ORIGINAL ARTICLE Valorization of mangaba residue (Hancornia speciosa Gomes) for polygalacturonase production from Aspergillus niger IOC 4003 and fabrication of active chitosan films Millena Cristiane de Medeiros Bezerra Jácome 1 & Carlos Eduardo de Araújo Padilha 1 & Murilo Ricardo do Nascimento Arrais 1 & Ana Laura Oliveira de Sá Leitão 1 & Francisco Canindé de Sousa Júnior 1,2 & Everaldo Silvino dos Santos 1 Received: 15 May 2020 /Revised: 24 September 2020 /Accepted: 22 October 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020 Abstract The present study proposes to obtain polygalacturonases, antioxidant compounds, and active chitosan films from a valorization scheme of mangaba residue. After extraction with ethanolic solution, the mangaba residue was used as a substrate for solid state fermentation (SSF) of Aspergillus niger IOC 4003, which obtained 76.32 U g -1 for polygalacturonase after 96 h cultivation. The previous step of solvent extraction increased the enzyme productivity and allowed the production of pH-tolerant polygalacturonase in SSF experiments. The addition of polygalacturosanase under 1.0 U mL -1 enabled the reduction of turbidity (34%) and viscosity (11%) of mangaba juice compared to enzyme-free condition. Solid residue from the SSF step was used in the extraction of alkaline lignin with sodium hydroxide, which allowed the recovery of 21.82% of the initial Klason lignin content. Supplementation of chitosan films with ethanolic extract and 0.1% (w v -1 ) alkaline lignin changed the values of antioxidant activity (increase of 86.5% and 45.4%) and permeability (reduction of 43.2% and 2.3%). Keywords Solid state fermentation . Juice treatment . Antioxidant activity . Fractionation . Lignin 1 Introduction The mangaba (Hancornia speciosa Gomes) is an exotic fruit from Cerrado and Restinga vegetations of Northeast Brazil [1]. It is a berry-type fruit and has a yellowish red color, intense aroma, and sweet flavor when ripe [1, 2]. Mangaba can be eaten fresh, but it is often consumed in processed form like juices, cookies, jams, and ice cream [3]. According to Perfeito et al. [4], the food industry generates 33% of the initial mass of the fruit as depulping residue, which is often discarded in landfills. To minimize the environmental impact of this disposal, proposals for the valorization of mangaba residue are urgent. The consolidation of the biorefinery concept has promoted changes in the management of fruit residues in order to pro- duce biofuels, materials, and chemicals [5]. In general, fruit residues are sources of bioactive compounds such as phenolic compounds, polyphenols, carotenoids, and fat-soluble vita- mins, which confer a series of benefits to human health [6]. Diets rich in natural bioactive compounds are correlated to the prevention of cardiovascular and neurodegenerative diseases [7]. Like other agro-industrial residues, fruit residues are recog- nized as lignin sources. After cellulose, lignin is considered the second most abundant biopolymer on the planet and it is found associated with cellulose and hemicellulose in the plant cell walls [8]. Lignin is synthesized by plants from the poly- merization of coniferyl, sinapyl, and p-coumaryl alcohols [9]. Paper and cellulose industries use lignin to produce heat and electricity due to their high calorific value [9, 10]. However, the recent literature has reported noble applications of lignin, which include the synthesis of biofuels [11], polyurethane Supplementary Information The online version contains supplementary material available at https://doi.org/10.1007/s13399-020- 01102-4. * Everaldo Silvino dos Santos everaldo@eq.ufrn.br 1 Laboratory of Biochemical Engineering, Chemical Engineering Department, Federal University of Rio Grande do Norte (UFRN), Natal, RN, Brazil 2 Laboratory of Bromatology, Department of Pharmacy, Federal University of Rio Grande do Norte (UFRN), Natal, RN, Brazil Biomass Conversion and Biorefinery https://doi.org/10.1007/s13399-020-01102-4