FROM CITRUS WASTE TO BIOACTIVE COMPOUNDS

DIAZ GV; CONIGLIO,R.O.; ORTELLADO, LAURA E; ZAPATA, PD.,; FONSECA, MI.

Congreso; XVIII Congreso de la Sociedad Argentina de Microbiologia General SAMIGE; 2023

Agricultural industries are searching for biotechnological solutions to address waste management, an environmental issue that is of great importance and constitutes a significant challenge. It is even more relevant considering the circular economy approach since these secondary by-products can generate compounds with added value.The objective of this work was to obtain bioactive compounds from citrus residues using a homemade enzyme cocktail of Aspergillus niger LBM 134. For this, a Czapek liquid culture medium supplemented with sugarcane bagasse, 15 g L-1 was inoculated with a spore suspension of 107 mL−1 spores of the fungus. The enzymes present in the cocktail obtained were evaluated.Using this enzymatic cocktail, enzyme-assisted extraction (EAE) tests of bioactive compounds from citrus residues, specifically orange peels, were carried out. The conditions of temperature, pH, and extraction time were optimized using a five-level central composite design.In addition, four control groups were carried out to evaluate the performance of the A. niger LBM 134 enzyme cocktail on the extraction of phenolic compounds. The first control group was a conventional alkaline extraction (AE) using 1 N NaOH pH 9.5. The second set was a buffer-assisted extraction using only 0.05 M sodium acetate buffer, pH 4.8; the third group was EAE using the A. niger enzyme cocktail LBM 134 pretreated at 100 °C for 5 min; and the fourth group was an EAE using 10 IU of the commercial enzyme Viscozyme L (Novozymes, Denmark).After extraction, the supernatants were obtained, in which the total phenol content (CFT) was determined using the Folin/Ciocalteu method and expressed in mg equivalents of gallic acid mL-1 against a standard curve. The optimal extraction conditions were at 40 °C, pH 5, and 8 h.The greatest release of phenolic compounds from citrus residues was obtained with the enzyme-assisted technique using the A. niger LBM 134 enzyme cocktail (P < 0.05). These trials yielded 112% and 30% more phenolics than conventional and commercial alkaline enzymatic extraction methods, respectively.Subsequently, an analysis of the compounds present in the supernatants was performed by LC-MS/MS analysis. The following compounds were identified: tryptophan, hesperetin, and ρ-coumaric and quinic acids in the enzymatic extractions and gallic acid in the alkaline extractions.The compounds were successfully obtained by enzyme-assisted extraction from citrus residues using an enzyme cocktail produced with A. niger LBM 134 using raw sugarcane bagasse as a substrate, which increased the ecological sustainability and profitability of the bioprocess.