citric acid 0.2%, sodium citrate 0.2%, add water to make 100% black tea jelly. After 60 minutes of consumption, the brain wave was measured and measured once every 5 minutes, and it was found that after eating. The amount of wave immediately increased, and it increased significantly after 30 minutes, up to 1.6 times. The study also confirmed that the addition of candy, various beverages, etc. can achieve a good calming effect.

(2) I-theanine flavor improvement effect

L-theanine can be used as a green tea flavor improver, and it can also suppress bitterness and spicy taste in other foods, and achieve the purpose of improving food flavor.

Cocoa drinks and wheat tea have unique bitterness or spicy taste. Adding sweeteners will have an unpleasant taste. If 0.01% L-theanine is used instead of sweetener, the result shows that L-theanine is added. The flavor of the drink is greatly improved. Studies have also confirmed that in other foods, such as coffee, cocoa, ginseng drinks, beer, etc., there is a good effect of improving the flavor. It shows that L-theanine has broad application prospects in the food industry.