Immature Bean



Immature Bean
Immature Bean
Española: Inmaduro
Français: Immature
Immature / Unripe beans are a Secondary (Category 2) defect: 5 beans = 1 full defect
Immature or unripe beans are identified by shape, texture and color of
the tegument or silver skin. They are often smaller and curved inward in a concave shape with sharp edges; the texture is usually rough and fibrous with a color ranging from bright greenish, yellow-greenish, grayish or brownish to almost black. The silver skin of an immature bean is tightly attached to the bean and is difficult to scratch with a fingernail. In many cases, one may need to use a piece of sand paper to determine if the interior is affected, in which case it may be a black or partial black bean.
Cup:Generally imparts grassy, greenish, straw-like, cereal or bitter flavors and is the main source of astringency in coffee.
Consideration:Primary source of quakers, a defect in roasted coffee
Cause(s):AGRICULTURAL: Strip or mechanical picking are the primary causes of immature beans. Uneven flowering may cause inconsistent ripening schedules that complicate proper selective picking of ripe cherries. Even in those cases where an immature bean has reached full size, it will often lack the density and sugar content of a fully mature bean.
Remedies:AGRICULTURAL: Immature beans can be avoided through sound crop planning, by introducing appropriate varieties to each microclimate and by selectively picking only fully ripe cherries.   Cultivating early maturing varieties at medium to high altitudes and the use of irrigation to synchronize flowering will minimize the presence of unripe cherries a picking times.
PROCESSING: Some immature beans can be removed during both wet and dry processing. At the wet mill, some non-pulped cherries containing immature beans can be separated with screens immediately after the pulping process (green bean separators).Lightweight immature beans can be removed by a density sorter or gravity table at the dry mill; however, full size, near-full weight immature beans cannot be removed by a gravity table. Sensitive color sorting equipment can be used to separate some gray, brown and black unripe beans.