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a b s t r a c tThis work evaluated the microfiltration process for the clarification of passion fruit juice. Moreover, the influence of some pretreatments (centrifugation, enzymatic liquefaction and chitosan coagulation) before passion fruit juice microfiltration was analyzed. Enzymatic treatment reduced the juice viscosity, and centrifugation step was important for colour and turbidity reductions. Chitosan addition was the most promising pretreatment, since it provides the highest reductions of colour and turbidity, enabling the highest permeate flux in the microfiltration process of pretreated passion fruit juice. The microfiltration process with hollow fibre membranes resulted in a clean passion fruit juice, almost free of turbidity. The applied pretreatment did not influence the characteristics of the obtained permeate. According to the obtained results, the predominant fouling mechanism depends on the applied pretreatment. In centrifuged and enzymatic treated samples, cake formation was found to be the major fouling factor, while internal pore blocking occurred during the filtration of the chitosan pretreated sample.

RESUMO -Este trabalho objetivou estimar o ganho genético obtido pelo programa de melhoramento de arroz de sequeiro (Oryza sativa L.) desenvolvido em Minas Gerais cooperativamente pela Epamig/Embrapa-Centro Nacional de Pesquisa de Arroz e Feijão (CNPAF)/UFLA/UFV, no período de 1974/75 a 1994/95. Para tanto, utilizaram-se os dados dos ensaios comparativos avançados de cultivares e linhagens de arroz de sequeiro conduzidos no referido período. Em virtude da distribuição irregular de chuvas e da resposta diferenciada dos materiais de ciclos diferentes às condições climáticas, optouse por dividi-los em dois grupos; um contendo os genótipos precoces e o outro os de ciclo médio. Os resultados alcançados mostraram que ocorreu um ganho genético médio anual de 1,26% e de 3,37% em relação ao grupo precoce e ao de ciclo médio, respectivamente. O grupo precoce superou estatisticamente (P≤0,01) em produtividade de grãos o grupo de ciclo médio, indicando que em Minas Gerais deve-se dar preferência ao plantio de cultivares de ciclo curto.Termos para indexação: Oryza sativa, ganho genético, avaliação de genótipos, cultivar. GENETIC PROGRESS OBTAINED BY UPLAND RICE BREEDING IN TWENTY ONE YEARS OF RESEARCH IN THE STATE OF MINAS GERAIS, BRAZILABSTRACT -This work aimed to estimate the genetic gain obtained by the upland rice (Oryza sativa L.) breeding program developed in Minas Gerais State, Brazil, in cooperation with Empresa de Pesquisa Agropecuária de Minas Gerais (Epamig), Embrapa-Centro Nacional de Pesquisa de Arroz e Feijão (CNPAF), Universidade Federal de Lavras (UFLA) and Universidade Federal de Viçosa (UFV), from 1974/75 to 1994/95. Results of the comparative trials of upland rice cultivars and lines conducted over the above quoted period were utilized. Because of irregular rainfall distribuition and the distinctive response of different cycles to climatic conditions, the option was to divide them into two groups, one encompassing the early genotypes and the other those of medium cycle. The achieved result showed that an average genetic gain of 1.26% and 3.37% for the early group and medium cycle, respectively, occurred. In addition, it was found that the early group statistically outyielded (P ≤ 0.01) as to grains the medium cycle group, denoting that in Minas Gerais the short cycle cultivars should be preferred.