Paulo Cesar Afonso Junior

DETERMINAÇÃO DOS PARÂMETROS DE SECAGEM EM CAMADA DELGADA DE SEMENTES DE MILHO DOCE (Zea mays L.)

Com o objetivo de verificar se a posicao da semente na espiga afeta diferentemente a produtividade e outros caracteres da planta e se essa diferenca pode ser ampliada por meio de ciclos seletivos, foi conduzido o presente trabalho. Para isto, na safra 1995/1996, foram semeadas, em lote isolado, cerca de 3.000 plantas da populacao CMS-39 e, por ocasiao da colheita, tomadas 300 espigas ao acaso. De cada espiga, foram coletadas sementes das extremidades e, posteriormente, as sementes da ponta de cada espiga foram misturadas e o mesmo foi realizado com as sementes da base. Esse procedimento foi repetido de modo analogo por cinco ciclos seletivos. As dez subpopulacoes, cinco da ponta e cinco da base, foram avaliadas em experimentos conduzidos nas safras 2000/2001 e 2001/2002. O delineamento utilizado foi o de blocos casualizados, com seis repeticoes, segundo esquema de parcelas subdivididas. Os tratamentos nas parcelas foram os cinco ciclos seletivos e, nas subparcelas, a origem das sementes, ponta ou base. Foram considerados os caracteres numero de dias para o florescimento masculino e feminino, altura de espiga e produtividade de graos. Constatou-se que a origem da semente da ponta ou da base nao alterou a expressao de varios caracteres avaliados e nao foi possivel, com a precisao experimental obtida, detectar efeito da selecao indireta para o vigor de polen pela posicao dos graos na espiga, em todos os caracteres considerados.

Variação das dimensões características e da forma dos frutos de café durante o processo de secagem

The present work had as objective to evaluate the effect of moisture content variation on dimensions and physical properties (sphericity and roundness) of coffee fruit of the arabica and canephora species, for different varieties. The obtained results show that the reduction of moisture content affects in an accentuated way the physical characteristics of coffee fruit of the studied species and varieties, indicating that the variations of dimensions of the fruit along the drying process are important. Further, the mathematical expressions adjusted to the data were satisfactory for the studied phenomena.

Efeito do nível e do tamanho de impurezas nas propriedades físicas da massa granular de feijão

The objective of this study was to determine experimentally the values of bulk density and porosity for grains of the Carioquinha and Jalo varieties of bean and to adjust mathematical equations to the experimental data, as a function of level and size of impurities in the product mass. The results obtained in this work point to the conclusion that the increase of the level of impurities smaller than the grains increased the bulk density and reduced the porosity, and that the increase of the level of larger impurities than the grains reduced the bulk density and increased the porosity of the granular product for both the varieties. The values of bulk density and porosity of the mass of bean grains differed among the analyzed varieties, the values of the bulk density of the variety Carioquinha being superior, while the porosity value was found to be inferior to that observed for the variety Jalo, for moisture content of 12% wet base.

Thin Layer Drying Equations for Natural Coffee and Parchment Coffee

In this paper, thin layer-drying equations for natural coffee and for parchment coffee are presented. Laboratory tests were performed using air-drying temperatures of 30, 40, 50 and 60 degrees celsius and relative humidity of 30%, 40%, 50% and 60%. By using nonlinear regression analysis, thin layer drying equations were obtained. Different types of thin layer drying models were tested to find the one that fitted better to the experimental data.

Intermittent Coffee Drying Simulation Models

Natural and parchment coffee are generally dried using intermittent type dryers. This is due to high initial moisture content of the product. Quality and energy are very important factors when analyzing coffee drying. In this paper, a set of simulation models is presented to simulate fixed bed, concurrent flow, countercurrent flow, cross flow and drum type dryers. A computer program was implemented using Visual Basic 6.0 based on this set of models. The drying process is animated so the user can visualize what is going on during the process. Airflow reversion and airflow recovery are allowed. The computer simulation model is a useful tool for coffee dryer design.

Modeling of quality loss of soybean seeds as a function of initial conditions and of storage atmosphere

In order to predict the germination potencial of soybean seeds of the Santa Rosa variety during storage, an experiment was conducted, The seeds with initial moisture content of 0.333 (dry basis) were dried under an air temperature of 30 oC and relative humidity of 40% until the moisture content of 0.111; 0.176 and 0.250 (dry basis) were reached. The seeds were conditioned in paper bags and maintained under different storage temperatures (5, 10, 20 and 30 °C). The seed viability was evaluated just after drying and every 10 days, during 60 days, applying the standard germination test. In general, for the majority of the tests, the temperature and the moisture content affected the seed germination during the storage period. However, for the storage temperatures of 5 and 10 °C the seeds maintained the viability at satisfactory levels, independently of the moisture content of the product. The experimental results of germination were evaluated by adjusting the data to the exponential and probit mathematical models. The results obtained in this work lead to the conclusion that the temperature and the moisture content of the stored soybean seeds affect their germination and that the exponential model better fits the experimental data.