Desenvolvimento do fruto de Butia capitata (Arecaceae) : aspectos estruturais, ultraestruturais e físico-químicos

Abstract

Palm fruits are rich in reserve compounds widely used in food and with several industrial applications. However, information on their development and postharvest is still scarce. Butia capitata (coquinho-azedo) is an endemic palm from Cerrado, threat of extinction, it produces fruits used for the manufacture of juices and ice cream and with potential for incorporation into the productive system. In the first chapter of this thesis, the objective was to characterize the development of the fruit and the ontogeny of the pericarp of the species. It was concluded that the fruit develops in about 84 days, in three phases: I - histogenesis (up to 42 days after anthesis, DAA); II – endocarp maturation (42 to 70 DAA) and III - mesocarp maturation (70 to 84 DAA). The ontogenesis of the pericarp involves the following events: the outer epidermis and the outer mesophyll of the ovary originate the exocarp; the median ovarian mesophyll differentiates into the outer mesocarp; the inner ovarian mesophyll originates the inner mesocarp and stony endocarp; the inner ovarian epidermis integrates with the endocarp and, in the micropylar region, it differentiates into the germination pore plate, a structure that protects the embryo and controls germination. In the second chapter, the objective was to associate the physicochemical and cytological indicators involved in the maturation and senescence of the pulp (exocarp + mesocarp) of the fruit. The physiological maturity of the pulp is reached at the time of abscission (= harvest point), on average at 89 DAA. In this point, the fruits present a yellow-orange aspect, juicy and fibrous, juice with pronounced acidity (pH 3.3), maximum dry mass and deposition of mesocarp reserves (mucilage in vacuole, starch and carotenoids in plastids, lipids and proteins in cytosol), high levels of soluble solids (SS) (degradation of starch into sugars), reduced content of phenolic compounds in the vacuoles and soft texture (weakening of the median lamella and cell walls in the mesocarpal parenchyma). Pulp senescence is characterized by progressive decline in firmness (intense loosening and disintegration of cell walls, dissolution of the median lamella and enlargement of intercellular spaces), reduction of reserves and acidity, elevation of SS and phenolic compounds, and collapse of the mesocarp cell protoplast. The information generated, largely unknown for the Arecaceae family, is useful to support genetic improvement programs of B. capitata and for the development of production technologies, including fruit set and postharvest management.