Obtenção de polpa de manga em pó pelo processo de liofilização

Abstract

The objective was to obtain powdered mango pulp through the freeze-drying process, establishing the best condition for drying as a function of the maltodextrin concentration and the drying time. The physical and physicochemical characterization of the whole mango pulp and powder were evaluated, in the hygroscopic behavior, solubility, determination of degree of the caking. With the powdered mango pulp stability study was performed, adsorption isotherms were elaborated, scanning electron microscopy and rheological properties were analyzed. The fresh mangoes were purchased from EMBRAPA Petrolina - PE, pulped at EMBRAPA tropical agroindustry (Fortaleza - Ceará) and sent to the quality control and food drying laboratory. The experimental design worked with 24 and 30 hours of drying and 0, 10, 20 and 30% of maltodextrin. From the analysis of the most considerable parameters, the best condition chosen for lyophilizer mango drying was 20% maltodextrin and 24 hours drying. The characterization revealed a decrease in moisture content, water activity, color parameters a * and b * and a consequent increase in total soluble solids values, ascorbic acid content, acidity, pH, total and reducing sugars, and the parameter L *. The stability study was performed with the powder obtained from the best drying condition stored for 90 days, with physical and physical-chemical analyzes every 15 days. The storage was done at room temperature in laminated packaging with and without vacuum and plastic with and without vacuum. The use of the laminated material was presented as more efficient to maintain the quality of the powder in relation to moisture, water activity and total soluble solids content. The vacuum-laminated package presented the best values for maintaining the ascorbic acid content, hygroscopicity, parameter b * and a * of color, due to the easy degradation of ascorbic acid and color-related compounds in the presence of light and oxygen. From the scanning electron microscopy, it was observed powder with amorphous properties, in which the increase in the concentration of maltodextrin caused an increase in the number of pores and decrease in the diameter of the particles. The GAB model was the one that best adjusted the isotherms of the mango pulp, presenting type III curve. The rheological of the powder, through the flow index characterized the product as a powder with a tendency to cohesive flow. The incorporation of maltodextrin caused an increase in the apparent density of the powder, however it had an inverse effect on the values of the effective angle of internal friction and the angle of internal friction with the wall.