ESTUDO COMPARATIVO DA CONSERVAÇÃO DE CASTANHA-DO-BRASIL ( Bertholletia excelsa) SECA POR MICROONDAS E CONVENCIONALMENTE

Estudou-se comparativamente a conservacao de amendoas de castanha-do-Brasil secas por microondas e por processo convencional. Os dois procedimentos de secagem foram desenvolvidos em fornos domesticos, adaptados com sistema externo de provisao de ar quente. Testes foram estabelecidos a partir de planejamentos experimentais, utilizando combinacoes de densidade de potencia (W/g), temperatura e velocidade do ar. As respostas de ambos os processos foram tempo de secagem, atividade de agua (AW) e niveis de rancificacao, dados pelos indices de peroxido (PI) e de estabilidade oxidativa (OSI). Os valores de AW, PI e OSI foram obtidos ao longo de seis meses de estocagem da amendoa seca embalada. Os resultados obedeceram os intervalos: AW≤0,60; 8,8 meq/ 1000 g oleo ≤PI ≤14,9 meq/1000 g oleo; 5 h ≤OSI ≤7,4 h, enquadrados nos limites encontrados na literatura e estabelecidos pela legislacao brasileira. Concluiu-se que e possivel obter produtos com qualidade adequadamente preservada pelo uso de microondas na secagem da castanha-do-Brasil. COMPARATIVE STUDY OF BRAZIL NUTS (Bertholletia excelsa) CONSERVATION DRIED CONVENTIONALLY AND BY MICROWAVE Abstract The conservation of Brazil nuts kernels dried by microwave and by conventional process was comparatively studied. Two drying procedures were developed in domestic ovens, adapted with an external air supply system. Tests were established from experimental designs, utilizing combinations of potence density (W/g), temperature and air velocity. The reponses of both processes were drying time, water activity (Aw) and rancidity levels, given by peroxide indexes (PI) and oxidative stability (OIS). The values of Aw,, PI and OSI were obtained during six months of storage of the packed dried kernels. The results were within the ranges Aw £ 0.60; 8.8 meq/1000 g oil, PI £ 14.9 meq/ 1000 g oil; 5 h OSI £ 7.4 h, following the limits found in literature and established by Brazilian legislation. It was concluded that is possible to obtain products with quality adequatelly preserved by the use of microwave in the drying of Brazil nuts.