We investigated the enzymatic complex produced by selected fungi strains isolated from the environment using the agro-industrial residues rice husk, soybean hull, and spent malt as substrates. Microbial growth was carried out in solid-state cultivation (SSC) and in submerged cultivations (SC) and the enzymatic activities of xylanase, cellulase, β-xylosidase, and β-glucosidase were determined. All substrates were effective in inducing enzymatic activities, with one strain of Aspergillus brasiliensis BLf1 showing maximum activities for all enzymes, except for cellulases. Using this fungus, the enzymatic activities of xylanase, cellulase, and β-glucosidase were generally higher in SSC compared to SC, producing maxima activities of 120.5, 25.3 and 47.4 U g of dry substrate, respectively. β-xylosidase activity of 28.1 U g of dry substrate was highest in SC. Experimental design was carried out to optimize xylanase activity by A. brasiliensis BLf1 in SSC using rice husk as substrate, producing maximum xylanase activity 183.5 U g dry substrate, and xylooligosaccharides were produced and characterized. These results suggest A. brasiliensis BLf1 can be used to produce important lytic enzymes to be applied in the preparation of xylooligosaccharides.
Summary
We investigated the simultaneous production of xylanase and the liberation of xylooligosaccharides in rice husk solid‐state cultivations of Aspergillus brasiliensis BLf1 and by the recombinant Aspergillus nidulans XynC A773 strain. The bioprocess was optimised by experimental fractional design and response surface analysis. Results show that both fungi strains produced xylanases and their activities were dependent on the addition of basal medium, moisture content and the interactions between particle size and inoculum size, producing maximum xylanase activities of 230.7 U g−1 substrate for A. brasiliensis, and 187.9 U g−1 substrate for A. nidulans XynC. Xylooligosaccharides were liberated in the same cultures, with concentrations up to 17.6 mg g−1 and 23.9 mg g−1 of substrate for A. brasiliensis and A. nidulans XynC, respectively, both strains presenting similar profiles, with xylose residues varying from X3 to X6. These results suggest the possibility of lowering production costs of enzymes for food applications and oligosaccharides.
The aim of this study was to evaluate the properties of nanocomposite films of protein isolates from mechanically deboned chicken meat with organoclay (montmorillonite). For the film development, a 2 3 experimental design was performed with three levels, protein isolate (2, 3.5, 5 g.100 mL-1 of solution), montmorillonite (0.3, 0.5, 0.7 g.100mL-1 of solution) and glycerol (25, 30, 35 g.100 mL-1 CPI). The tensile strength varied between 6.7 and 9.1 MPa, elongation to break from 26-66%, opacity of 13.1 to 35.7 and solubility from 38.5% to 81.8%. Assessing the structural properties, interleaving of the isolate and montmorillonite can be noted. The results obtained in the experimental design indicate that 2.0 g of CPI.100 g-1 of solution, 0.8 g of MMT.100 g-1 of solution and 0.2 g of glicerol.100 g-1 CPI are the ideal parameters for preparing nanocomposite films.
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