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Background and Aims Interactions between different yeast species used as starters may lead to inconsistent results in mixed fermentations. The aim of this study was to assess the influence of different nutrients on the association between a wine strain of C andida zemplinina ( CDZ1) and a commercial wine strain of S accharomyces 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, each provided separately. The addition of yeast hulls resulted in a higher cell population of CDZ1 and in a higher glycerol concentration of wine as compared with that of the other fermentations. Pilot-scale fermentations, carried out in a commercial winery, confirmed that the winemaking protocol based on the use of the mixed starters CDZ1/ EC1118 with 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 and CDZ1/ EC1118 mixed starters increases wine softness and body. [ABSTRACT FROM AUTHOR]

Aim: To verify a possible correlation between cell lipid composition, expression of key genes in lipid metabolism and fermentative behaviour of Saccharomyces cerevisiae wine strains. Methods and Results: The fermentative abilities of two commercial wine strains of S. cerevisiae were tested under stressful conditions. Cell number, glucose and fructose concentrations, expression of ACS1, ACS2, ACC1, OLE1, ERG9, ERG10, ARE1 and ARE2 and lipid content were evaluated. The strain that failed to complete the fermentation had lower amounts of C16:1 and C16:0 fatty acids at the beginning of fermentation (0 h) and late logarithmic phase (72 h). While the amount of C18:1 in this strain was lower than that in the strain that completed the fermentation at 0 h, same levels were observed for both strains at 72 h. The sterol levels were generally higher in the strain that failed to complete the fermentation. Gene expression generally increased from the beginning of the fermentation to the late logarithmic phase in both strains. Conclusion: A positive correlation between good fermentative ability, elevated fatty acid content and ACC1 gene expression has been identified. Significance and Impact of the Study: The cell lipid content at the time of inoculum and expression of ACC1 gene of starter strains should be carefully considered in order to identify the possible stuck/sluggish fermentations. [ABSTRACT FROM AUTHOR]

In this study, three flor strains of Saccharomyces cerevisiae were genetically characterized. They were isolated from biofilms on Sardinian sherry-like wines produced at family-run wineries where pure cultures of yeasts were not used. The study aimed to investigate the life cycle of these naturally-occurring flor strains, using a genetic procedure supplemented by analysis of subsequent meiotic generations. A semi-homothallic life cycle was found in three strains that could be helpful in a genetic improvement programme. [ABSTRACT FROM AUTHOR]