Now, special yeast to preserve flavour of wine

Researchers have identified special yeast that reduce the alcohol content in wine, helping to preserve the flavour of the beverage.
According to researchers, the alcoholic content of wine has gradually risen from 12-12.5 per cent to beyond 15 per cent in last 10-15 years.
The boost in alcohol content reduces aroma and flavour intensity of the wine, they said.
This, plus issues of public health, as well as taxes (in some countries, on alcoholic content), have created a need for approaches to lowering alcohol content, researchers said.
The new study began with a systematic screening of non-Saccharomyces yeast as a means of achieving such a reduction, said corresponding author Cristian Varela of the Australian Wine Research Institute, Adelaide, South Australia.

The investigators evaluated 50 different isolates from 40 species and 24 genera for their capacity to produced wine with reduced ethanol concentration.

They chose the most successful of these yeasts, Metschnikowia pulcherrima AWRI1149, for experiments in which it was set to work separately on Chardonnay and Shiraz musts.
Once the slower-growing Metschnikowia yeasts had consumed 50 per cent of the sugar, S cerevisiae were added to the mix to complete the process.
This "sequential inoculation" reduced the alcohol content in Shiraz from 15 per cent to 13.4 per cent (and somewhat less in Chardonnay).
Controls not inoculated with non-Saccharomyces strains did not produce reduced alcohol content, according to the report.

"The reduction isn't all that great, but it's in the right direction, and with more work, they might get that even lower, perhaps by letting the non-Saccharomyces yeast go longer before you throw in the Saccharomyces, said Alan Bakalinsky, of Oregon State University, Corvallis, who was not involved in the research.
The research appears in the journal Applied and Environmental Microbiology published by American Society for Microbiology (ASM).