Influência da secagem sobre as propriedades físicas dos grãos de feijão-caupi (vigna unguiculata(l.) walp)

Abstract

From a African origin, the cowpea-bean is used as hay, silage, green manure and dry grain. When leaving the field, the grain does not have the necessary conditions for an immediate storage, which leads to harm and would make it impossible for an safe storage. The good practices of storage are essential to an efficient storage, keeping the quality and quantity of product. The work aimed to evaluate the physical properties of the grains of the cowpea-bean (V unguiculata (L) Walp) submitted to different conditions of drying. The experiment was conducted at the Laboratório de Análise de Sementes, located at Universidade Federal Rural da Amazônia (UFRA), Belém Campus. The bean grains were submitted to two temperatures (40 °C and 60 °C) and two drying times (24 hours and 48 hours), total of four treatments, with three repetitions each and a testimony (grain in nature). The physical properties of the grain were evaluated: the individual mass of the grain; individual volume; real specific mass; apparent specific mass; porosity; resting angle; sphericity and dimensions (size, length, width). The drying process influenced the physical properties of the grains of the caupi bean, where the volume the individual mass and humidity content had their medium values reduce, with a gradual reducing at the humidity content of the evaluated grains; the real specific mass and the porosity increased their medium value after the drying process; at the apparent specific mass, the resting angle, sphericity and dimensions had a uneven variation at the medium data, assigned to the grains presenting a certain initial unevenness, making it difficult to evaluate thedrying process influence over those variants. Evaluating the temperature and the drying processtime, those factors influence alone the physical properties of the grains, highlighting the temperature in which the increase of temperature caused and increase of the medium value of the physical properties of the grains. On the apparent specific mass, the medium values decreased due to the temperature factor, leading up to a 0,81 g cm³ in 40ºC and 0,68 g cm³ in 60ºC. The humidity had their medium values decreased and that was the only variant influencedby temperature and drying time, when the factors acted alone, it lead to values of 9,24 % b.u (40ºC); 8,72 % b.u (24 hours); 6,91 % b.u (60ºC) and 7,43 % b.u (48 hours).