Where is Tannic Acid Commonly Found?

January 11, 2026 •

5 min read

Tannic acid is a naturally occurring plant polyphenol found in practically all aerial plant tissues. This compound is responsible for the characteristic astringent, or drying, sensation in many foods and beverages, including strong tea, certain wines, and dark chocolate.

Quick Summary

Tannic acid, a type of plant-derived polyphenol, is present in numerous foods and beverages, notably tea, coffee, wine, chocolate, nuts, and berries. It is known for its distinct bitter and astringent taste and is also used industrially for dyes and leather tanning.

Key Points

Tea: Tannins are a major component in tea, contributing to its color and astringent taste, with concentrations highest in black tea.
Wine: Red wines are rich in tannins from grape skins, seeds, and stems, while oak barrels can also impart tannins during aging.
Fruits and Berries: Berries like cranberries and pomegranates, as well as unripe fruits, are known sources of tannins that add astringency.
Nuts and Cocoa: Walnuts, pecans, and the cocoa used in dark chocolate contain significant tannin levels, which contribute to their bitterness.
Oak and Galls: Historically, bark and insect galls from oak trees have been primary sources for industrial tannic acid used in leather tanning and ink.
Iron Absorption: High tannin intake can inhibit the body's absorption of iron from plant-based foods, which is a concern for people with iron deficiency.
Industrial Use: Beyond consumption, tannic acid has applications in industries ranging from leather tanning to manufacturing inks and rust treatments.

What Exactly is Tannic Acid?

Tannic acid is a specific, commercially available form of tannin, a larger class of polyphenolic compounds. Tannins are found throughout the plant kingdom, serving as a natural defense mechanism against pests and fungi. Their key property is their ability to bind with and precipitate proteins, which is why they create an astringent, drying, and sometimes bitter sensation in the mouth. While the terms 'tannins' and 'tannic acid' are often used interchangeably, tannic acid is a particular type of hydrolyzable tannin with a defined molecular structure. It's widely found in many plants, especially in wood, bark, leaves, and fruits.

Dietary Sources of Tannic Acid

Many of our favorite foods and beverages contain tannic acid or related tannins, which contribute significantly to their flavor, color, and mouthfeel.

Tea

One of the most common dietary sources of tannic acid is tea, derived from the leaves of the Camellia sinensis plant. The concentration of tannins in tea varies depending on the type and preparation method:

Black Tea: As the most fermented type, black tea contains some of the highest concentrations of tannins. The long fermentation process breaks down some compounds, while others, like theaflavins and thearubigins, contribute to its dark color and robust, astringent flavor.
Oolong Tea: Partially fermented, oolong tea has moderate tannin levels, falling between black and green tea.
Green Tea: Made from unfermented leaves, green tea has lower tannin levels but still contains significant amounts of catechins, a type of polyphenol. The longer you steep any tea, the more tannins are released, increasing the astringency.

Wine and Grapes

Tannins are a critical component of wine, particularly red wine, affecting its structure, mouthfeel, and aging potential.

Grapes: The tannins primarily come from the grape's skins, seeds, and stems. Since red wine is fermented with the grape skins for extended periods to extract color, it develops a higher tannin content than white wine.
Oak Barrels: Aging wine in oak barrels also adds tannins, known as enological tannins, which can contribute to the wine's flavor and longevity.

Nuts and Legumes

Nuts and legumes are another significant source of tannins, which often contribute to their bitterness.

Nuts: Acorns are famously high in tannins and need leaching to become palatable. Walnuts, pecans, hazelnuts, and almonds also contain tannins, primarily in their skins and pellicles.
Legumes: Many legumes contain tannins, especially colored varieties like red beans. Peanuts, when shelled, contain very low levels.

Fruits and Berries

Unripe Fruits: Many fruits, like bananas and persimmons, are rich in tannins while unripe. The high tannin content discourages animals from eating the fruit until the seeds are mature. As the fruit ripens, the tannin levels decrease, and the fruit becomes sweeter.
Berries: Cranberries, strawberries, raspberries, and blackberries are well-known for their tannin content, particularly ellagitannins.
Pomegranates: Both the fruit and juice of pomegranates contain high concentrations of tannins.

Other Food and Drink Sources

Chocolate and Cocoa: The astringency of dark chocolate and unsweetened cocoa powder comes from their high tannin content.
Spices: A variety of spices contain tannins, including cinnamon, cloves, cumin, and thyme.
Coffee: Coffee beans contain significant amounts of tannins and other polyphenols, contributing to its flavor profile.

Industrial and Wood-Based Sources

Beyond food, tannic acid has several industrial applications, primarily sourced from wood and galls.

Oak Bark and Galls: Tannic acid is traditionally extracted from the bark and leaves of certain oak trees (Quercus species) and from nutgalls, which are growths on oak twigs caused by insects.
Tanning Leather: The name 'tannin' is derived from its use in tanning animal hides to create leather, a practice that has existed for thousands of years.
Dyes and Inks: Tannic acid is used as a mordant in dyeing textiles and as an ingredient in iron-gall ink, which produces a stable black pigment.
Rust Treatment: It's also utilized in anti-corrosive primers to convert rust into a stable compound, preventing further corrosion of steel.

A Comparison of Common Tannin Sources


Source	Primary Type of Tannin	Key Contribution	Notes on Astringency
Black Tea	Theaflavins, Thearubigins	Color, flavor, antioxidant properties	High astringency, especially when over-steeped
Red Wine	Proanthocyanidins, Ellagitannins	Structure, mouthfeel, aging potential	Astringent, drying sensation felt in the mouth
Oak Wood	Quercitannic acid, Gallotannic acid	Flavoring and aging in wine/spirits	Releases tannins, contributing to color and flavor
Unripe Fruits	Condensed Tannins	Plant defense against pests	Very high astringency, which diminishes with ripening
Dark Chocolate	Proanthocyanidins	Bitter flavor profile	Significant, noticeable bitterness and mouthfeel
Walnuts	Hydrolyzable Tannins (Ellagitannins)	Flavor, antioxidant properties	Astringency particularly concentrated in the skin
Galls (Oak)	Gallotannic acid	Industrial dyes and inks, medicinal uses	Historically significant source for industrial extraction

Health Considerations of Tannic Acid

While tannic acid and other tannins are known for their antioxidant and anti-inflammatory properties, their consumption also has some notable health implications. The most widely recognized is their potential to inhibit iron absorption from plant-based foods. Tannins can bind with iron in the digestive tract, rendering it less available to the body. This is a particular concern for individuals with iron deficiency. To mitigate this, people with low iron levels are often advised to consume tea and coffee between meals rather than with them. For those with sensitive digestive systems, high tannin levels, such as in strong tea, can also cause nausea if consumed on an empty stomach. For a more detailed look at the health benefits of tannins and other polyphenols, a study published in the MDPI journal offers additional insights.

Conclusion

Tannic acid is a ubiquitous plant compound that plays a significant role in our diets and various industries. It is commonly found in everyday items like tea, wine, coffee, and chocolate, where it contributes to the characteristic bitterness and astringency. Rich sources include the skins of grapes and many berries, as well as the shells of nuts. Beyond food, its presence in oak wood and galls has made it invaluable for millennia in leather tanning and ink production. Understanding where tannic acid is found helps explain the sensory experiences associated with these products and highlights the complex interplay between plant chemistry and human use. From the delicate balance in a glass of red wine to the protective compounds in tree bark, tannic acid's presence is widespread and influential.

Frequently Asked Questions

Tannins are a broad category of polyphenolic compounds found in many plants, while tannic acid is a specific, commercially available type of hydrolyzable tannin with a defined molecular structure. The terms are often used interchangeably to describe the astringent taste they produce.

Yes, some processing methods can reduce tannin content. Ripening reduces tannins in fruit, and processes like soaking or boiling can help lower the tannin levels in some legumes and nuts. Steeping tea for a shorter time also minimizes the tannin extraction.

Red wine has higher tannin levels because its production involves extended contact between the fermenting grape juice and the grape skins, seeds, and stems, where tannins are concentrated. White wine is typically fermented without the skins, resulting in less tannin extraction.

Yes, as a polyphenol, tannic acid has antioxidant and anti-inflammatory properties. Research suggests that tannins may help protect cells from damage and offer antimicrobial benefits, although more human research is needed.

Foods with the highest concentrations of tannic acid and related tannins include black tea, red wine, dark chocolate, certain nuts (like walnuts and acorns), unripe fruits, and berries. The specific concentration can vary based on ripeness and processing.

Yes, tannins play a significant role in the color of many products. For example, the dark color of black tea comes from the theaflavins and thearubigins produced during fermentation, which are types of tannins. In aged red wines, tannins form polymeric pigments that stabilize color.

Yes. The tannins in oak barrels are also used to age and flavor spirits like whiskey. Historically, oak tannins were used for other purposes, such as in the leather tanning industry and for creating natural dyes.