Evidence of gushing induction by Penicillium oxalicum proteins.

AIMS: The aim of this study was to elucidate whether grape-associated fungi exert an influence on gushing by their production of surface-active compounds.

METHODS AND RESULTS: In preliminary experiments, 58 grape-associated isolates of species within Penicillium and Aspergillus genera were tested for their ability to modify the surface activity of culture supernatants. As the genus Penicillium had a higher potential to change surface activity, further research focused on that genus. Subsequently, supernatants of 36 Penicillium isolates were assessed for their potential to induce gushing in a model system. Isolates of Penicillium oxalicum had the highest potential. Different external factors were investigated for their influence on the intensity of gushing. By using reversed-phase high performance liquid chromatography and subsequent MALDI-TOF MS, SDS-PAGE and nano-ESI-LC-MS/MS analysis, two proteins in the exoproteome of P. oxalicum were identified, which could be linked to the induction of gushing.

CONCLUSIONS: Our results suggest that infection of grapes by P. oxalicum may contribute to gushing in sparkling wine.

SIGNIFICANCE AND IMPACT OF THE STUDY: In contrast to gushing of beer, the reason for its development in sparkling wine is widely unexplored. Nonetheless, sparkling wine producers have also been affected by this economically damaging phenomenon. This study has first suggested about the occurrence of primary gushing in sparkling wine.