The Devil’s Triangle – closer to home than you thought

There’s just something about the Bermuda Triangle that has always fascinated me. This mythical stretch of ocean is also called The Devil’s Triangle by many superstitious sailors and pilots. As a young boy I remember reading a novel about ships sinking under mysterious circumstances, navigation systems on ships and airplanes alike going awry, compass needles spinning like tops, and even sightings of ghost ships – all of this happening in the wretched Bermuda Triangle.

In wine there can also exist a Devil’s Triangle situation, where pH values do the unexpected, TA measurements plummet or skyrocket, and laboratory equipment seemingly taps out, unable to provide sensible chemical analysis.

Wine chemistry can be treacherous

OK, I’m overdramatising, but I want to make a point. Just like the Devil’s Triangle, in winemaking chemistry you will have three points, or vertices to the geometry whizzes. The three vertices being pH, TA, and a third factor. One example could be an external factor such as climate change, where heatwaves can have a dramatic effect on juice pH and TA. Think of a 4 x 4 wine, where the pH and TA values are both close to four due to lower levels of mostly tartaric and malic acid. Untreated, such a wine will be characterless and flat, lacking in mouthfeel and vibrance. It will also be microbially at risk and there will be limited ageing potential.

Another ominous third point to the wine chemistry triangle could be when Bordeaux comes to the South African winelands – also a weather-driven phenomenon. A winemaker jokingly told me that the last part of the past harvest was like a typical Bordeaux harvest, with intermittent rain causing wildly fluctuating ripeness levels, phenolic immaturity in some cases, and widespread rot.

A little rot can go a long way

One of the many problems with rot, driven by a variety of microbial scoundrels, is the nasty organic acids and other unwanted organic characters that are produced. We’re all quite familiar with laccase and elevated protein levels by now – click here to read a previous blog I wrote on the subject. As for organic acids, the two main culprits are acetic acid (which falls under the VA umbrella) and the lesser known gluconic acid.

While gluconic acid (pKa = 3.86) is a relatively weak acid compared to tartaric acid (pKa = 2.98), I don’t want to focus that much on what gluconic acid does in wine. Let’s rather look at how it can be detected, what its presence implies in terms of wine quality, and what can be done about it.

Wine made with fruit unaffected by rot will have about 0.5 g/L gluconic acid, whereas fruit affected by noble rot or sour rot will have levels ranging from 1 to 5 g/L. So how do you detect gluconic acid? You check for it yourself, of course! We now stock Vintessential enzymatic test kits which offer you speedy analysis and the convenience of doing a variety of chemical analysis, including D-gluconic acid, in your cellar. To read more about these super handy test kits, click here, or contact us directly for a demo.

The acid balancing act in wine

It should be noted that significant changes in must organic acid levels occur as a result of rot. The metabolization of tartaric- and malic acid can cause an increase in pH and a decrease in TA, a situation that is best avoided. So, what to do?

Apart from following our rot protocol (have you clicked on that blog link that appeared earlier yet?), how about thinking a bit further than just adding boring old tartaric acid to wine? Consider the use of ZYMAFLORE® OMEGA^LT. This yeast can produce super high levels of lactic acid and will give your flabby wine a serious kick in the rear end in terms of pH, TA, and freshness. And yet another option, instead of adding tartaric acid to wine, is FUMARIC^trl. Fumaric acid (pKa = 3.03) is an organic acid which can be used to stop or inhibit MLF, and in wines where little or no sulphur dioxide is used. Note that the legislation on fumaric acid use is bound to change soon, so watch this space.

The next time the chemical analysis of your wine seems a little off, consider reaching out to us. And be glad you’re not stuck on a boat somewhere in the notorious Bermuda Triangle with a bunch of superstitious seamen.