Coffee

Coffee does not simply grow in the supermarket – it comes from plants cultivated in warm regions of the world. The two most important coffee species are Arabica and Robusta. Arabica is like the “finer” coffee: it often has a milder and more aromatic taste. Robusta is stronger and contains more caffeine, so it has a more awakening effect and is sometimes used in espresso blends because it produces a thicker crema. You can roughly imagine it like two apple varieties: one is sweeter and more delicate, the other somewhat stronger and tarter.

Origin and growing regions
Coffee is mainly grown in a belt around the equator, often called the “coffee zone”. Important producing countries include:

In these countries the mountains, warmth and rainy seasons create conditions in which coffee plants grow well. You can imagine coffee there as a sensitive plant that needs certain “living conditions” – not too hot, not too cold, enough water, and usually some shade.

Available forms and variants
In the shop you find coffee in many different forms. Here are some simple explanations:

Special terms explained simply
Sometimes you read words like „Single Origin“ or „Blend“. Single Origin means the coffee comes from a specific country or even a specific farm – like a juice made from a single apple variety. Blend is a mixture of different coffees designed to create a consistent flavour, similar to a mixed fruit salad that always tastes the same.

Many shops also offer organic coffee (grown without certain pesticides) or Fairtrade coffee (where farmers are supposed to be paid fairly). This increases choice and these variants are sometimes a bit more expensive. Overall, coffee is available almost everywhere – in supermarkets, specialist shops, online or in cafés. That way anyone can easily find the form and taste they prefer.

Coffee refers both to the beans of plants of the genus Coffea and to the beverage made from them. The economically most important species are Coffea arabica (Arabica) and Coffea canephora (Robusta). Arabica beans are characterized by a more complex aroma and lower caffeine content, while Robusta provides harsher, earthier flavours and a higher caffeine content. Coffee is cultivated worldwide and has high economic importance in tropical and subtropical regions.

Botany and harvest
The coffee plant is an evergreen shrub or small tree that produces red to yellow drupes (cherries). Ripe cherries are either selectively hand-picked or mechanically harvested by the strip-harvest method. After harvest comes processing, in which two main methods are distinguished: the wet (washed) and the dry (natural) process. In the wet process the fruit flesh is removed and the beans are fermented and washed; the result is often a cleaner, finer flavour structure. In the dry process the cherries are dried in the sun, which preserves fruit and sweetness notes more strongly.

Chemical composition
Green coffee contains over 1000 known chemical compounds. The most important include:

Roasting and physical changes
Roasting is a thermal process in which green beans are chemically and physically altered at temperatures between about 180–240 °C. During roasting Maillard reactions, caramelization and pyrolysis occur. Beans lose water, more voluminous pores and gases (including CO2) form, and weight decreases. Light roasts preserve more acidity and original aroma components; dark roasts produce stronger roasted and bitter flavours, less acidity and higher concentrations of melanoidins.

Nutritional values
Black coffee contains almost no calories, typically 1–5 kcal per 100 ml, virtually no fats or carbohydrates and small amounts of minerals such as potassium, magnesium and niacin. Added ingredients like milk, sugar or syrups significantly increase energy content and nutritional values.

Health aspects
Due to caffeine, coffee provides a short-term increase in alertness and attention by blocking central adenosine receptors. Epidemiological studies show associations between moderate coffee consumption (typically 3–4 cups/day) and a reduced risk of type 2 diabetes, Parkinson’s disease, certain liver conditions and overall mortality, although causality is not always clear. Negative effects arise with very high consumption, e.g. sleep disturbances, increased heart rate or anxiety, especially in caffeine-sensitive individuals. An approximate guideline for maximum daily caffeine intake for healthy adults is about 400 mg.

Safety and quality factors
Contamination with mould toxins (e.g. aflatoxins), pesticides or unwanted residues can occur and are minimised by proper drying, storage and control. Sensory quality assessment is carried out by cupping tests that evaluate aroma, acidity, body, aftertaste and defects.

Summary
Coffee is a complex natural product with a variety of chemical components whose interplay, influenced by variety, cultivation, processing, roasting and preparation, determines the final flavour profile and health effects. Scientific research continually provides new insights into constituents, health effects and processing optimisations, so coffee remains both culturally and chemically fascinating.