Abstract
Bean is a popular name for a large variety of seeds from Leguminosae family. Beans are very important in human and animal diet because it´s a rich source of fiber, proteins, carbohydrates, vitamins B-complex and minerals, at relatively low cost. The Vigna unguiculata specie, known as cowpea-bean is widely consumed in the North and Northeast regions of Brazil, featuring the typical cuisine of these regions, in which the most famous dish is called Acarajé. This legume is also widely consumed in many African countries. The species Phaseolus vulgaris, the common-bean, alongside of rice is part of the daily diet in many parts of the world, composing one of the most nutritionally complete meals. This study aimed to achieve, by the optical microscopy techniques, the anatomical structure characterization of seeds of common-bean variety black, and cowpea-bean, as well as evaluation of starch granules present in grains in the forms raw, and cooked in a pressure cooker. Slides were prepared by the techniques of free-hand cut, and cut with the microtome in which the samples were previously embedded in paraffin. In the images of raw cotyledon samples under polarized light, the typical model of "Maltese cross" resulting by birefringence of the crystalline regions of the starch granule and the spherical structure was observed. In the images of cotyledon of the cowpea cooked samples, with polarized light, was not observed the starches granules, indicating a loss of molecular ordering due to heat greater than 120°F, but in the samples of cooked black bean, the granules of starch is present, may indicate a long time of grain storage. Three tissues layers can be observed in the images of hand-free-cut integument: epidermis, hypodermis and palisade parenchyma. The samples prepared by embedment in paraffin had their structures palisade disrupted, suggesting that the samples are suffering interference by technique.
