Coffee Basics Pro

Acids: chlorogenic, quinic, citric, malic, phosphoric

This topic explains the major acids present in green coffee, their roles in flavor and stability, and how they transform during roasting and storage.

Coffee Basics Nerds avatar
  • Coffee Basics Nerds
  • 2 min read
Article 2 of 12 in Green Coffee Chemistry & Aging/
Acids: chlorogenic, quinic, citric, malic, phosphoric

Chlorogenic Acids (CGAs)

  • Content: 6–12% of green Arabica; 10–15% of Robusta.
  • Role: Antioxidants that influence bitterness, astringency, and perceived acidity.
  • Roasting impact: Break down into quinic and caffeic acids, contributing to bitterness and body.

Quinic Acid

  • Origin: Formed during CGA breakdown in roasting.
  • Flavor: Contributes to bitterness and astringency; excessive levels cause harshness.
  • Association: Often linked with darker roasts or aged coffee.

Citric Acid

  • Origin: Naturally present in green beans, especially high-grown Arabicas.
  • Flavor: Bright, citrusy acidity (lemon, orange notes).
  • Roasting impact: Decreases with prolonged roasting.
  • Cup profile: Linked with vibrant, clean acidity in washed coffees.

Malic Acid

  • Origin: Naturally occurring organic acid, especially in coffees from cooler, high-altitude regions.
  • Flavor: Apple, pear, or stone-fruit-like acidity.
  • Roasting impact: Moderately stable but decreases in darker roasts.

Phosphoric Acid

  • Origin: Mineral-derived acid (not fruit-based).
  • Flavor: Tangy, sparkling acidity (often described as cola-like).
  • Cup profile: Common in East African coffees, adds complexity and effervescence.

Role of Acids in Cup Quality

  • Balance: Acids contribute to brightness, complexity, and clarity.
  • Transformation: Lighter roasts preserve more citric, malic, and phosphoric acids; darker roasts emphasize quinic acid bitterness.
  • Varietal/terroir influence: Altitude, soil, and cultivar affect acid composition.

Storage and Aging Effects

  • Prolonged storage reduces organic acids (citric, malic) → dull, flat cup.
  • CGAs and quinic acid remain longer but cause harsher, woody flavors.

Lasting Importance

Acids are the backbone of coffee’s sensory identity. From bright citric and malic notes to the bitterness of quinic acid, their balance and transformation during roasting and aging define whether a coffee tastes lively and complex or flat and harsh.

You might also like:

Comment

Disqus comment here

Coffee Basics Nerds

Written by : Coffee Basics Nerds

Expert coffee historians and brewing enthusiasts dedicated to sharing the rich heritage and techniques behind your perfect cup of coffee.

Recommended for You

Composition: carbohydrates, proteins, lipids

Composition: carbohydrates, proteins, lipids

This topic explains the major chemical components of green coffee—carbohydrates, proteins, and lipids—their roles in green coffee stability, and their transformation during roasting.

Yield vs quality trade-offs

Yield vs quality trade-offs

This topic explains the natural and management-driven trade-offs between maximizing coffee yield and achieving high cup quality, and why farmers, buyers, and consumers must balance these competing priorities.

Cherry anatomy: skin, pulp, mucilage, parchment, silverskin, seed

Cherry anatomy: skin, pulp, mucilage, parchment, silverskin, seed

This topic breaks down the structure of the coffee cherry, layer by layer, showing how each part influences processing, flavor development, and the quality of the final cup.

Flavor and body implications

Flavor and body implications

This topic explains how different honey and pulped natural processes influence the flavor and body of coffee, highlighting the spectrum from clean and bright to sweet and syrupy.