ABSTRACT This study aimed to determine if the quality of macauba pulp oil is affected by drying the whole fruits at 60 ºC. Mature fruits were collected at every five days on the ground under 10 palm trees. A mixed batch of 3 kg of whole fruits, with three replications each, was dried in an oven with air circulation for 0, 12, 24, 36 and 48 h at 60 ºC. After every drying time, dried fruits were pulped using an automated device, followed by oil extraction with hexane. Moisture and oil content were determined in the pulp, and the pulp oil quality was analyzed for fatty acid composition, free fatty acids content, peroxide value, molar absorptivity at 232 and 270 nm, refractive index, and total carotene content. The tested temperature was sufficient to decrease moisture to a range suitable for automated pulping, with the best combination and easier pulping being reached after 24 h of drying. In the first 12 h there was an apparent synthesis of unsaturated fatty acids and carotenes. The tested temperature was insufficient to avoid the enhancement of acidity since the beginning and throughout the drying period, nor the degradation of polyunsaturated fatty acids. Thus, it is concluded that drying of fresh fruits of macauba palm at 60 ºC is not appropriate to obtain an overall good quality pulp oil for industrial purposes.

O objetivo deste trabalho foi realizar caracterização química de sementes e de tortas de pinhão-manso (Jatropha curcas), nabo-forrageiro (Raphanus sativus) e crambe (Crambe abyssinica) após a extração do óleo por prensagem mecânica. Sementes inteiras dessas espécies foram submetidas à dupla prensagem a frio para extração do óleo, produto principal, e da torta, coproduto. Os grãos e tortas foram avaliados quanto à composição bromatológica e ao perfil de minerais. Os rendimentos de extração lipídica foram calculados com base no balanço de massas. O teor de lipídeos nas tortas foi baixo quando comparado aos valores da literatura, o que caracteriza boa eficiência de extração e versatilidade da prensa empregada. A torta de pinhão-manso apresenta fibras como principal componente, com cerca de 1/3 de sua composição total. As proteínas constituem a fração majoritária na torta de nabo-forrageiro, e o crambe apresenta composição balanceada entre fibras e proteínas. As tortas são ricas em potássio, magnésio, cálcio, sódio, manganês, ferro, zinco e boro.

The objective of this work was to chemically characterize the seeds and presscakes of physic nut (Jatropha curcas), radish (Raphanus sativus) and crambe (Crambe abyssinica) after extracting the oil with a mechanical press. Whole seeds of these species were subjected to double cold pressing to extract the oil, or main product, and the presscake, or coproduct. The seeds and presscakes were evaluated regarding proximate composition and mineral profile. The lipid contents in the presscakes were lower when compared to the values presented in previous works, which characterizes good extraction efficiency and versatility of the employed press. Fibers are the most abundant component of physic nut presscakes, and comprise about 1/3 of their total composition. Protein is the largest fraction in radish presscakes, and crambe presents balanced fiber and protein contents. The presscakes are rich in potassium, magnesium, calcium, sodium, manganese, iron, zinc and boron.

Soil CO2 emissions represent an important component of carbon global cycle. However, information about short-term alterations of CO2 fluxes in soils of tropical regions are scarce. So, the objective of this study was to evaluate such variations in coffee plantations in Latosol (Oxisol). The CO2 emissions were not affected by environmental abiotic factors, such as temperature and soil water evaporation, but they were significantly correlated with the carbon content of microbial biomass (R=0.90, P<0.05). It happens a close relationship between root activity and soil CO2 emission in coffee plantations.

Avaliou-se o efeito de sistemas de preparo do solo e de doses de nitrogênio, na produção de matéria seca, grãos e palhada, bem como no acúmulo de N, P, K, Ca, Mg, S e Zn, por plantas de milho (Zea mays L.). O experimento foi conduzido, sob irrigação, em um Latossolo Vermelho-Escuro sob vegetação de cerrado, em área experimental da Embrapa-Centro Nacional de Pesquisa de Milho e Sorgo, Sete Lagoas, MG. Os sistemas de preparo do solo estudados foram: plantio direto, plantio convencional com arado de discos, e plantio convencional com arado de aiveca. As doses de nitrogênio, 0, 60, 120 e 240 kg ha-1 de N, foram aplicadas em cobertura. As maiores produções de matéria seca de grãos e de palhada e de acúmulo de nutrientes foram obtidas sob o sistema de plantio direto. Na dose de 60 kg ha-1 de N, ocorreu a maior eficiência da utilização do N pela cultura, constatada pela maior recuperação do N aplicado.

The effects of soil preparation and doses of nitrogen on grain and straw dry matter production and N, P, K, Ca, Mg, S and Zn accumulation by corn plants (Zea mays L.) cultivated under irrigation were evaluated in a field experiment in a Dark Red Latosol (Oxisol), originally under cerrado vegetation, at Embrapa-Centro Nacional de Pesquisa de Milho e Sorgo experimental station, in Sete Lagoas, MG, Brazil, from November, 1995 to June, 1996. The soil preparation systems studied were: no till, conventional till with disk plow and conventional till with moldboard plow. The nitrogen doses were: 0, 60, 120 and 240 kg ha-1 N, applied in cover. The highest productions of grains and straw dry matter and nutrients accumulation were obtained in the no till system. In the doses of 60 kg ha-1 N, the greatest efficiency and the highest recover of applied N by the crop occurred.