Ocorrência dos principais defeitos do café em várias fases de maturação dos frutos

Abstract

A ocorrência dos principais defeitos do café — grãos de película verde, grãos prêtos e grãos ardidos — foi estudada nos anos de 1967 e 1968, em Campinas, colhendo-se plantas, mensalmente, de abril a março do ano seguinte. Em cada colheita a produção total foi separada nas frações frutos verdes, meio maduro, maduro, passa, sêco normal, "sêco anormal" e café do chão. Nessas frações foi determinada a presença dos referidos defeitos. O defeito, "grão verde", em várias tonalidades, foi encontrado com maior freqüência nas frações de frutos verdes e, em ordem decrescente, nas frações sêco anormal, meio maduro, maduro, passa, sêco normal e sêco do chão. Os dados mostram que os chamados grãos verdes na verdade não provêm exclusivamente de frutos colhidos verdes, pois ocorreram com freqüência em todas as frações estudadas. Os grãos ardidos tiveram freqüência mais elevada na fração sêco do chão e decresceram nas frações sêco normal, sêco anormal, verde, meio maduro, maduro e passa. Essa ocorrência, em todas as frações estudadas, indica que tal defeito deve resultar de várias causas, e não apenas de fermentações anormais, como geralmente é considerado. O defeito "grão preto" apareceu com maior freqüência no café seco do chão e, em ordem decrescente, nos frutos seco normal e seco anormal, não ocorrendo nas demais frações. Os resultados mostram a conveniência de colher apenas o café maduro, quando então se verifica a menor quantidade dos defeitos estudados. Sugerem também ser recomendável uma revisão na designação dos defeitos, a fim de evitar interpretações errôneas na classificação comercial.

The occurrence of green-coated beans, brown and black beans was studied in samples of green fruits, under-riped (plant stage) fully riped and over-riped berries, as well as in the normal and abnormal fruits which were dried on the trees and also in the fruits fallen on the ground. The samples were monthly collected during the year 1967 and 1968. The so-called abnormal dried fruits have a dull black exocarp, whereas the normal ones have bright black colored shells. The total production of three plants was harvested every month, separated according to the different ripening stages, and then, after drying, were shelled and the proportion of defective beans was scored. The data showed that the so-called green coated beans appear in significant proportions in all stages studied. The highest percentage of these was found in the unriped fruits and in the abnormal dried fruits. Its occurrence decreases as the fruits become more and more mature. The lowest percentage was found in the samples of dried fruits which had fallen on the ground. The green color is produced by the silver skin which retains the green pigment, probably chrolophyll. The brown beans appear more frequently in the fallen fruits and they also occur in a decreasing proportion in the normal and abnormal dried berries and from unriped to overriped fruits. This type have been considered to be caused by over-fermentation, however our results indicate that it may have other causes, due to their appearance even in the unriped fruits. The high percentage of brown beans in the fruits dried on the tree indicates that the berries must be harvested in the cherry stage to have a high quality product. The black beans, characterized were more frequently found in the dried fruits fallen on the ground. the black beans represent a more the endosperm. The initial stages the different shades of brown. exclusively by the black endosperm, berries dried on the tree or in the It seems reasonable to assume that advanced stage of deterioration of would, probably, be characterized by Based on these findings it is proposed a revision on the defective beans nomenclature in Brazil. Considering the Brazilian system of coffee classification it was suggested that for the nomenclature of the defective beans more emphasis should be made in the origin of such defects rather than in the general aspect of the beans.