Obtenção de pectinases em cultivo submerso a partir de extratos aquosos de resíduos do processamento de maçãs

Abstract

Apple pomace is one of the by-products of the industrial extraction of juice from fruits. It is estimated that in 100 kg of processed apples, on average, 35 kg result in residues, being composed of seeds, peels and the pomace itself. In the composition of the apple pomace, soluble and insoluble substances are identified, such as saccharides and pectic substances, respectively. Pectinases are enzymes that catalyze the degradation of pectic substances present in plants, resulting in smaller molecules such as oligosaccharides and monosaccharides. These enzymes are produced via the fermentation route, mainly by fungi of the genus Aspergillus, being induced by the presence of pectic substances in the medium. Due to the high value of commercialized pectinases, it is necessary to search for alternatives to reduce the overall costs of the process. Among these bottlenecks, the use of natural inducers stands out, which would combine low cost and added value to agro-industrial waste, making the processing of apples and the production of pectinases more sustainable. In this form, the kinetics of the pectinase production were evaluated against the use of different residues from the processing of Gala and Fuji apples in submerged cultures of Aspergillus oryzae IPT-301. In the composition of the media, aqueous extracts referring to the two types of residues (apple pomace and apple seeds/peels) were used, with the addition of glucose and nutrient salts, and compared with the use of commercial pectin. Superior cell growth profiles were observed in media containing natural extracts, with biomass values of 17.2, 15.1 and 9.4 g/L for media containing extracts of seeds/peels, apple pomace and commercial pectin, respectively. Regarding the production of pectinases, the peak activity was reached in 96 hours, of 0.52 U/mL, with the use of residue composed of seeds/peels, while for the aqueous extract of apple pomace and commercial pectin, the maximum activities were 0.46 and 0.38 U/mL, in 120 hours, respectively. Residual values corresponding to non-fermentable sugars were quantified in all media, a characteristic aspect of media of high nutritional complexity. In general, the applicability of these aqueous extracts in the pectinase production process is highlighted as a way to promote circular energy and sustainable disposal of waste generated in fruit processing in Brazil, which meets the Sustainable Development Goals (SDGs), 2030 Agenda of the United Nations (UN). [resumo fornecido pelo autor]