Coffee (Coffea spp.)

Description

Coffee is the product obtained from the mature seeds of plants belonging to the genus Coffea, in the botanical family Rubiaceae. Native to eastern Africa, it is now cultivated in more than seventy countries along the tropical “coffee belt”. The most economically relevant species are Coffea arabica, known for its refined aroma, smoother taste and greater sensory complexity, and Coffea canephora (robusta), appreciated for its higher caffeine content, stronger body and superior agronomic resistance.

The fruit, commonly known as a cherry, usually contains two seeds. These seeds are initially green, hard and lacking any characteristic coffee aroma. Their sensory profile develops during roasting, a thermal process in which reactions such as the Maillard reaction, the breakdown of carbohydrates and proteins, and the transformation of chlorogenic acids produce hundreds of volatile compounds responsible for aroma and flavor.

The finished product consists of brown roasted beans, darker or lighter depending on the roasting profile. Once ground, coffee is extracted with hot water using different methods such as espresso, moka, filter brewing, percolation or cold brew, each highlighting distinct sensory elements like acidity, bitterness, crema, body and caffeine extraction.

Beyond being one of the most consumed beverages worldwide, coffee is a chemically complex ingredient rich in alkaloids, polyphenols, trigonelline, and lipids such as cafestol and kahweol. Sensory quality is influenced by botanical variety, altitude, post-harvest processing (washed, natural), roasting profile and freshness, making coffee one of the most expressive and variable agricultural products, with broad applications in food, beverages and cosmetics.

Some climatic factors are of great importance for the cultivation of coffee and are:

Temperature that must be between 23 ° and 28 °
Rain that must fall within the parameters between 1500 and 2000 mm.
The species are basically two:

• Arabica (Coffea arabica) cultivated in South America. 60% of world production.
• Robusta (Coffea canephora) cultivated in Africa.

Botanical classification

• Common name: coffee (coffee tree, coffee cherry, coffee bean)

• Main botanical names:

  • Coffea arabica (Arabica coffee)

  • Coffea canephora (Robusta coffee, incl. Conilon/Nganda)

• Family: Rubiaceae

• Origin: Tropical Africa (in particular Ethiopia and Central Africa) and Madagascar; now cultivated across the tropical belt in Latin America, Africa and Asia

Cultivation and growing conditions

Climate

• Typical tropical perennial crop, needing mild temperatures and relatively high air humidity.

• Arabica usually prefers 15–24 °C and is often grown at medium–high elevations, where cooler conditions slow fruit development and enhance aromatic quality.

• Robusta tolerates higher temperatures (roughly 24–30 °C) and is grown at lower altitudes in hotter, more humid areas.

• Coffee requires substantial rainfall, often between about 1,200 and 2,000 mm per year, ideally with a marked but not extreme dry period to induce flowering.

• Does not tolerate frost: even brief exposure to temperatures near 0 °C can seriously damage plants.

Exposure

• In many traditional systems, Arabica is grown under partial shade (shade-grown coffee) beneath taller trees, which moderate light intensity, wind and temperature fluctuations.

• In other systems, especially for Robusta, coffee can be grown in more open, sunnier plantations, provided soil moisture and irrigation are well managed.

• Excessively strong direct radiation combined with drought can cause leaf burn, stress and reduced yields.

Soil

• Prefers deep, well-drained, slightly acidic soils with good organic matter content.

• Loam to sandy-loam or loam-silt textures are generally favourable, provided structure is good and no compact layers impede root penetration.

• Prolonged waterlogging must be avoided, as it leads to root rot and decline.

• Sloping land is common in coffee regions; where slopes are significant, soil conservation measures (terraces, contour planting, cover crops) are essential.

Irrigation

• In regions with regular rainfall, coffee may be grown without irrigation.

• Where rainfall is irregular or insufficient, supplementary irrigation is important to maintain yield and bean quality.

• A short, controlled dry period followed by rainfall or irrigation often triggers flowering.

• During fruit development and ripening, prolonged water stress should be avoided to prevent reduced fruit size, defects and premature drop.

Temperature

• Best performance occurs within a relatively narrow mild temperature range, avoiding extremes.

• Persistent temperatures above about 30–32 °C, especially with intense radiation and low humidity, can reduce fruit set and negatively affect bean quality.

• Low temperatures slow growth and increase susceptibility to cold damage, particularly in young trees or in exposed, windy sites.

Fertilization

• Coffee is a nutrient-demanding perennial, especially in intensive plantations.

• Requires adequate nitrogen to support vegetative growth and continuous cropping, as well as phosphorus and potassium for root development, flowering, fruit set and bean quality.

• Organic amendments (well-matured manure, compost, mulches) help maintain soil structure, biological activity and long-term fertility.

• Fertilization plans are ideally based on periodic soil tests and, when available, leaf analysis; micronutrients (e.g. boron) are important for flowering and fruit setting.

Crop care

• Pruning is crucial to:

  • control tree height,

  • renew fruiting wood,

  • maintain an open, well-ventilated canopy.

• Weed control is achieved through hoeing, mulching or managed ground covers between rows.

• Monitoring of pests and diseases (e.g. coffee leaf rust, coffee berry borer, leaf miners, scales) is essential, with preference for integrated pest management approaches.

• Agroforestry systems (shade trees, intercropping) are often used to improve microclimate, biodiversity and overall system resilience.

Harvest

• Coffee cherries (drupes) usually ripen in waves; harvest can be:

  • selective picking by hand, choosing only fully red, ripe cherries (typical in high-quality Arabica production),

  • strip picking or mechanical harvesting, where all cherries on a branch are harvested at once.

• Harvesting cherries at the correct ripeness is fundamental for final cup quality.

• After harvest, cherries undergo processing (washed, natural, honey or other methods), followed by drying and hulling to obtain green coffee beans.

Propagation

• Propagation is mainly from seed, producing seedlings in nurseries, which are later transplanted to the field.

• For elite material or specific cultivars, vegetative techniques (cuttings, grafting, micropropagation) may be used to maintain genetic uniformity.

• Planting density and spacing depend on species, cultivar, local climate, shade level and the degree of mechanization.

Indicative nutritional values (per 100 g roasted ground coffee)

• Energy: 330–340 kcal

• Protein: 12–14 g

• Carbohydrates: 60–65 g

  • sugars: 0 g

• Total fats: 10–15 g

  • SFA (saturated fatty acids, first occurrence): ~6–7 g

  • MUFA: ~2–3 g

  • PUFA: ~1–2 g

  • TFA (natural): trace amounts

• Dietary fiber: 0–2 g

• Minerals: potassium, magnesium, calcium, phosphorus

• Sodium: <5 mg

• Caffeine: 1–2.5% depending on species

Note: preparation uses ~7 g per espresso cup; nutritional values refer to dry matter.

Key constituents

• Alkaloids: caffeine, theobromine, theophylline

• Chlorogenic acids (CGA)

• Trigonelline

• Lipids: triglycerides, diterpenes (cafestol, kahweol)

• Complex carbohydrates and polysaccharides

• Proteins and amino acids

• Volatile aromatic compounds (800+ identified)

• Minerals (potassium, magnesium, calcium)

• Polyphenolic antioxidants

Production process

1. Cultivation and harvesting
   Hand-picking or mechanical stripping of ripe cherries.

2. Processing (removal of pulp)

   • Wet process: fermentation and washing.

   • Dry process: whole cherry sun-drying.

3. Drying
   Reduced to 10–12% moisture.

4. Hulling
   Removal of the parchment layer and sorting of green beans.

5. Roasting
   Thermal conversion generating aroma, flavor and color.

6. Grinding
   Particle size adjusted for brewing method.

7. Packaging
   Vacuum or nitrogen-flushed bags with one-way valves.

Physical properties

• Appearance: brown roasted beans, oval or round

• Density: 0.25–0.70 g/cm³ depending on roast

• Moisture: <5% after roasting

• Solubility: aromatic and soluble substances extractable in hot water

• Thermal stability: good up to ~200–220 °C before carbonization

Sensory and technological properties

• Complex aroma from hundreds of volatile compounds

• Flavor characterized by bitterness, acidity, sweetness traces and roasted notes

• Body and crema influenced by lipids and residual CO₂

• Foam-forming ability important for espresso

• Oil distribution affects crema stability

Food applications

• Beverages: espresso, moka, filter, cold brew, Turkish coffee

• Desserts: ice cream, pastries, chocolate products

• Coffee extracts and concentrates

• Ready-to-drink beverages

• Natural flavoring for foods and supplements

Nutrition and health

• Source of caffeine, which can enhance alertness and reduce fatigue

• Rich in antioxidants (especially chlorogenic acids)

• Mild thermogenic and metabolic effects

• Filtered coffee reduces diterpene intake (cafestol, kahweol)

• Moderate intake is generally safe in healthy individuals

• Sensitivity varies: possible restlessness, insomnia, tachycardia, gastric discomfort

Portion note

A standard portion corresponds to one espresso (≈30 ml) brewed from about 7 g of ground coffee.

Allergens and intolerances

• Coffee is not a common allergen

• Possible sensitivity to caffeine or gastric irritation in sensitive individuals

• Coffee-based beverages may contain allergens when mixed with milk or flavorings

Storage and shelf-life

• Whole beans: 6–12 months sealed

• Ground coffee: 2–4 weeks when vacuum-packed or valve-sealed

• Store in a cool, dry, dark place away from air and humidity

• After opening: airtight container; avoid refrigeration (condensation risk)

Safety and regulatory

• Caffeine regulated with maximum recommended intakes

• Labeling required for beverages with added caffeine >150 mg/l

• EU maximum limits for mycotoxins (e.g., ochratoxin A)

• GMP/HACCP requirements for production

Labeling

• Species indication (arabica, robusta)

• Geographical origin and processing method (washed, natural)

• Roast date (recommended)

• Grind size and intended use

• Caffeine-related warnings when applicable

Troubleshooting

• Weak aroma: grind too coarse, stale beans, poor storage

• Excessive bitterness: over-extraction, too fine grind, high temperature

• Poor crema: old coffee, wrong grind size, insufficient pressure

• Acidic flavor: under-extraction, low brewing temperature, coarse grind

• Off-flavors/mold: improper storage or excessive humidity

Sustainability and supply chain

• Environmental impact varies with cultivation method (shade-grown vs full-sun)

• Issues: water consumption, biodiversity loss, pesticide use

• Growing adoption of organic, fair trade and agroforestry systems

• By-product recovery (husks, pulp) for compost, infusions or flour

• Emission reduction efforts in roasting and transportation

INCI functions (cosmetics)

Common INCI names include Coffea Arabica (Coffee) Seed Extract, Coffea Arabica (Coffee) Powder, Caffeine.
Main functions:

• antioxidant

• toning agent

• skin conditioning

• astringent

• microcirculation support (caffeine)

• deodorant properties

Conclusion

Coffee is a complex and versatile ingredient whose value derives from a combination of botanical diversity, environmental factors and processing techniques. Its chemical richness and aromatic profile make it essential in both traditional and modern gastronomy, while its bioactive compounds contribute to functional uses in cosmetics. Proper storage, moderate consumption and attention to sustainable sourcing enhance both quality and safety.

Mini-glossary

• SFA: saturated fatty acids. Excess may raise LDL cholesterol.

• MUFA: monounsaturated fatty acids, associated with cardiovascular benefits.

• PUFA: polyunsaturated fatty acids (omega-3/omega-6) essential for cell function.

• TFA: natural trans fats found in trace amounts; different from industrial trans fats.

• GMP/HACCP: good manufacturing practices / hazard analysis and critical control points, systems ensuring food safety.

• BOD/COD: measures of organic load in wastewater (biological and chemical oxygen demand).

Studies

Chemical composition of beans (1)

• Amino acids: alanine, arginine, asparagine, aspartic acid (aspartate), cysteine, glutamic acid (glutamate), glutamine, glycine, histidine, isoleucine, leucine, lysine, methionine, hydroxyproline, phenylalanine, proline, serine, sucrose, threonine, tryptophan, tyrosine and valine. Asparagine and sucrose were the most abundant amino acid.
• Organic acids: Citric acid and Malic acid
• Phenolic acids (2) : Chlorogenic acid, Ferulic acid
• Alcaloids: Caffein
• Tepenoids: The characteristic aroma of coffee is due to α-2-furfurylthiol, 4-vinylguaiacol, some alkyl tnd 3-methylbutane yrosine derivatives, furanones, acetaldehyde, propanal, methylpropanal, and 2- acontent (3)

"Coffee, healthy aspects"

References_____________________________________________________________________

(1) Casas MI, Vaughan MJ, Bonello P, McSpadden Gardener B, Grotewold E, Alonso AP. Identification of biochemical features of defective Coffea arabica L. beans.  Food Res Int. 2017 May;95:59-67. doi: 10.1016/j.foodres.2017.02.015. 

Abstract. Coffee organoleptic properties are based in part on the quality and chemical composition of coffee beans. The presence of defective beans during processing and roasting contribute to off flavors and reduce overall cup quality. A multipronged approach was undertaken to identify specific biochemical markers for defective beans. To this end, beans were split into defective and non-defective fractions and biochemically profiled in both green and roasted states. A set of 17 compounds in green beans, including organic acids, amino acids and reducing sugars; and 35 compounds in roasted beans, dominated by volatile compounds, organic acids, sugars and sugar alcohols, were sufficient to separate the defective and non-defective fractions. Unsorted coffee was examined for the presence of the biochemical markers to test their utility in detecting defective beans. Although the green coffee marker compounds were found in all fractions, three of the roasted coffee marker compounds (1-methylpyrrole, 5-methyl- 2-furfurylfuran, and 2-methylfuran) were uniquely present in defective fractions.

(2) Affonso RC, Voytena AP, Fanan S, Pitz H, Coelho DS, Horstmann AL, Pereira A, Uarrota VG, Hillmann MC, Varela LA, Ribeiro-do-Valle RM, Maraschin M.  Phytochemical Composition, Antioxidant Activity, and the Effect of the Aqueous Extract of Coffee (Coffea arabica L.) Bean Residual Press Cake on the Skin Wound Healing. -  Oxid Med Cell Longev. 2016;2016:1923754. 

Abstract. The world coffee consumption has been growing for its appreciated taste and its beneficial effects on health. The residual biomass of coffee, originated in the food industry after oil extraction from coffee beans, called coffee beans residual press cake, has attracted interest as a source of compounds with antioxidant activity. This study investigated the chemical composition of aqueous extracts of coffee beans residual press cake (AE), their antioxidant activity, and the effect of topical application on the skin wound healing, in animal model, of hydrogels containing the AE, chlorogenic acid (CGA), allantoin (positive control), and carbopol (negative control). The treatments' performance was compared by measuring the reduction of the wound area, with superior result (p < 0.05) for the green coffee AE (78.20%) with respect to roasted coffee AE (53.71%), allantoin (70.83%), and carbopol (23.56%). CGA hydrogels reduced significantly the wound area size on the inflammatory phase, which may be associated with the well known antioxidant and anti-inflammatory actions of that compound. The topic use of the coffee AE studied improved the skin wound healing and points to an interesting biotechnological application of the coffee bean residual press cake.

(3) R.A. Buffo, C.C. Freire  -  Coffee flavour: an overview  -  Flavour Frag J, 19 (2004), pp. 99-104

(4) Patay ÉB, Bencsik T, Papp N.  - Phytochemical overview and medicinal importance of Coffea species from the past until now.  -   Asian Pac J Trop Med. 2016 Dec;9(12):1127-1135. doi: 10.1016/j.apjtm.2016.11.008. 

Koníčková D, Menšíková K, Plíhalová L, Kaňovský P. Effects of active compounds and their metabolites associated with coffee consumption on neurodegenerative disease. Nutr Res Rev. 2024 Nov 21:1-6. doi: 10.1017/S0954422424000349. 

Abstract. Coffee is one of the most known and consumed beverages worldwide. Only three species are used in commercial coffee production, that is, Coffea arabica L. (Arabica coffee), Coffea canephora Pierre ex A. Froehner (Robusta coffee) and Coffea liberica Hiern (Excelsa coffee). The world population consumes approximately two billion cups of coffee per day, making it an important commercial resource of bioactive compounds in world markets. High interest in coffee consumption described in the literature is due not only to its organoleptic properties (for example, desirable bitterness, amount of flavours and aromas) but also to its ability to stimulate the central nervous system.It is now known that there are more than 1000 compounds in coffee beverages, several of which have a bioactive activity. Recent studies show that consuming three to four cups of coffee per day, that is, moderate consumption according to the European Food Safety Authority, may be beneficial for health.The main objective of the proposed review is to provide a comprehensive overview of bioactive compounds in coffee and other caffeine-containing beverages and their effects on neurodegenerative proteinopathies.

Augustín J. Coffea arabica--production, botanical classification, new components and active agents and their pharmacological effects. Ceska Slov Farm. 2000 May;49(3):107-12. 

Abstract. The present paper surveys the latest knowledge about coffee grains (Coffea arabica) as an important part of our everyday life. It lists the botanical classification of its principal species, such as Coffea arabica, Coffea robusta, and Coffea liberica, the most important improved cultivars of production species in the world. The review paper also discusses the economic aspect, lists the most important regions of production, the optimal and farming technological conditions. It points out the occurrence of the individual constituents which have been hitherto isolated, characterized, and chemically defined with some of their physiological effects on the human organism, e.g., the substances of the diterpene type such as kafestol and kahweol and their structure.