Which Alkaloids Are in Coffee? A Complete Guide to the Compounds in Your Cup

January 3, 2026 •

3 min read

With over 2.25 billion cups consumed globally every day, many know that caffeine is the source of coffee's stimulating kick. However, the stimulating properties and complex flavors of the beverage are attributed to a cocktail of active compounds, leading many to ask: which alkaloids are in coffee besides the most famous one?.

Quick Summary

Coffee contains several alkaloids, including the major compounds caffeine and trigonelline, alongside trace amounts of theobromine and theophylline, influencing its flavor and effects.

Key Points

Caffeine is a Stable Xanthine: The most well-known coffee alkaloid, caffeine, is a central nervous system stimulant that withstands the high temperatures of the roasting process.
Trigonelline is a Flavor Precursor: This heat-sensitive pyridine alkaloid degrades during roasting, creating key aroma compounds and producing nicotinic acid (Vitamin B3).
Roasting Affects Alkaloid Balance: Lighter roasts retain more trigonelline, while darker roasts have less. The caffeine content, however, remains largely constant across roast levels.
Theobromine and Theophylline are Minor: These purine alkaloids are present in trace amounts in coffee beans, mostly serving as metabolic precursors to caffeine within the plant.
Human Metabolism Creates More Alkaloids: After consumption, the body metabolizes some of the caffeine into theobromine and theophylline, adding to the total alkaloid effect.
Cold Brew Preserves Trigonelline: Due to the absence of heat, cold brewing methods extract more of the thermolabile trigonelline, affecting the final brew's chemical composition.

The Primary Coffee Alkaloids: Caffeine and Trigonelline

Alkaloids are a group of naturally occurring chemical compounds that contain mostly basic nitrogen atoms. In coffee, these compounds are responsible for the well-known stimulating effects and many of the beverage's distinctive flavor characteristics. While many associate coffee's buzz with a single compound, the reality is a bit more complex. The coffee plant, particularly in its green bean state, produces two main types of alkaloids: the purine alkaloid caffeine and the pyridine alkaloid trigonelline.

Caffeine: The Most Famous Stimulant

Caffeine (1,3,7-trimethylxanthine) is arguably the most recognized alkaloid in coffee and is found in the beans, leaves, and fruits of the Coffea plant. As a powerful central nervous system stimulant, it's the compound most people seek for increased alertness and energy. The concentration of caffeine varies significantly depending on the coffee species. For instance, Robusta coffee beans contain considerably more caffeine (around 2% of dry weight) than Arabica beans (typically up to 1% of dry weight). Unlike other alkaloids in coffee, caffeine is remarkably heat-stable, meaning the roasting process does not significantly reduce its content.

Trigonelline: The Flavor Precursor

Trigonelline (N-methylnicotinic acid) is the second most abundant alkaloid in green coffee beans, sometimes found in concentrations higher than caffeine. In its raw form, trigonelline contributes to coffee's bitter flavor. Its defining characteristic, however, is its thermolability, meaning it's highly sensitive to heat. During the roasting process, temperatures exceeding 160°C cause trigonelline to degrade. This thermal degradation is crucial for coffee's profile, as it produces several key aroma compounds and, most notably, nicotinic acid (niacin, or Vitamin B3). Some research also suggests potential neuroprotective and cognitive benefits associated with trigonelline.

Minor and Metabolized Alkaloids

While caffeine and trigonelline dominate the alkaloid profile, coffee also contains trace amounts of related compounds. Theobromine and theophylline are two such alkaloids, also belonging to the xanthine family like caffeine. These are actually precursors in the caffeine biosynthesis pathway within the coffee plant. The plant's efficient conversion process leaves very little of these compounds in the finished bean. However, once consumed, the human liver metabolizes a portion of the ingested caffeine into theobromine, theophylline, and paraxanthine.

The Effect of Roasting and Brewing on Coffee Alkaloids

The heat applied during roasting is the most significant factor affecting the final alkaloid content of a coffee brew. The different chemical properties of caffeine and trigonelline cause them to behave very differently under heat.

Roasting's impact on alkaloids:

Caffeine: The caffeine content remains largely unchanged, so a darker roast will not make the coffee less caffeinated.
Trigonelline: Over half of the trigonelline content is lost during roasting, producing flavor compounds and nicotinic acid. Darker roasts will therefore have lower trigonelline levels than lighter roasts.

Brewing methods can also influence the final alkaloid concentration. Studies have shown that cold-brew coffee contains noticeably higher levels of trigonelline than hot-brew coffee, as the lower temperatures prevent its thermal degradation. Extraction time is also a factor, as seen in espresso preparation, where longer extraction can result in lower trigonelline content.

A Comparison of Coffee Alkaloids


Feature	Caffeine	Trigonelline	Theobromine / Theophylline
Classification	Purine Alkaloid (Xanthine)	Pyridine Alkaloid	Purine Alkaloids (Xanthine)
Primary Function in Humans	Central Nervous System Stimulant	Flavor, potentially cognitive benefits	Mild stimulants, vasodilator, diuretic
Stability during Roasting	High (remains stable)	Low (decomposes rapidly)	Very low (precursors to caffeine)
Concentration in Green Beans	Up to 4% (Robusta)	Up to 2%	Trace amounts
Source in Coffee Brew	Direct extraction from beans	Partially degraded during roasting	Human metabolism of caffeine

Conclusion

While caffeine is undoubtedly the star player among coffee's alkaloids, it's just one part of a complex cast of compounds. Trigonelline, with its role in shaping flavor and its intriguing health benefits, is a major contributor to coffee's overall character, especially in lighter roasts. Trace amounts of theobromine and theophylline, though minor in the bean itself, appear after consumption as products of caffeine metabolism. The interplay of these various alkaloids, influenced by factors like bean origin, roasting, and brewing, is what makes every cup a unique sensory and physiological experience.

Learn more about the metabolism of coffee alkaloids in this review: Metabolism of alkaloids in coffee plants.

Frequently Asked Questions

While caffeine is the most famous, trigonelline is sometimes found in higher concentrations in green (unroasted) coffee beans. However, much of the trigonelline degrades during the roasting process.

Yes, decaf coffee is not completely free of alkaloids. It undergoes a process to remove most of the caffeine (typically 97% or more), but trace amounts of caffeine remain, along with other alkaloids like trigonelline.

Roasting has a major effect on trigonelline, causing it to break down into flavor compounds and nicotinic acid. The caffeine content, however, remains quite stable during roasting.

Contrary to a common myth, the caffeine content is not significantly reduced by roasting. Therefore, the difference in caffeine between light and dark roasts is minimal, though it can vary slightly due to the physical changes of the bean.

These compounds are precursors in the plant's metabolic pathway for creating caffeine, so only trace amounts are typically present in the final coffee bean.

While it contributes bitterness in its raw form, the breakdown of trigonelline during roasting is vital for developing the sweet, caramel, and earthy aromas associated with roasted coffee.

The alkaloids in coffee, primarily caffeine, act as stimulants that can increase alertness, raise heart rate, and temporarily increase blood pressure. Theobromine has a milder stimulating and diuretic effect, while trigonelline shows potential neuroprotective benefits.

No, alkaloids are a large class of organic compounds found widely throughout the plant kingdom. Caffeine is also found in tea and cocoa, while trigonelline is found in many plants, including fenugreek.