Preparação e aplicação de revestimento comestível em laranjas cv. Valencia Delta à partir de galactomanano de sementes de algaroba (Prosopis juliflora (sw)D.C.)

Abstract

The application of tree legume seeds has been each day more studied because of its use in several industrial areas such as cosmetic, pharmaceutical and food, whether for humans or animals. The “algarobeira” (Prosopis juliflora Sw.) is an example of Leguminosae found throughout Northeastern Brazil. It is a plant capable of developing and surviving in environments with soil of low humidity, high temperatures, and low precipitations, which are sufficient reasons for its diffusion in the region, enabling animals and man to obtain subsidies necessary to overcome drought periods. Seeds of the algaroba tree are sources of galactomannan, a polysaccharide that has desirable rheological properties which highlight its use as a stabilizer, thickener, and dispersant. This study aimed to evaluate the use of galactomannan from seeds of algaroba as an edible coating on 'Valencia Delta' orange fruit, produced in a semi-arid climate area, aiming at evaluating its use to increase fruit shelf-life. Oranges produced in the region of “Baixo Jaguaribe” (Ceará State, Brazil) were coated with galactomannan at concentrations of 1.0, 1.5 and 2.0% and stored at room temperature (25 ± 2ºC) and refrigerated temperature (8 ± 2ºC) for 28 and 42 days, respectively. The coated fruits were evaluated as for physical parameters (loss of mass, firmness, peel thickness, and color), physicochemical characteristics (titratable acidity, pH, soluble solids, total and reducing sugars, ascorbic acid, carotenoids, phenolic compounds, yellow flavonoids, and chlorophyll) and antioxidant capacity, every 7 days. The coating aided in the maintenance of the fruit firmness and color and reduced the mass loss in the two studied temperatures. The increased concentration of galactomannan edible coating significantly influenced the physical and physicochemical parameters, which were preserved for longer (p<0.05) compared to the uncoated fruits, and the coating containing 1.5% galactomannan better contributed to this maintenance, as can also be observed in antioxidant capacity (p<0.01). The use of galactomannan polysaccharide as a coating prolonged the useful life of oranges and can be used as a natural material to replace the currently used waxes.