Production, stability and application of pectinolytic enzymes from Aspergillus niger IOC 4003 using tropical residues of fruits as substrate
Aspergillus niger, solid-state fermentation, pectinases, pectin lyase, polygalacturonase, agro-industrial residue.
At the last decades, it has increased significantly the demand for microbial enzymes on biotechnological applications. The pectinolytic enzymes, responsible for cleaving both pectin and other pectic polysaccharides in galacturonic acid residues, have application in several sectors such as fruit and wine juice processing, recovery of essential oils, extraction of vegetable oils, as well as the textile and food industries.paper and cellulose. In this context, the aim of this work was to evaluate the production, stability and application of pectinolytic enzymes by Aspergillus niger IOC 4003 using acerola and cajá residues as solid state fermentation substrate (SSF). Initially, residues of acerola and cajá, washed and unwashed, were submitted to drying and determined their chemical and physicochemical composition. The percentage of calcium pectate, pectin indicator, found in residues was 3.46 ± 0.11%; 2.94 ± 0.18%; 5.85 ± 0.01% and 5.34 ± 0.23% for unwashed acerola, washed acerola, unwashed cajá and washed cajá, respectively. Then, the potential of these substrates as inductors for the production of pectinolytic enzymes by FES was evaluated during 240 h with initial pH of 4.5; humidity at 40% and spore concentration of 1 x 107 spores / mL. In the fermentation stage, the greatest polygalacturonase production was observed using washed cajá residue reaching enzymatic concentration of 38.22 ± 0.63 U / g in 72 h of cultivation. Next, the optimization of enzyme extraction was studied and the best condition of extraction occurred using contact time of 30 minutes and acetate buffer at concentration of 50 mM and pH 5.4. On subsequent step, the stability of enzyme complex was evaluated against temperature and pH. The best 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 cajá or unwashed acerola residue was applied in the process of clarifying cajá juice. In the clarification stage, the outcomes that stands out were 40% reduction in turbidity, 30% of clarification and 85% increasing of antioxidant capacity of the juice. In this way, the present work demonstrates the feasibility of using fruit industry residues as substrates for production of interest enzymes and its application in food industry.