engleski

Changes in the chemical composition of biologically treated grape pomace by Trametes versicolor under solid-state fermentation conditions

Biological treatment of grape pomace (GP) by Trametes versicolor TV6 was first investigated in laboratory jars, then the process was scaled up in a tray bioreactor. The aim of this work was to analyse the chemical composition of GP before and after the 15-day biological treatment, focusing on the profile of phenolic compounds. A reduction of total polyphenols, total flavonoids and total proanthocyanidins by 75%, 76% and 83% after treatment in laboratory jars and by 77%, 83% and 87% after treatment in a tray bioreactor was observed. Biological treatment had a positive effect on the recovery of individual phenolic compounds, increasing the extractability of 12 of the total 21 quantified phenolic compounds by 1.1- to 3.9-fold. Changes in the chemical composition of the lignocellulosic biomass were also evident in an increase in ash, protein, and fat content by 28%, 10%, and 17%, respectively, after treatment in laboratory jars and by 29%, 11%, and 7%, respectively, after treatment in a tray bioreactor. Hemicellulose content decreased, while lignin and cellulose content increased apparently due to degradation of readily available components. Of the hydrolytic enzymes measured, the highest activity was found for xylanase (346.04 U/gdb in laboratory jars and 200.65 U/gdb in a tray bioreactor) and of the lignolytic enzymes for laccase (2.67 U/gdb in laboratory jars and 0.96 U/gdb in a tray bioreactor).

grape pomace ; phenolic compounds ; biological treatment ; Trametes versicolor

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