Tea and Common Adulterations

History of tea

Tea is an aromatic beverage made from the dried leaves of the Camellia sinensis plant and is one of the most popular drinks in the world. The history of tea dates back about 5,000 years to ancient China. According to legend, Shen Nong, the Emperor of China, who valued hygiene and nutrition, was boiling water one day when a few leaves from a tea bush accidentally fell into the pot.
The result was a fragrant and delicious beverage that gradually became a medicinal remedy and a widely consumed drink in China. By the 8th century AD, tea had entered Japan. Japanese Buddhist monks who traveled to China for education introduced tea to their country as a means of enhancing focus and relaxation during meditation.
Over time, tea became an integral part of Japanese culture, leading to the development of the Japanese tea ceremony. In the early 17th century, Portuguese and Dutch traders brought tea to Europe. Initially, tea was an expensive and luxurious commodity, consumed only by the upper class. However, by the mid-17th century, tea reached Britain and quickly gained popularity.
To reduce their reliance on tea imports from China, the British began cultivating tea in their colonies, especially in India. By the 19th century, tea had become Britain's national beverage.Tea's introduction to iran, tea was not known in Iran until the 15th century, with coffee being the primary beverage.
During the Safavid era, with the expansion of trade relations with Eastern countries, especially China, tea gradually entered Iran. However, until the mid-Qajar period, it was not widely consumed, and coffee remained the dominant drink. During the Qajar era, Mohammad Mirza Kashef al-Saltaneh, an Iranian diplomat in India, secretly brought tea seeds to Iran. At the time, Britain, which was cultivating tea in India, had banned the export of tea seeds to other countries.
Upon his return, Kashef al-Saltaneh established Iran’s first tea plantations in Lahijan, a city in the Gilan province, earning him the title Father of Iranian Tea. After its introduction to Iran, tea quickly replaced coffee and became an essential part of Iranian hospitality and daily life. Most Iranians prefer to drink tea hot, and consuming hot tea remains a deeply ingrained cultural habit.
 

Tea consumption

Tea is known as the queen of beverages due to its popularity, variety of flavors, and unique preparation methods. It is the second most consumed drink globally after water, with over 5 billion cups of tea consumed daily worldwide.
According to the latest statistics from 2023, annual global tea consumption was approximately 7.3 billion kilograms, with projections indicating an increase to 8.3 billion kilograms by 2029. In Iran, according to global statistics from 2022, the country's annual tea consumption is 150,000 tons, equating to 1.68 kilograms per person per year.
Based on the latest report from the Iranian Tea Organization, Iran imported 42,293 tons of tea in the 12 months of 2023, valued at approximately $229.4 million. The major suppliers were India, Sri Lanka, the UAE, Kenya, Turkey, China, the Netherlands, Vietnam, and Iran’s free trade zones (1,602 tons).
The largest share of imports came from India, totaling 21.339 tons. Despite its popularity, the tea industry faces challenges that can affect its quality and safety. One of the most significant issues is tea adulteration.
 

Tea Adulteration

Tea is one of the most widely consumed beverages globally and is often subject to adulteration. Factors such as climate change (e.g., drought), economic instability, and fluctuating production costs contribute to this issue. Due to the complex supply chain involving multiple producers and distributors, there is a risk of misleading information about tea quality and authenticity.
Key indicators of tea purity and quality include the levels of polyphenols (plant compounds with antioxidant properties that help protect cells from damage) and caffeine. Polyphenols determine both tea quality (higher polyphenol levels indicate better processing and optimal growing conditions) and health benefits (due to their antioxidant and anti-inflammatory properties).
Additionally, polyphenol composition helps identify the geographical origin of tea, as specific polyphenols are unique to certain regions. According to Iran’s National Standard No. 623 (Black Tea - Specifications and Test Methods), the total polyphenol content in black tea must be at least 9% by weight (i.e., in every 100 grams of tea, 9 grams must be polyphenols). Caffeine is another key indicator of tea quality, as premium teas generally contain higher caffeine levels.
It affects the taste balance between bitterness and sweetness and interacts with polyphenols, influencing tea's antioxidant properties. According to Iran’s National Standard No. 623, black tea must contain at least 2% caffeine by weight (meaning that in every 100 grams of tea, at least 2 grams must be caffeine). Tea adulteration poses a significant risk to the quality and safety of this beverage.

Common adulterations in tea

Adulteration in tea is carried out by unscrupulous individuals using various methods, primarily aiming to reduce production costs and increase profit. These practices not only lower the quality of the product but can also pose health risks to consumers. Some common types of tea adulteration include:
 

1. Use of artificial and natural colors

Tea naturally possesses coloring properties due to the presence of polyphenolic compounds that release color when brewed. However, some profiteers add artificial or natural dyes to enhance the appearance and mask the poor quality of tea leaves affected by pests, physical damage, or other defects. These additives are illegal in tea and their use is considered a form of adulteration.
 

2. Adding leaves from other plants to tea

To cut costs or increase product volume, some individuals mix leaves from other plants with tea. A common example is the use of chicory, a cheap additive. Although chicory leaves are visibly different from tea leaves, once they are processed and mixed together, especially in powdered or granulated form, it becomes difficult for consumers to detect the adulteration by visual inspection alone. Such additions can alter the tea's flavor and color, often resulting in an undesirable taste.
 

3. Use of artificial or natural flavors and essences

Selling old or expired tea as fresh tea is another common fraudulent practice in the tea industry. This type of tea typically lacks its original flavor and aroma. To conceal this defect, some vendors add artificial or natural essences to give the product an appealing fragrance and then package it in attractive new containers. This deception helps them win customer trust and increase sales, ultimately boosting illegal profits.
 

Health impacts of adulterated tea

While some types of adulteration may have minimal direct health effects, they are still considered deceptive due to being done without the consumer’s knowledge. However, certain adulterants such as artificial colors and flavoring agents can have serious negative impacts on health over time
. These substances may cause allergic reactions (such as itching, hives, and inflammation), digestive problems, disruptions to the gut microbiome, brain damage, fetal harm during pregnancy, liver and kidney dysfunction, increased risk of cancer, and more.
 

Distinguishing adulterated tea from nonadulterated tea

In addition to buying tea from reputable brands, which is monitored and approved for quality and safety by relevant organizations such as the Standards Organization, the Food and Drug Administration, and so on, you can ensure the quality of the purchased tea by conducting simple tests at home:

1- Pour a few tea leaves into hot water. Nonadulterated tea gradually releases its color, while adulterated tea usually releases color very quickly. Adulterated black tea with artificial coloring releases color very quickly (5 to 6 minutes), creating a dark and unnatural color. Brewing and coloring non adulterated tea takes time, and if brewed for a sufficient time (about 15 to 20 minutes), it creates a natural aroma, flavor, and color (usually reddish-brown).

2- Another way to detect artificial coloring in tea is to pour the brewed tea into a glass and let it sit for 24 hours. After this time, if the tea turns black and settles or if its trace remains after washing the glass, this is a clear sign that the tea contains artificial coloring.