The effect of fungal proteolytic enzymes on myofibrillar proteins in dry-aged beef

The role of fungi in traditional food fermentation is not fully understood. The aim of this study was to assess the enzymatic potential of a fungal biostarter isolated from dry-aged beef. We have applied a multi-omics approach, i.e. combined the analysis of genomic and transcriptomic data with the observation of protein degradation patterns in the fungus-inoculated meat. Thanks to this, it was possible to pinpoint the enzymes produced by the fungus responsible for the changes occurring during dry-ageing. By comparing samples of meat inoculated with the fungal biostarter and those without, we were able to establish the effect of fungal enzymes on meat protein composition. The presence of the fungus on meat increased the relative amount of selected low-molecular-weight proteins (i.e.113.9 kDa, 103.5 kDa, and 18.9 kDa). We believe this change may be caused by fungal endopeptidase activity. Additionally, results of transcriptome analysis indicate that several aspartic endopeptidases were expressed by the fungus. The identified enzymes have a similar structure to the aspartic peptidases used as microbial rennets. Overall, the changes caused by the fungus during dry-ageing seem to be linked to the activity of released aspartic endopeptidases.