Radio carbon dating of TWAIOA

[winesecretary]

There are news reports that following an investigative study Dutch retailers have pulled some 10 & 20 year old TWAIOAs from the shelves over worries about how old they actually are. While no IVDP rules are being broken by selling wine younger than 10 years old as 10 year old TWAIOA, so long as it passes the tasting panel, I have been banging on for years about what I perceive to be a tension between IVDP rules and EU consumer protection law (and in particular Article 7(1)(a) and (b) of EU Regulation 2011/1169) in this regard.

[JacobH]

It’s a mess which, I think, the IVDP and Port industry just hopes will continue to slip under the radar. I’m not sure of another regulated wine or spirit where an indication of age on the bottle just means “it tastes like it is x years old”. I think in almost every region it means “each component is at least x years old” which is, of course, why a 20-year-old bottle of blended whisk(e)y is somewhat more valuable that an average 20-year-old tawny.

I could see an argument that the age should be the minimum average age of the contents of the bottle (which is what a lot of people say it represents), although this would, of course, be somewhat difficult to calculate.

I think the mistake was settling on age statements in the 1980s. A better solution would have been to do what Cognac did of giving the different categories names so that the minimum component age could be quite low without reducing the marketing potential. Indeed, I think this is what happened before the regulations restricted the categories of Port. You might sell your “reserve tawny”, “special reserve tawny”, “very old tawny” and a “rare v. very old tawny” or something as if they were the 10-, 20-, 30- and 40-year-old blends without making any misleading statements if you used to some younger components.

My impression is that the mess could be sorted out with the younger Ports, especially since how aged the components in a 10- or 20-year-old tawny taste is more dependant on how they have been matured rather than how long they have been matured: the younger components could be held for longer in tonnels / steel / concrete etc. I have no idea if that would be possible with the older ones, though, especially with the ever present issue of topping up.

Of course, the real place they ought to be concentrating is on the older colheitas. I have a feeling if they started to investigate those the whole game would start to come apart.

[winesecretary]

The situation with the IVBAM in Madeira is even worse than with the IVDP in Porto. It seems surprisingly easy to use a small amount of very old madeira to furbish up a blend that is mainly really quite young wine and persuade the IVBAM to pass it as 40 years old or whatever.

[JacobH]

Ah: should have realised that similar issues might also arise in Madeira. Are there similar issues with the grape varieties (e.g. can a single-varietal Madeira contain a proportion of other grapes)?

[Glenn E.]

Of course, the real place they ought to be concentrating is on the older colheitas. I have a feeling if they started to investigate those the whole game would start to come apart.

At the very least, that investigation might finally settle the "topping up" and "refreshing" discussion.

[uncle tom]

The bottom line is that this issue has the potential to throw up a very damaging scandal.

That port doesn't 'do' soleras is no justification for passing off some wines that appear to be essentially a solera as a dated colheita.

Carbon dating is real - and caused the 1970s alcohol scandal - we really don't need a re-run of that.

TWAIOA wines need to be based on average actual age - not 'perceived' age. I don't think that restriction would commercially impact the 10yr market and only marginally impact the 20yr, which between them make up the vast bulk of sales.

It would be senseless if a scandal involving the true average age of a 40yr were to mess up the entire market for them.

[Glenn E.]

There's also the problem that I don't trust carbon dating to be sufficiently accurate at this time scale with this product. The amount of atmospheric carbon that has been absorbed by a Port can presumably vary considerably based on storage conditions.

I would absolutely prefer for the number on the label to hold more meaning than it currently does, but I'm not sure that "average age" is the end goal. Which average age?

Whiskey's minimum age is probably better, though even then don't you run into potential problems when adding neutral spirit to get it within the legal limits? Maybe Cognac had it right all along.

It's a casual standard in Port already, but perhaps the "V" style mark is sufficient? Using that, a 20YO would become "Old Tawny Port", and 40YO would become "Very Old Tawny Port", and each subsequent "very" would add 20 years. The barrel marked "VVVV" at Barao de Vilar is, in fact, thought to be at least 100 years old. But that doesn't help with 10YO, 30YO, and 50YO.

[M.Charlton]

Whiskey's minimum age is probably better, though even then don't you run into potential problems when adding neutral spirit to get it within the legal limits?

It depends on the relevant regulations associated with the product in question. For instance, I’m a huge fan of the unambiguous provisions associated with whisky produced in Scotland, which in summary specify that:

“…the only age which may be stated in the labelling, packaging or advertising of a Scotch Whisky is the age of the youngest Scotch Whisky in the product.”

If the IVDP were to adopt the above language in their regulations, replacing “Scotch Whisky” for “Tawny Port”, it seems a lot of headache could be avoided with respect to the (minimum) age of the tawny being sold.

As for the practicalities on the production side (e.g., “refreshing” and “topping up”), that is, of course, another issue. However, such refreshing and topping up should, in principle, be governed by the above hypothetical regulation, in the same way Scottish whisky is at present.

[uncle tom]

There's also the problem that I don't trust carbon dating to be sufficiently accurate at this time scale with this product. The amount of atmospheric carbon that has been absorbed by a Port can presumably vary considerably based on storage conditions.

If the carbon date was derived from the sugars present in the wine, storage conditions should have no obvious impact. The percentage of Carbon 14 should be constant, irrespective of the concentration of the sugars, or its atmospheric exposure through the wood of a pipe..

..unless I'm missing something!

[Glenn E.]

There's also the problem that I don't trust carbon dating to be sufficiently accurate at this time scale with this product. The amount of atmospheric carbon that has been absorbed by a Port can presumably vary considerably based on storage conditions.

If the carbon date was derived from the sugars present in the wine, storage conditions should have no obvious impact. The percentage of Carbon 14 should be constant, irrespective of the concentration of the sugars, or its atmospheric exposure through the wood of a pipe..

..unless I'm missing something!

My understanding is that atmospheric Carbon 14 can be absorbed over time by products being tested, so the tester needs a complete history of the storage conditions in order to accurately determine the age. A product stored in an open vat, constantly exposed to air, would have a far different Carbon 14 dating result than the identical product stored in a hermetically sealed stainless steel tank. And all of the range in-between those two extremes.

Carbon 14 dating is quite accurate when conditions are known and constant. It gets suspiciously complicated when neither of those are reliable.

[akzy]

My understanding is that atmospheric Carbon 14 can be absorbed over time by products being tested, so the tester needs a complete history of the storage conditions in order to accurately determine the age. A product stored in an open vat, constantly exposed to air, would have a far different Carbon 14 dating result than the identical product stored in a hermetically sealed stainless steel tank. And all of the range in-between those two extremes.

Carbon 14 dating is quite accurate when conditions are known and constant. It gets suspiciously complicated when neither of those are reliable.

It should be relatively decent providing now much is being exchanged through the Cork. The carbon 14 is effectively ingested through the plant's life. Once it's dead, it doesn't take anymore in and the amount that's in it will start to decay at a well defined rate. No new carbon 14 should be added from other sources. Under 60 years cesium (thinks its this - certainly one nuclear weapons testing ingredient) dating can be used which adds another great data point.