Is it true that people say that drinking iced black tea often will make the skin black?

First of all, talk about the reasons for blackening:

Melanocytes are distributed in the basic cells of human epidermis. Tyrosine contained in melanocytes can oxidize tyrosine into polysaccharides, and then through a series of metabolic processes, melanin can finally be produced. The more melanin is produced, the darker the skin is; On the contrary, the whiter the skin.

Studies have proved that the activity of tyrosine is closely related to elements such as copper, iron and zinc in the body. Often eat things rich in arginine and rare elements such as zinc, copper and iron, such as animal viscera liver and kidney, crustacean clams, crabs, snails, oysters, aquatic products mullet roe, beans such as soybeans, lentils, mung beans and red beans, and hard-shelled fruits such as peanuts, walnuts, black sesame seeds and raisins.

Vitamin C can interrupt the process of melanin production, prevent dopaminefrom further oxidation and reduction to dopa, reduce the content of copper oxide in serum, affect the activity of tyrosine plum, and thus interfere with melanin biosynthesis. If you want clear skin, you may wish to eat more foods rich in vitamin C, such as tomatoes, oranges, lemons, hawthorn, oranges and so on. Vitamin C can reduce the pigmentation of the skin, even remove the dark spots and freckles of the skin, and accelerate the reduction and whitening of the skin; At the same time, it is not advisable to drink too much coffee or too strong coffee, otherwise the skin will turn black easily.

In daily life, if you often eat foods rich in essential substances for melanin metabolism, or constantly supplement foods that can enhance tyrosine activity, your skin color will often be darker. On the contrary, if you regularly eat foods that can interrupt melanin metabolism, your skin will tend to be whiter.

Introduce several foods that can whiten skin:

White radish: Chinese medicine believes that white radish can "benefit the five internal organs, make people white and clean muscles." White radish has this function because it is rich in vitamin C. Vitamin C is an antioxidant, which can inhibit melanin synthesis, prevent fat oxidation and prevent lipofuscin deposition. Therefore, eating white radish often can make the skin white and delicate.

Asparagus: Because asparagus contains high protein and low calories. Whitening doesn't make people fat. Asparagus is also rich in selenium, which can resist aging, prevent and treat various diseases related to excessive oxidation of fat, and make skin white and tender.

Cucumber: Cucumber contains a lot of vitamins and free amino acids, and is also rich in fruit acid, which can clean and whiten skin, eliminate sunburn and freckles, and relieve skin allergies. It is a traditional beauty product.

Bean sprouts: Bean sprouts can prevent freckles and dark spots and make the skin white.

Wax gourd: Wax gourd contains trace elements zinc and magnesium. Zinc can promote human growth and development, and magnesium can make people full of energy, rosy complexion and fair skin.

Tofu: Vitamin B2 in tofu can effectively promote body fat metabolism and moderately moisturize skin. It is an essential nutrition every day.

Chicken breast: rich in collagen. Animal skin and bones are rich in collagen, but it is difficult to take it in. Therefore, chicken breast rich in high-quality protein is worth recommending.

Fish soup: Rich in protein, it can make skin tender and smooth.

Milk and eggs: Rich in protein and vitamins, it can moisturize and whiten the skin. Fitness ladies can choose skim milk, while eggs are only eaten once a day.

Spinach: Spinach not only can supplement iron, but also is rich in vitamin C and vitamin A. The title of top beauty food is well deserved.

Cauliflower: Cauliflower is rich in vitamin C, which can effectively inhibit the production of melanin and prevent the production of black spots and freckles. At the same time, it can also help to produce collagen and bring moisture to the skin.

Lemon: Drinking a glass of lemonade in the morning can not only expel toxic substances from the body, but also have a natural whitening effect, which helps to eliminate freckles.

Vinegar: Add 250 grams of soybeans to vinegar, soak them for 15 days, and eat 10 capsules a day to reduce skin pigmentation.

Sesame: Don't underestimate sesame. It contains protein and vitamin E, which can moisturize the skin and help metabolism.

Millet: It contains a lot of vitamin E and phosphorus, which can promote cell growth and delay cell aging.

Walnut and almond: contain protein, which can promote cell growth and metabolism in the body.

Secondly, let's look at the ingredients of iced black tea:

Water (I don't know what water is, it should be clean anyway)

White sugar (you can buy it all, nothing rare)

Citric acid (citric acid is an important food additive in food processing industry, and is also widely used in medicine, dyes and other industries. There are two production methods of citric acid, one is made from starch and sugar by microbial fermentation; The other is extracted from raw materials with rich acid content, especially in fruit processing, such as the salty juice discharged after making plum embryos, the acid content can reach 4-5%. The salty juice discharged from citrus embryo is a good raw material for extracting citric acid. The process is as follows:

1. Clarification and filtration of raw materials: orange juice and plum juice contain a lot of pectin and impurities, which need to be clarified to promote impurity precipitation, and then filtered by a filter press.

2. Neutralization: calcium carbonate or lime can be used for neutralization, which should be made into slurry in advance, and it is best to add 15% calcium carbonate for neutralization. The specific method is: when the salty and sour water such as orange juice and plum juice is heated to 75 degrees Celsius, calcium carbonate emulsion is gradually added and heating is continued for 2 hours. The initial temperature is controlled at about 5 degrees Celsius, and finally it can rise to 100 degrees Celsius. When the solution is blue-green, it means that the neutralization reaction has been completed. And then standing for precipitation to obtain calcium citrate.

3. Desalination: The obtained calcium citrate contains salt, which can be washed with clean water, heated to 70-80 degrees Celsius, repeated for many times until the salt is completely removed, and dried for later use.

4. Acid decolorization: heating the calcium citrate slurry to 60-70 degrees Celsius, adding 35% sulfuric acid, boiling for about 3 hours, standing for precipitation after the decomposition of calcium citrate is completed, and the supernatant is citric acid solution. Decolorizing dark red citric acid with 1-2% activated carbon for half an hour to obtain a colorless clear solution.

5. Concentrate and crystallize: concentrate the colorless citric acid solution until the solid content reaches 75%, and then let it stand in a crystallization tank for crystallization. Crystallization can be completed in 4-5 days.

6. Centrifugal drying: citric acid crystals still contain certain moisture and impurities, which need to be removed by centrifuge. Then dry at 75℃ until the water content reaches below 65438+/-0%, and finally screen, classify and package to get the finished product).

Black tea powder (name: extracted from tea, selected high-quality black tea such as Dianhong, Qi Hong and Chuanhong as raw materials, and made by scientific and physical extraction.

Actual: pigment+essence+chemical composition = black tea powder)

Salt (eat it every day, I don't need to say it)

Sodium citrate (used as flavoring agent and stabilizer in food and beverage industry; Used as anticoagulant, expectorant and diuretic in pharmaceutical industry; In the detergent industry, it can replace sodium tripolyphosphate as an auxiliary agent of non-toxic detergent; It is also used in brewing, injection, photography and electroplating.

Lemon juice contains a lot of citric acid, which can combine with calcium ions to form soluble complexes, which can reduce the role of calcium ions in promoting blood coagulation and prevent and treat hypertension and myocardial infarction. So it can play an anticoagulant role.

When taking fresh blood in clinic, it is necessary to add some sterilized sodium citrate or sodium oxalate to prevent blood coagulation, so sodium citrate and sodium oxalate are called anticoagulants. )

VC (vitamin c, something serious)

Caramel color (dark brown hygroscopic powder or viscous liquid, bitter and burnt.

Used as colorant for soy sauce, candy, vinegar, beer, etc. , also used in medicine)

Edible essence (food additive, which is a mixture of various edible spices and allowed additives and is used for food seasoning). Additives include carriers, solvents and additives. The carrier includes sucrose, dextrin, gum Arabic, etc. The seasoning creation of edible essence mainly imitates the fragrance and taste of natural fruits and foods, and pays attention to the simulation of fragrance and taste.