Effect of Candida zemplinina oak chips biofilm on wine aroma profile

Candida zemplinina (synonym Starmerella bacillaris) is frequently isolated in grape must in different vitivinicultural areas. The enological significance of C. zemplinina strains used in combination with S. cerevisiae has been demonstrated, being wines produced by the above-mixed starter, characterized by higher amounts of glycerol and esters. The ability of this species to compete in a harsh environment such as wine is due to elaborate survival strategies. Biofilm formation is the principal way of resisting environmental stresses and represent the main microbial lifestyle in natural niches. Therefore, in this study 10 strains of C. zemplinina were analyzed to assess cell surface hydrophobicity using microbial adhesion to solvents (MATS) test and tested for their ability to form biofilms on winemaking material such as stainless steel and oak chips. The contribution of C. zemplinina biofilm on this material to wine aroma was evaluated. All strains showed a certain degree of hydrophobicity, and adhered to tested surfaces. In particular, sessile cells on chips ranged from 4.3 Log CFU/mL to 6 Log CFU/mL, while on stainless steel from 2.6 CFU/mL to 4.2 CFU/mL. Solid-phase microextraction gas chromatography-mass spectrometry showed that biofilm developed on oak can modulate the wood-wine transfer of volatile aromatic compounds. Therefore, surface-associated behaviours should be considered in the development of improved strategies to shape aroma profile of wines.