The quest to find effective ways to produce lower alcohol wines has become so important that the University of Adelaide established a research centre just to focus on it.
The first Australian Research Council Training Centre for Innovative Wine Production (ARC TC-IWP) brought together 18 or so individual projects with the aim of taking a whole-of-production-chain approach to testing the range of known options for controlling the development of alcohol.
‘We came at it from the point of view that while you can tweak alcohol and flavour, particularly alcohol, in a number of ways – typically in single steps such as distillation or harvesting the fruit early – they tend to have negative side effects on flavour’, said the Centre’s Director, Professor Vladimir Jiranek.
‘Rather than attack the problem at just one or two points, we thought to actually look at ways we can control alcohol and flavour at many points through the process, so collectively we’d achieve significant alcohol reduction but without the trade-offs.’
The goal is to find one or more combinations of strategies that will give winemakers the ability to control alcohol levels without being too expensive, too difficult or too disruptive. ‘We are conscious that vintage is not a time when winemakers want to do additional treatments, they want to do fewer’, Prof Jiranek said.
Over the three years of the project, a team of PhD students and postdoctoral researchers undertook specific individual projects chosen in consultation with an overall project co-ordinator (a new role funded by Wine Australia) to ensure they all sat well within an integrated strategy.
‘Even simple things like using the same resources was important’, Jiranek said. ‘A student doing the early harvest work would pass fruit on to a student studying different yeast strains, then the same wine was dealt with by a student looking at using additives to modulate flavour and mouth feel, and so on down the chain. In the end we had wine that had been subjected to three, four or more treatments.’
There were eight key project areas, ranging from fundamental research into grape berry cell death and the importance of the sugar-potassium nexus to studies of the value of early harvest and blending regimes, yeast selection and the use of winemaking techniques for alcohol management and flavour enhancement.
Jiranek says some important progress was made in each of these areas (you can read the final report here) as well as in validating the value of a whole-of-production-chain approach.
‘We only had three years, but what was revealed was that certainly a combination of treatments gives you a better outcome than a single step.
‘As is the case with many winemaking treatments, it depends on many variables and there are a lot of caveats around it, but if you do use multiple steps you tend to get a much more complex, more rounded end product than if you just go in with a single step.’
The researchers were particularly surprised by how impactful some yeasts could be in lowering ethanol in wines without decreasing – and in some cases increasing – wine quality.
‘For the first time we evaluated some non-Saccharomyces yeasts already on the market that are largely promoted for sensory and mouthfeel type effects. No-one had previously looked at them side by side under the same conditions to see how they compare in terms of things like fermentation performance and ethanol yield.’
The quest for knowledge will continue, but now as part of an expanded research program. The ARC TC-IWP, which was formally launched earlier this month after receiving new funding from the ARC, will tackle a broad range of issues around wine sector efficiency, productivity and challenges from pests/disease, spoilage and the environment.
‘Some of these are long-standing problems; we are looking at ways we can tackle them and get integration across many projects’, Jiranek said.