Effect of isomixing on grape must fermentations of ATF1–overexpressing wine yeast strains

Niël van Wyk*, Florian Michling, Dennis Bergamo, Sylvia Brezina, Isak S. Pretorius, Christian von Wallbrunn, Jürgen Wendland

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

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Speeding up grape must fermentation would be of great economic benefit. We subjected Saccharomyces cerevisiae VIN13 and two recombinant VIN13-strains expressing ATF1 alleles under two different promoters (either PGK1 or HXT7) to four styles of grape must fermentations; we then assessed the effect of constantly stirring a must fermentation (isomixing). The four different fermentation setups were as follows: isomixed, closed in an ANKOM Rf Gas productions system; isomixed, open in a stirred tall tube cylinder; static, closed constituting a conventional fermentation in a wine bottle equipped with an airlock and static; and static, open in a tall tube cylinder (without stirring). We report on major fermentation parameters and the volatile aroma compositions generated in the finished wines. The primary fermentations of the strains subjected to constant stirring finished after 7 days, whereas the static fermentations reached dryness after 19 days. The wines derived from isomixed fermentations produced approximately 0.7% less ethanol compared to the unstirred fermentations. The speed that the isomixed fermentation took to reach completion may provide an alternative to static fermentations in the preparation of base wines for sparkling wine production. The observed increase of volatiles of isomixed fermentations merits further investigation.

Original languageEnglish
Article number717
Number of pages14
Issue number6
Publication statusPublished - Jun 2020

Bibliographical note

Copyright the Author(s) 2020. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.


  • Alcohol acetyl transferase
  • Isomixing
  • Microvinification
  • Recombination
  • Saccharomyces cerevisiae
  • Wine yeast

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