‘The alcoholic content of wine has gradually risen from 12-12.5 per cent to beyond 15 per cent in last couple of decades. The boost in alcohol content reduces aroma and flavour intensity of the wine. It compromises wine quality, including increasing the perception of hotness, body and viscosity and to a lesser extent, sweetness and acidity,’ according to researchers at the Australian Wine Research Institute.
Besides the issues of public health due to higher alcohol consumption, there are some countries where taxes are based on alcohol content and there is thus a need to find solution for reducing the alcohol content.
The researchers experimented to study the effect of different type of yeasts on reducing alcohol levels. They made wines from Shiraz and Chardonnay with over 50 different types of yeast in hopes of finding some strains that would convert sugar into products other than ethanol without severely changing the flavour and aroma characters.
The Australian team added a combination of two types of yeast (Metschnikowia pulcherrima and Saccharomyces cerivisiae) to unfinished wine mixes, which successfully reduced the alcoholic content in Shiraz from 15 percent to 13.4 percent without changing the flavour. The scientists concede it may not be a huge change, but it might suffice to keep at bay the changes global warming is causing in the alcohol levels, at least for a few years. The process worked well with many grapes but not too well with Chardonnay. The alternative yeasts created side products that reduced the quality of the wine.
Interestingly, Uma and Krishna Prasad the marathon wine couple owning KRSMA Estate Wines, tending to the vine and totally immersed in making wine in the Hampi Hills in Karnataka are also currently working with a special yeast given by the French yeast company Laffort which has selected one winery in each country it is dealing with for the experiment. The objective is how to get most flavours though not specifically on reducing the alcohol content.
Krishna Prasad, who cherishes assistance from AWRI towards the production of KRSMA wines being launched on February 1 in Bangalore, says ‘I am very impressed with what AWRI is doing. This is just one of their achievements and should help understanding the yeast vs. wine flavours and alcohol substantially.’ KRSMA wines are currently not very high in alcohol with the usual range being 12.5-13.5%. His interest lies more on getting the best flavours and aromatic profile.
Global warming, which is hitting Europe as well has made the concern even bigger now. There have been some studies in the past involving genetically modified yeasts with the same objective of reducing the alcohol content, but the attitude toward genetic modified yeasts in Europe is absolutely negative, says Gaia Gaja, daughter of the iconic producer Angelo Gaja, who has been gradually taking over the wine making and marketing performed by him in the past.
‘This Is the first time I read about this study you mention, and I think it’s an experimentation that still has to be finalized not only in laboratories but most of all in cellars , which is very different. At the moment we need to understand more. Research should continue; it has to be tested if the process in laboratory is replicable in the cellar as well where yeasts producing alcohol are not only those on the skin of grapes, but also those living in the cellar itself: it is not that obvious which group of yeasts prevail on the other,’ she asserts.
‘Surely to reduce alcohol lever all the existing processes are so far largely manipulative (reverse osmosis for example) and research has to continue in the direction of more natural remedies,’ she adds.
Piemonte has been one of the more fortunate regions that have not been harmed significantly by global warming because of it being in the cooler parts. ‘For Nebbiolo global warming has rewarded a complete ripeness but wines more often reach 14.5° alcohol. This is already a high limit but we are not facing 16 or 17 degrees as more often happens in the new world,’ she feels.
As the report in motherboard suggests, unless warming can be stopped or slowed down, continued band-aid solutions provided by a study like this, might be the best that some vineyards can hope for.
The research appears in the journal Applied and Environmental Microbiology published by American Society for Microbiology (ASM).