Wine quality improvement through the combined utilisation of yeast hulls and Candida zemplinina/Saccharomyces cerevisiae mixed starter cultures

Background and Aims:Interactions between different yeast species used as starters may lead to inconsistent resultsin mixed fermentations. The aim of this study was to assess the influence of different nutrients on the associationbetween a wine strain ofCandida zemplinina(CDZ1) and a commercial wine strain ofSaccharomyces cerevisiae(EC1118)in mixed culture fermentations.Methods and Results:Laboratory-scale fermentations were carried out by inoculating CDZ1 and, after 3 days,EC1118 with the simultaneous addition of diammonium phosphate, yeast hulls, ergosterol and oleic acid, eachprovided separately. The addition of yeast hulls resulted in a higher cell population of CDZ1 and in a higher glycerolconcentration of wine as compared with that of the other fermentations. Pilot-scale fermentations, carried out in acommercial winery, confirmed that the winemaking protocol based on the use of the mixed starters CDZ1/EC1118with added yeast hulls results in wine with a higher glycerol content, more structured and persistent.Conclusions:Addition of yeast hulls improved the fermentative performance of the mixed starters CDZ1/EC1118.Significance of the Study:The high glycerol content of wines made with the combined use of yeast hulls andCDZ1/EC1118 mixed starters increases wine softness and body.