Atypical Yeasts in Winemaking Linda F. Bisson Wine Flavor 101B March 23, 2012

Grape and Wine Microbiota Diverse numbers of yeast and bacteria are found on grapes Persistence of microbiota depends upon: Relative numbers Permissive requirements for growth Presence of inhibitory conditions

Uses of Atypical Yeasts To complete fermentation (fructophilic Candida species) To add nuances: Metschnikowia, Torulaspora, Pichia

Experimental Goal We had a bad Chardonnay, low percentage of rot across most clusters A “true” native would be risky under these conditions Decided to assess impact of atypical yeasts under these high microbiota conditions

Two Types of Atypical Yeast Products Sequential Simultaneous

Sequential Products Inoculate first with non- Saccharomyces yeast At a specific later point in fermentation inoculate with Saccharomyces

Simultaneous Inoculation Products Inoculate once, with a specific mixture of non-Saccharomyces and Saccharomyces yeast Relative ratios impact persistence and duration of fermentation

Tested Three Different Yeasts with Sequential Addition FrootZen™: Pichia Metschnikowia MP346 Torulaspora delbrueckii

FrootZen™ Viniflora® FrootZen™ consists of the yeast Pichia kluyverii in frozen form Juice is inoculated with the Pichia strain, allowed to ferment to 4% v/v alcohol Then inoculate with Saccharomyces to complete fermentation

Informal Sensory: Sequential Students in class were able to differentiate all atypical yeast strains from native and inoculated fermentations post-fermentation Differentiation was statistically significant, with the Metschnikowia fermentations showing the least significant differences with both the native and inoculated fermentations

Initial Preference Ranking Yeasts & Rank Totals Native Pichia kluyveri Metschnikowia pulcherrima Torulaspora delbrueckii Saccharomyces cerevisiae Critical Value Difference Newell- MacFarlane 10 A 26 AB 23 AB 35 B 26 AB 18 Highest Score Means Most Preferred

Simultaneous Inoculation Products Based on adding specific mixtures of Kluyveromyces thermotolerans and Torulaspora delbrueckii Viniflora®: Harmony™ (Saccharomyces, Kluyveromyces, Torulaspora), Melody™ (Saccharomyces, Kluyveromyces, Torulaspora) and Rhythm™ (Saccharomyces and Kluyveromyces)

Fermentation Profiles

Conclusions No impacts on fermentation rate Rhythm™ was the only yeast that showed a significant difference from the Saccharomyces –only control

Atypical Yeast Tasting Glass 1: Saccharomyces control Glass 2: Native control Glass 3: Metschnikowia Glass 4: Pichia (FrootZen™) Glass 5: Torulaspora Glass 6: Rhythm™ (Kluyveromyces)