Coffee Production and Trade

Coffee harvesting

Selective picking - Uganda

Generally coffee is harvested annually¹ when the coffee cherries are ripe, i.e. bright red, glossy, and firm to the touch. Harvest times vary according to geographic zone, but harvest generally takes place north of the equator between September and March, and south of the equator between April and May.

There are three harvesting methods:

• Selective picking - ripe cherries are individually picked by hand, usually only used for arabica
• Strip picking / stripping - all cherries, including unripe and overripe cherries, are stripped from the tree simultaneously
• Mechanical harvesting - all cherries are collected using a specially designed harvesting machine

Mechanical harvester - Brazil

Selectively picking ripe cherries by hand obviously maximises the amount of ripe coffee harvested, as unripe, green beans are left to mature and be harvested at a later stage, and overripe cherries are avoided. In this way, an early quality control exercise on the product is completed. From a quality perspective, it is better to avoid the use of immature cherries, and from an OTA perspective, the removal of overripe cherries, in certain situations, may be regarded as a useful OTA-prevention measure. Moreover, harvesting cherries from the soil should be avoided as they can be highly contaminated with fungal spores, and thus present a high OTA risk.

Economic factors are crucial in determining the harvesting method selected. Harvesting the same tree several times can be more costly than subsequently separating and discarding unripe or overripe cherries included in a strip harvest. Indeed, selective hand harvesting is the most expensive part of coffee production – typically, between 5 and 10 'passes' are required during a typical harvest.

Another factor that is important in deciding to strip harvest is the level of uniformity of cherry maturation, which depends on the variety being cropped. In Brazil strip harvesting usually commences when 75% of the crop is perfectly ripe.

Mechanical harvesting has become increasingly sophisticated since the 1970s, and is now widely used in Brazil. However, mechanised harvesting is more than just the simple introduction of a machine - hedgerow plantings need to be adopted with appropriate spacing regimes, and it is best suited in environments where there is a significant synchronisation of flowering and extended cherry life (Norris, 2001).

Irrespective of the harvesting method used, between 12-20 kg of export ready green coffee is produced from 100 kg of ripe coffee cherries.

¹ In some origins there is more than one harvesting season, with a secondary or 'fly' harvest taking place as a result of a second flowering period, the existence of which is dependent on the prevailing climate, especially rainfall patterns.