Can science prove wine provenance?

Dr Eric Wilkes jokes that people have been seeking a silver bullet for proving wine provenance ‘forever’.

It’s only really been scientifically feasible for the past 35-40 years, but his comment sums up the complexity of the task.

A new project at the Australian Wine Research Institute (AWRI) led by Research Scientist Dr Martin Day is looking to determine whether by combining the right mix of parameters it is possible to prove with sufficient certainty where a wine did – or in some cases didn’t – come from.

‘There are two parts to this issue’, said Dr Wilkes, the AWRI’s Group Manager, Commercial Services. ‘If you want to know whether a wine is the specific wine it claims to be be, that is a simple task. We can just get a bottle we know to be genuine and compare the two chemically in a day or so.

‘The bigger challenge is to verify a claim that a wine is, say, Australian in origin. We have an idea in our head what that means, but chemically it’s not as well defined because it depends on where the fruit came from, how the winemaker made it, what vintage was like etc.’

Dr Day said there were two broad groups of factors with the potential to provide the right evidence: what comes from the soil and what comes from the environment – sunlight, rainfall, distance from the sea and height above sea level among them.

To date most research, primarily in Europe, has focused on examining one type of data at a time to see if it can provide a clue. Dr Day’s approach is to bring together two or more unrelated data sets to see if they can provide a clearer picture. A pilot trial last year analysed 250 samples with promising results, providing the impetus for a larger project funded by Wine Australia.

There are a number of complexities to the task, beyond the pure science. Not the least of these is that the winemaking process can affect how certain elements appear, if at all, in finished wine.

‘A really important aspect that an organisation like the AWRI brings to this is our training in oenology’, Dr Wilkes said. ‘You need to understand the science in the winemaking context or you could make incorrect assumptions and thus incorrect decisions.’

An important point here is that if the winemaking process can change how things present themselves in the wine, then it might be possible for people to modify a given wine to make it appear as if it came from somewhere else.

‘In Europe there’s a lot of secrecy around the data produced for those reasons – so you can’t actually confect something to look like something else’, Dr Day said. ‘Wine counterfeiters are always aiming to be one step ahead of the people trying to catch them.’

Both Dr Day and Dr Wilkes are involved with working groups trying to set some internationally recognised parameters around how databases are developed and on what basis one country should be able to make decisions about wines from another country. Some scientific questions are still being challenged.

The reality, of course, is that Dr Day’s research may come to the conclusion that there is no combination of parameters, no matter how complex and comprehensive, that can identify a wine’s origins with the certainty required in all circumstances.

Dr Wilkes compares it to ‘some of the things happening with DNA evidence’. How sure do you need to be in certain circumstances? Sometimes 95 per cent may be good enough, but in others only 99+ per cent will do.

‘We have a range of target compounds that we are confident are going to advance our knowledge’, he said. ‘At the end of the process, when we know what our level of confidence is, that will determine where we go next.’