Estudo do potencial de cascas do umbu (Spondia tuberosa), jabuticaba (Myrciaria cauliflora) , goiaba (Psidium guajava) na produção e recuperação da exo-poligalacturonase.

Abstract

The fruit processing industry produces a lot of agroindustrial wastes, among them husks, which are rich in carbohydrates, proteins and pectin. Pectin is a source inducing pectinases, which are enzymes that hydrolyze the pectic substances and are used in fruit juice extraction and clarification, oil extraction, treatment of textile fiber and animal feed. The aim of this study was to evaluate the potential of flours made of peels of umbu, jabuticaba and guava in the production of exo-polygalacturonase (fermentative kinetics) through solid state fermentation, using the microorganism Aspergillus niger CCT 0916 as the agent of fermentation. A factorial design with three replicates in the central point was conducted for evaluating the influence of both the initial moisture of the medium and the concentration of the nitrogen source (ammonium sulphate) on the activity of polygalacturonase. During cultivation, medium moisture, pH, reducing sugars and activity of exo-polygalacturonase (PG) were analyzed within the time range of up to 72 hours. The highest activity was achieved for the flour of umbu peels, 18 U/g of fermented medium under moisture of 60%, nitrogen concentration of 1.5%, spore concentration of 107 spores/g of fermented medium and temperature of 30°C±2°C. So this flour was chosen and from there the best condition of enzyme extraction was studied using the methodology of factorial experimental design and response surface analysis being investigated the influence of the variables agitation (AG), contact time (TC) and solvent/medium fermented mass ratio (RE) on the PG activity. The system that showed the best result of enzymatic activity, 32.59 U/g, was operated with agitation of 150 rpm, contact time of 45 minutes and solvent/medium fermented mass ratio (RE) of 10 mL/g. The application of liquid-liquid extraction for separating exopolygalacturonase from the flour of umbu peels was also investigated by using the two-phase aqueous system (SAB) made up of polyethylene glycol (PEG), potassium phosphate and the raw extract from the fermentation carried out under the best conditions of extraction. The effect of PEG molar mass, PEG concentration and potassium phosphate concentration on the purification factor (FP) was evaluated as well as the concentration (Ri) in the lower phase in each system by using a 23 factorial experimental design and response surface analysis. The partition of exo-polygalacturonase was conducted in systems with composition of PEG and potassium phosphate concentration of 12, 14 and 16% and PEG molar mass of 4000, 6000 and 8000. The system with the highest purification factor (FP), 5.64 times and recovery (R£) of 97.14, had concentration of PEG 8000 of 16% and potassium phosphate concentration of 12%. This shows that the aqueous two-phase system (SAB) can be considered as an alternative in planning processes of recovery and purification of the enzyme studied obtained from the flour of umbu peels