Black tea, known as "red tea" (红茶) in China due to the color of its brewed liquid, is the most oxidized of all tea types. Oxidation is a process that exposes the tea leaves to air, which results in the darkening of the leaves and the development of richer flavors.

Characteristics of Black Tea

• Color: Black tea leaves are dark brown or black. When brewed, the tea generally has a deep amber or dark red color.
• Flavor: Compared to green or white teas, black tea has a stronger, more robust flavor. It can range from malty and sweet to brisk and astringent.
• Caffeine Content: Black tea generally has a higher caffeine content compared to other teas, typically ranging from 40-70mg per 8 oz cup.

Popular Varieties of Black Tea

• Assam: Originates from Assam, India. It has a bold, brisk, and malty flavor and is often used in breakfast blends.
• Darjeeling: From the Darjeeling region of India, it has a delicate aroma and can vary in flavor with the season of harvest. The "first flush" (spring harvest) is often light and floral, while the "second flush" (summer harvest) can be more robust and fruity.
• Ceylon: From Sri Lanka, previously known as Ceylon. It is known for its brisk and bright character.
• Keemun: A high-quality black tea from China with a wine-like and fruity taste.
• Earl Grey: A flavored black tea infused with the oil of bergamot, a type of citrus fruit.

Processing

After being plucked, the leaves are withered to reduce moisture content. They are then rolled to break down the cell walls and release enzymes, initiating the oxidation process. The leaves are spread out and allowed to oxidize, during which they darken and develop flavor. Finally, the oxidized leaves are dried to stop the oxidation process and preserve the tea.

Health Benefits

Black tea contains antioxidants called flavonoids that are believed to have various health benefits, including supporting heart health. It also contains other beneficial compounds like theaflavins and thearubigins. Regular consumption of black tea has been linked to reduced risk of certain chronic diseases, though it's always essential to consult scientific research and health professionals for specific health claims.

Brewing

Typically, black tea is brewed with boiling water and steeped for 3-5 minutes, though the exact time can vary based on personal preference and the specific variety.

In many cultures, black tea is often enjoyed with milk, sugar, or honey, and sometimes with spices, as in the case of Indian chai.

Black tea studies

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Tea (Camellia sinensis) is a plant widely used for ethnopharmacological use due mainly to the presence of polyphenols such as catechin and its derivatives, anthocyanins, flavonoids.

The color varieties are mainly due to differences in treatment, climate, but basically the variations between plants are few.

It is grown in:

• India
• Cina
• Sri Lanka
• Kenya
• Indonesia

The most common are:

• Black Tea: This is the most commonly consumed tea worldwide, especially in Western countries and South Asia. Examples include Assam, Darjeeling, Ceylon, and Earl Grey. Popular ways of consuming it include English breakfast tea and the chai made in India.
• Green Tea: Especially popular in East Asian countries like China and Japan. Examples include Dragonwell, Sencha, Bancha, Matcha, and Gunpowder. Green tea is also becoming increasingly popular in the West due to its purported health benefits.
• Oolong Tea: This is a partially oxidized tea that sits between black and green tea in terms of oxidation. It's especially popular in China and Taiwan. Examples are Tieguanyin and Wuyi Rock teas.
• White Tea: A lightly oxidized tea that retains a delicate flavor and is often described as sweeter than green or black tea. Bai Mudan (White Peony) and Silver Needle are popular varieties.
• Herbal Tea: Although not true teas (since they aren't derived from the Camellia sinensis plant), herbal infusions are widely consumed. Popular examples include chamomile, peppermint, rooibos, and hibiscus.
• Puerh Tea: This is a type of fermented tea from the Yunnan province of China. It comes in raw (Sheng) and ripe (Shou) varieties and is often pressed into cakes.

The characteristic scent of tea seems to be influenced by the jasmonic acid present in the leaves (1).

When tea is taken to prevent or combat disease, attention should be paid to doses and, as with almost all herbs, ingestion of large amounts may be toxic. When the tea is taken for therapeutic purposes for cardiovascular diseases, diabetes and more, the best results are obtained in people who consume 3-4 cups of tea (600-900 mg of catechins) per day (2).

A study from 2004 to 2014 on elderly people found that frequent consumption of tea can reduce the risk of depressive symptoms (3).

Black tea contains important flavonoids which, according to this in vitro study, exerting an inhibitory effect on colon cancer cells could be better studied to become possible medicines (4).

Facial dermatitis is normally treated with calcineurin inhibitors or corticosteroids. Black tea dressings represent an effective treatment option for facial dermatitis (5).

The addition of milk to black tea in some way modifies the impact on blood pressure and vascular function (6).

Theaflavin e thearubigins, two flavonoids isolated from black tea, have been shown to be useful to relieve hyperglycemia and hypercholesterolemia (7).

References____________________________________

(1) Influence of Chloroplast Defects on Formation of Jasmonic Acid and Characteristic Aroma Compounds in Tea (Camellia sinensis) Leaves Exposed to Postharvest Stresses.  Li J, Zeng L, Liao Y, Gu D, Tang J, Yang Z.  Int J Mol Sci. 2019 Feb 27;20(5). pii: E1044. doi: 10.3390/ijms20051044.

(2) Studies on the Prevention of Cancer and Cardiometabolic Diseases by Tea: Issues on Mechanisms, Effective Doses, and Toxicities.  Yang CS, Zhang J. J Agric Food Chem. 2019 May 15;67(19):5446-5456. doi: 10.1021/acs.jafc.8b05242.

(3) Association between tea consumption and depressive symptom among Chinese older adults.  Shen K, Zhang B, Feng Q.  BMC Geriatr. 2019 Sep 4;19(1):246. doi: 10.1186/s12877-019-1259-z.

(4) Inhibitory effect of black tea (Camellia sinensis) theaflavins and thearubigins against HCT 116 colon cancer cells and HT 460 lung cancer cells.  Imran A, Butt MS, Xiao H, Imran M, Rauf A, Mubarak MS, Ramadan MF.  J Food Biochem. 2019 May;43(5):e12822. doi: 10.1111/jfbc.12822.

(5) Black tea dressings - a rapidly effective treatment for facial dermatitis.  Witte M, Krause L, Zillikens D, Shimanovich I.  J Dermatolog Treat. 2019 Jan 22:1-4. doi: 10.1080/09546634.2019.1573306.

(6) Effect of adding milk to black tea on vascular function in healthy men and women: a randomised controlled crossover trial.  Ahmad AF, Rich L, Koch H, Croft KD, Ferruzzi MG, Kay CD, Hodgson JM, Ward NC.  Food Funct. 2018 Dec 13;9(12):6307-6314. doi: 10.1039/c8fo01019f.

(7) Exploring the potential of black tea based flavonoids against hyperlipidemia related disorders.  Imran A, Butt MS, Arshad MS, Arshad MU, Saeed F, Sohaib M, Munir R.  Lipids Health Dis. 2018 Mar 27;17(1):57. doi: 10.1186/s12944-018-0688-6.