Estudo da secagem do cafe cereja descascado pelo processo a ar quente assistido a microondas

AUTOR(ES)
DATA DE PUBLICAÇÃO

1996

RESUMO

The technique of processing pulped coffee cherry beans is becoming more popular in Brazil, specially among small farmers. This is an intermediate method between the two processes used to produce the "natural" and "washed coffee", in which the ripe fruit passes through a pulping machine which removes most of the soft outer pulp or fibrous fruit flesh. There is no further removal of the mucilage, that remains coating the grain during the drying. One of the main operations for the preparation of such coffee is the drying of the product to the range from 11 to 13 % w.b., with the advantage that there is less moisture to be removed when compared to the drying of "natural coffee". In spite of this and other known advantages, associated to the original proposed process, there still subsists a few technological difficulties, related to the conventional heated air drying of the pulped coffee. Among them prevails the need for keeping the product under a limited temperature level, thus requiring the drying air temperature to be controlled to the maximum 40°C, in order to maintain the best quality of the final coffee beverage. As a consequence, the product may be damaged by long periods of drying, which can last from 30 up to 45 hours, depending on the product and operational conditions. This work concerns a process development project at the Microwave Laboratory of the Food Engineering Department, FEA/UNICAMP, aiming to the introduction of microwave energy into the conventional drying procedure of pulped coffee cherry beans. The drying cycle was subdivided into two stages, the first corresponding to an initial moisture evaporation from a content of about 47 % w.b. to an intermediate level averaging 30 % w.b., carried out in a conventional hot air batch rotary dryer, followed by a second combined treatment of heated air and microwave, developed in a novel type of a rotary cylindrical oven operating continuously, to the final 11 to 13 % w.b. moisture range. Although this is a pioneer study, the preliminary results were considered very positive, thereby justifying the establishment of a new series of experiments for the coming coffee harvesting season, in order to propitiate a microwave process optimization study.

ASSUNTO(S)

cafe - secagem microondas

ACESSO AO ARTIGO

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