Colloids and the winemaker – stable relationship or uneasy truce?

I read with great interest about the decimation of Australian wine exports to China during and after the Covid-19 pandemic. This article (click here to read it) describes how the once flourishing trade sharply dropped from 121 million to 1.4 million litres, a decline of 119.6 million litres, and its subsequent recovery after China lifted its punitive tariffs.

I’m sure that quite a few Ozzy wine producers remain rather uneasy after realising how fleeting and unstable trade relations between countries can be. France and Chilli have gained considerable market share in Australia’s absence, but be sure that there exists and uneasy truce between all the countries involved.

Colloids love to mingle

Speaking of uneasy truces and instability, wine stability is a concept that many winemakers are also wary of. While a lot can be done right before bottling (or boxing or canning or any relevant verb ending with ‘-ing’) to improve a wine’s colloidal stability, in many cases the winemaker’s actions during the earlier phases of a wine’s lifetime, red wine in particular, play a major role in how those colloids will mingle and (possibly) misbehave later on. Or interact, for the geeks out there.  

Notably, the three groups of compounds most of us will think about when there is talk about colloids are proteins, potassium bitartrate and polyphenols, which respectively influence protein stability, cold stability and colour stability. In this blog I’m going to focus on the last two types of stabilities, but you are welcome to read more about protein stability in my previous blog post titled ‘Is protein stability wine’s holy grail?’.

On pHining, pH and the pHuture (opH a red wine)

From the above caption, the astute reader will surmise that pH remains king when it comes to wine quality. We know that lower pH values improve stability, and it is generally accepted that a pH in the range of 3 to 3.5 is much more desirable than a pH of, say 4. And going a bit further, a more stable wine is also a more ageable wine.

To really drill in the importance of pH management in winemaking, realise that it plays a role in a slew of really important stuff that happens in a wine. What stuff, you ask? Well, how about microbial stability, the solubility of tartrate salts and proteins, the effectiveness of free sulphur dioxide, enzymes and bentonite, colour stability, and finally oxidative and browning phenomena. Click here to read a very interesting article on acidity and pH by the AWRI.

The QTM conundrum

Humankind’s obsession with speed is also evident in the QTM movement. QTM stands for Quick to Market and typically refers to young red wines reaching the market, with its countless shelves, as soon as possible. Colloidally speaking, older reds tend to be more stable, but time is not a luxury one has when it comes to QTM wines. To speed this whole stability business up, the savvy winemaker needs to address its moving parts sharply. Enzyme additions as well as fining actions can already start at the juice stage, or even during AF, and will not only improve aspects such as early colour stability, but also make downstream actions, such as filtration, less frustrating. The addition of products post-AF to speed up and even simulate ageing (to a degree) has also become an affordable and practical reality.

Where colour and cold stability in QTM red wines were previously sometimes a bit of a brain teaser, nowadays combination products exist that can address both colour and cold stability simultaneously, and all of this very close to bottling!

Don’t believe it’s possible? Contact your Laffort technical human and we’ll show you how possible and easy it is to keep things stable.

Cheers!