Atypical Yeasts in WinemakingLinda F. BissonWine Flavor 101BMarch 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

10A 26AB 23AB 35B 26AB 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)