Screening of fungi from the phylum Basidiomycota for degradation of boar taint aroma compounds

Wood-degrading fungi and enzyme preparations derived thereof were identified to degrade boar taint compounds. Fungal strains (n = 27) were analytically and sensorially screened for skatole (SK) and androstenone (AEON) degradation in head space (HS) vials and agar plates, respectively. Eight strains were able to reduce > 80% of AEON and > 80% of SK intensities. Three enzyme fractions (extracellular, intracellular, and mycelial) obtained from submerged cultures of Cerrena zonata, Irpex lacteus, Marasmius cohortalis (MCO), and Trametes hirsuta were used for SK and AEON bioconversion. Several enzyme fractions were able to reduce 90-100% of SK/AEON concentrations in the reaction mixtures based on the volatile analysis. MCO extracellular enzyme fractions (EEF) and mycelial enzyme fractions (MEF) were able to completely abolish both compounds and were therefore used for a sensory 2-alternative forced choice discrimination test in parallel to quantitative analysis. HS-SPME-GC-MS results demonstrated that active EEF and active MEF reduced > 98% SK and AEON intensities individually and > 92% in the SK/AEON mixture. Discrimination tests with trained panelists revealed that samples were perceived significantly less intense regarding SK, AEON, and SK/AEON than the control samples with d' values (a discrimination value) of 1.19, 0.74, and 0.72 for active EEF and 2.12, 0.88, and 2.12 for active MEF respectively, which were well in line with the analytical results. This indicates that both fractions (EEF and MEF) were effective in the boar taint reduction in aqueous solutions. The study revealed that Basidiomycota or enzymes derived thereof may become interesting tools to remove boar taint compounds.

Automated summary

Wood-degrading fungi and enzyme preparations derived thereof have been identified as effective tools for degrading boar taint compounds and reducing their intensity in aqueous solutions.