engleski

Biological treatment of sugar beet pulp for the possible use in lignocellulosic biorefineries

The economic value and valorisation of food and agro-industrial residues or by-products in general, can be enhanced through an integrated biorefinery approach by producing second-generation biofuels together with value-added products, chemicals or materials. In this work, sugar beet pulp was used as a substrate for the cultivation of Trametes versicolor TV6 under solid-state fermentation (SSF) conditions. The main purpose was (a) to produce an enzyme cocktail rich in hydrolytic and lignolytic enzymes for possible further application in various industrially important biotransformations ; (b) to produce sugar hydrolysate for possible application in biofuel production ; (c) to analyse the possibility of using the solid residue, remaining after biological treatment, for feed production. The enzyme cocktail produced after 15 days of fermentation consisted of the following enzymes with corresponding activities: xylanase (V.A. = 198.92 U/mL), invertase (V.A. = 16.77 U/mL), cellulase (V.A. = 0.04 FPU/mL), β-glucosidase (V.A. = 3.02 U/mL), and laccase (V.A. = 0.04 U/mL). Total sugar concentration increased 25.3-fold during the 15 days, reaching value of 89.73 mgglucose/gdb. Crude protein content increased from 11.25 %db to 13.23 %db, as did ash content, which increased 2.2 fold, from 3.89 %db to 8.68 %db. Among dietary fibres, hemicellulose degradation was the highest, decreasing from 26.53 %db to 10.09 %db, followed by cellulose, which decreased from 25.92 %db to 21.43 %db. Finally, the quality and health safety of sugar beet pulp was evaluated before and after treatment. Solid-state fermentation resulted in a shift in nutrient parameters toward higher gross energy content, lactic acid content, and mineral content. The acetic acid content decreased in the biologically treated samples, while at the same time the content of lactic acid increased by 35 %. The concentration of various mycotoxins as well as polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) and their concentrations either remained unchanged or even decreased after SSF, as did the concentrations of PAHs.

sugar beet pulp ; biorefineries

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