TLDR

A cup of black coffee (about 240 mL or 8 oz) contains a small but notable amount of amino acids, primarily from the proteins in coffee beans. Here’s an estimated breakdown of its amino acid profile per cup:

Amino Acid Content in Black Coffee (Approximate Values)
Amino Acid Amount (mg per cup)
Alanine ~1–5 mg
Arginine ~1–5 mg
Aspartic Acid ~5–15 mg
Cysteine ~0.5–2 mg
Glutamic Acid ~10–30 mg
Glycine ~1–5 mg
Histidine ~1–3 mg
Isoleucine ~1–3 mg
Leucine ~2–5 mg
Lysine ~1–3 mg
Methionine ~0.5–2 mg
Phenylalanine ~2–6 mg
Proline ~2–7 mg
Serine ~2–6 mg
Threonine ~2–5 mg
Tryptophan ~0.5–2 mg
Tyrosine ~1–4 mg
Valine ~2–5 mg
Key Points:
Coffee is not a significant source of protein but contains trace amounts of free amino acids.
The highest concentrations are in glutamic acid, aspartic acid, and proline.
These amino acids contribute to coffee’s umami, bitter, and slightly sweet flavors.

1. Water (~98%)
The majority of coffee is just water, which helps extract and dissolve the compounds from coffee beans during brewing.
2. Caffeine (~80–120 mg per cup, depending on brew strength)
A natural stimulant that enhances alertness by blocking adenosine receptors in the brain.
May boost metabolism, improve mood, and enhance athletic performance.
3. Organic Acids (pH ~4.5–5.0, giving coffee its acidity)
Acid Effects & Taste
Chlorogenic acids Antioxidants; contribute to bitterness & slight astringency
Quinic acid Adds sourness/astringency; increases as coffee cools
Citric acid Bright, fruity acidity (common in Arabica beans)
Malic acid Found in some high-altitude coffees; gives an apple-like tartness
Acetic acid Vinegar-like, contributes to sharp acidity
Phosphoric acid Mild sweetness, found in some African coffees
4. Lipids (Coffee Oils)
Mainly cafestol & kahweol (found in unfiltered coffee like French press).
Can increase cholesterol levels slightly but have potential anti-inflammatory benefits.
Mostly present in espresso and unfiltered coffee, but much lower in filtered coffee.
5. Polyphenols & Antioxidants
Coffee is rich in antioxidants, which may help reduce oxidative stress.
Notable polyphenols:
Chlorogenic acids – contribute to health benefits but also to bitterness.
Melanoidins – formed during roasting, responsible for coffee’s dark color & aroma.
6. Minerals (Trace Amounts)
Mineral Amount per Cup Function
Potassium 80–120 mg Electrolyte balance, heart function
Magnesium 5–10 mg Muscle & nerve function
Calcium 2–5 mg Bone health
Sodium <5 mg Nerve & muscle function
Phosphorus 5–10 mg Energy metabolism
7. Sugars & Carbohydrates (Minimal)
Coffee contains tiny amounts of carbohydrates, mostly in the form of mannose, arabinose, and galactose.
Some of these sugars break down during roasting, contributing to the sweetness & caramel-like flavors.
8. Amino Acids (Trace Amounts)
See previous breakdown.
9. Volatile Compounds (Aromas & Flavors)
Coffee’s smell and taste come from over 800 volatile compounds, including:
Furans (caramel, roasted notes)
Pyrazines (nutty, earthy flavors)
Aldehydes (sweet, floral notes)
Phenols (smoky, clove-like)
What’s Not in Black Coffee?
No sugars (unless added)
No fat (except in unfiltered coffee with natural oils)
No protein in significant amounts