Produção, avaliação da estabilidade e aplicação de enzimas pectinolíticas de Aspergillus niger IOC 4003 utilizando resíduos de frutas tropicais como substrato

Abstract

During the last decades, it has increased significantly the demand for microbial enzymes on biotechnological applications. The pectinolytic enzymes are responsible for cleaving both pectin and other pectic polysaccharides in galacturonic acid monomers and they have application in several industrial sectors such as fruit and wine juice processing, essential oil recovery, vegetable oil extraction, textile industry and, paper and cellulose industry. In this context, this work aimed to evaluate production, stability and application of pectinolytic enzymes by Aspergillus niger IOC 4003 using acerola and yellow mombin wastes as substrate for solid-state fermentation (SSF). Initially, acerola and yellow mombin wastes, washed and unwashed, were submitted to a drying process and they had their chemical and physicochemical composition determined. The percentage of calcium pectate - pectin indicator - found in wastes was 3.46 ± 0.11 %; 2.94 ± 0.18 %; 5.85 ± 0.01 % and 5.34 ± 0.23 % for unwashed acerola, washed acerola, unwashed yellow mombin and washed yellow mombin, respectively. Hereby, the potential of these substrates as inducers was evaluated for the production of pectinolytic enzymes for SSF during 240 h with initial pH of 4.5; moisture at 40% and spore concentration of 1 x 107 spores / mL. In the fermentation stage, the greatest polygalacturonase production was observed using washed yellow mombin waste reaching enzymatic concentration of 38.22 ± 0.63 U / g in 72 h of cultivation. Furthermore, it have been carried out the optimization of enzyme extraction and the best condition of extraction occurred using acetate buffer (50 mM, pH 5.4) and 30 minutes of contact time. On the subsequent step, the stability of enzyme complex was evaluated against different temperatures and pHs. The greatest condition on stability of polygalacturonase occurred at temperatures of 30 and 40 °C, and among pHs 4 and 6 for up to two hours of incubation. Thus, the synthesized enzymatic extract by Aspergillus niger IOC 4003 from washed yellow mombin or unwashed acerola wastes was applied in process of clarifying yellow mombin juice. At the clarification stage, the outstanding results were 40% reduction in turbidity, 50% in viscosity, 30% in clarification and 85% increasing of antioxidant capacity in the juice. Therefore, this study demonstrated the feasibility of using fruit residues of the industry as substrates for production of interest enzymes and its application in the food industry.