Arabica coffee is cultivated at altitude between 1000 to 1200m in equatorial regions, or at altitudes between 400-1200m in regions further away from the equator, in order to have a temperature of about 18-22°C. Minimum rainfall of 1200-1500mm with no more than 3 months of less than 70mm is preferable for good growth and production. The higher the altitude, the cooler the climate which brings about better quality of arabica coffee, due to its higher acidic content (ie. richer in sugars and soluble solids). Too cold temperature will kill the leaves immediately, while too hot weather will cause abnormal flowering and shoot dieback.
Robusta, on the other hand, requires warm and humid climates at low altitude of 100-1000m with daily temperature averaging between 22-26°C. Average rainfall should be at least 2000mm.
In general, coffee soils include lava and tuff, volcanic ash, basalt and granite. They should also be at least 2m deep with good water-holding capacity, fertile and slight acidity of 5-6 pH.
Depending on the climate and soil, incidence of diseases and pests, cropping systems, socio-economic factors, market dynamics and consumer preferences, coffee growers will select the cultivars that brings the optimum economic returns. Traditional cultivars that are susceptible to disease include Typical, Bourbon and Caturra used worldwide, Kona in Hawaii, Mundo Novo and Catuai in Brazil, Blue mountain in Jamaica, Kent in India, K7, SL28 and SL34 in Kenya, KP423 and N39 in Tarzania, Jimma, Harar, Gimbi, Yirgachefe and Limu in Ethiopia, Villa Sarchi in Costa Rica, and Pacas in El Salvador, just to name a few.
With research and developments, new cultivars resistant to diseases (eg. Coffee leaf rust, coffee berry disease, black rot, etc) have been developed. These include Catimor and Sarchimor used worldwide, Colombia in Colombia, S795 and S828 in India, Ruiru II in Kenya, Ababuna in Ethiopia, and Icatu in Brazil.
Factors affecting the quality of green bean
Environment – altitude and temperature can influence the quality. High altitude is important for arabica cultivation around the equator because of the warm and humid weather. Moderate temperatures will favor a slow and uniform maturation process of coffee berries and especially wide amplitude between day and night temperature will increase flavors and aromatic precursors in the beans.
Cultural practices – Nitrogen, potassium, calcium, zinc and boron are important essential elements in coffee plantation. Nitrogen is necessary for amino acid and protein build-up. Potassium influences total sugar and citric acid contents. Calcium is important for cell wall formation, providing more compact beans and resistance to pathogen attacks, just like its benefits to human being. Zinc influences protein and carbohydrate metabolism. Boron affects yield by influencing flowering and fruit set.
Genotype of the cultivar - Modern cultivars are compared with the traditional cultivars such as the Bourbon, Blue Mountain, Kent and SL28. Different cultivars have impact on the cup quality including aroma, flavor and body. Typically, arabica has lower levels of caffeine. amino acids and chlorogenic acids compared to robusta, but it has 60% more total oils. During roasting, sugars are reduced upon caramelization leading to bitterness, so ideal sugar content and relative lipid fractions must be determined.
Post-harvest handling. For example, wet process favors a lighter body and acid beverage, whereas dry or semi-dry processes lead to enhanced body with reduced acidity
