Green Tea & Health Benefit of Green Tea
Green tea used to be a "medicine" and could only be taken by upper class people.
In the old day, Green tea was considered a "medicine" because of its high efficacy. And only the aristocrats could drink it.
The functional ingredients of "Green tea", which was once treated as a "medicine", are theanine, which is a glutamic acid derivative and an umami ingredient, and caffeine, which has a bitter taste and stimulates the central nervous system. Tea catechin, a polyphenol, is also famous.
Theanine, an amino acid peculiar to Green Tea that is abundant in Gyokuro and Matcha
Amino acids contained in Japanese Green Tea, theanine accounts for more than half of the total of Japanese Green Tea. Theanine is an ingredient discovered in Gyokuro in 1950. It is said to have been named after the old scientific name of Green Tea plant, "The a sinensis", and is known as an amino acid peculiar to Green tea, which is rarely contained in other plants.
Theanine contained in Green Tea leaves changes to catechin, which is an astringent ingredient when exposed to sunlight. Since Gyokuro and Matcha, which are covered by screen to blocks sunlight for a certain period of time before tea leaves are picked, theanine is abundant in Gyokuro and Matcha.
In Sencha, the first picked tea of the year, which has a shorter exposure period to sunlight, is richer in theanine than the second tea.
The first picked tea of the year is made from "Isshin niyo". The "Isshin ( the core ) " is a leaf in the state of a "bud" which leaves have not opened yet. Because only the core and the two leaves below are picked for making the first picked tea of the year, they are not exposed much ultraviolet rays. There for there is little catechin that is the source of bitterness, and it will be a Green Tea in rich theanine, with a strong sweetness.
Ordinary Green Tea, even the high-class Green Tea, is made by a one core and three leaves. When it comes to mass-produced products, it is made from one-core four-leaf or one-core five-leaf. Only the finest Green Tea and the first picked Green Tea of the year are made by one core and two below leaves. Therefore, tea lovers are looking forward to the first picked Green Tea of the year and making reservations and purchasing around Feb to May ( June in Gyokuro )
Theanine is said to have a function of protecting nerve cells in the brain, and when you take it, it can be expected to have a relaxing effect.
Theanine is also said to have the effect of suppressing the stimulant and arousal effects of caffeine.
Taking theanine and caffeine together, moderates the action of caffeine and has positive effects such as improving memory and work accuracy.
Theanine is also effective in preventing Alzheimer's disease and treating, preventing schizophrenia and depression.
The taste of Japanese tea is composed of four taste elements: astringency, bitterness, umami, and sweetness.
Of the four elements, the ingredient that is said to bring umami and sweetness is the amino acid.
Tea contains many amino acids, but it is said that theanine, glutamic acid, arginine, aspartic acid, glutamine, and serin account for more than 90% of the total.
Of the amino acids contained in tea, theanine actually accounts for more than half.
Theanine is said to have the function of protecting nerve cells in the brain, and when taken, it can be expected to have a relaxing effect.
It is also said to have the following effects.
・ Calms the excitability and arousal effect of caffeine
・ By taking it with caffeine, memory and work accuracy will improve.
・ Prevention of Alzheimer's disease, prevention and treatment of mental illness
Amino acids containing theanine are characterized by being sufficiently extracted even at low temperatures. By brewing tea at low temperature, you can fully enjoy the taste of amino acids.
Japanese Green Tea contains many ingredients, but the one with the highest content is polyphenols. The polyphenol peculiar to Japanese Green Tea is called catechin (tannin) and is attracting attention as an ingredient with various effects.
Polyphenols are pigments found in the leaves and stems of most plants. There are about 5,000 kinds of polyphenols in nature, and it is thought that they have antioxidant effects.
We use the oxygen taken in by breathing to generate energy.
Antioxidant action is the action that prevents cells from being oxidized by active oxygen. Ingesting polyphenols from tea is expected to have the effect of suppressing the action of active oxygen by its antioxidant action and preventing aging, cancer, lifestyle-related diseases, etc.
Catechin is a type of polyphenol contained in tea. In the past, the astringent ingredients were collectively called tannins, but in recent years it has become clear that most of the tannins contained in tea are catechins.
Catechin is an ingredient that brings astringency and bitterness to Japanese Green Tea. There are four main types of catechins contained in Green Tea. The fourth EGCG accounts for about half of all catechins.
・ Epicatechin (EC)
・ Epigallocatechin (EGC)
・ Epicatechin gallate (ECg)
・ Epigallocatechin gallate (EGCg)
Antioxidants are a typical effect of catechins. Antioxidant action is the action of suppressing the action of active oxygen that oxidizes and damages cells.
This action is said to be effective in preventing aging, cancer, lifestyle-related diseases, etc.
In contrast to amino acids, which are extracted even at low temperatures, catechin is a component that is easily extracted at high temperatures. Another feature is that it takes a relatively long time to extract.
Therefore, high temperature extraction is recommended if you want to taste the bitterness and astringency of catechin, and low temperature extraction is recommended if you want to suppress the bitterness and astringency.
Tea catechins are epicatechin and epigallocatechin, and epicatechin gallate and epigallocatechin gallate together contain 10-25% of dry weight, of which EGCG accounts for about half.
EGCG is not found in plants other than tea plants, and its content is significantly reduced in fermented tea. Tea catechin is known as a functional food for those who are concerned about body fat and cholesterol, and it has also been reported that it has an anti-allergic effect.
Caffeine is an ingredient that brings a refreshing bitterness. The following are known health effects.
・ Awakening action (wakes up drowsiness)
・ Diuretic effect (promotes the excretion of waste products and toxins)
・ Vasoconstriction / dilation
Both are good effects depending on how you use them, but overdose may affect your physical condition, so be careful not to overdose. In Japanese Green Tea, theanine is said to have a mild effect on caffeine.
Caffeine is easy to extract at high temperatures, and it takes time to extract at low temperatures. When you want to wake up or concentrate on your work, you can enjoy the crisp bitterness of caffeine by brewing it at a high temperature.
Japanese Green Tea also contains vitamins.
Main ingredients and expected effects
・ Vitamin C: Maintaining healthy skin
・ Vitamin B2: Regeneration of skin and mucous membranes, commonly known as growth vitamin
・ Folic acid: Commonly known as hematopoietic vitamin, a vitamin essential for pregnant women
・ β-carotene: Converts to vitamin A in the body and supports night vision
・ Vitamin E: Strong antioxidant effect, anti-aging
Of the five types of vitamins, the top three are water-soluble vitamins. Since it is easily dissolved in water, it can be extracted well into tea. However, vitamin C and folic acid are sensitive to heat, so brewing at low temperatures is recommended.
On the other hand, the bottom two are called fat-soluble vitamins and have the characteristic of being difficult to dissolve in water. You can hardly extracted Green Tea brewed by hot or cold water. Therefore, it can only be ingested by eating tea leaves. However, the good news is that Matcha is ground high grade Green Tea, so you can get all the nutrients of Green Tea by drinking and eating Matcha.
Japanese Green Tea also contains a total amount of about 5-7% minerals. The main minerals contained in Japanese Green Tea and their expected effects are;
・ Potassium: regulates cell osmotic pressure, maintains nerve and muscle function, and excretes sodium from the body
・ Calcium: Bone and tooth formation, cell division and differentiation, muscle contraction, suppression of nerve excitement
・ Magnesium / Phosphorus: Bone and tooth formation
・ Sodium: Maintaining the function of nerves and muscles
Water-soluble minerals are extracted Green Tea brewed by hot or cold water, but water-insoluble ingredients are not sufficiently extracted. As same as Vitamins, eating whole Green Tea leaves, or take Matcha is an effective way to get water-insoluble minerals of Green Tea.