Wine Flaw - Excessive Volatile Acidity

Ugh! My 2021 vintage has high volatile acidity (VA). It smells of pressed sugarcane juice and nail varnish. While I have made wine with high VA in the past, they were all within the threshold to be bottled and enjoyed. But the prospect for this vintage is dim. Hopefully, the addition of sulfites (sometimes referred to as SO2) will salvage some of it. 

Wait? Is sulfite the good guy now? What about VA? Let’s delve a little into the wine science. 

Nail varnish by Laura Chouette on Unsplash

What is VA?

VA is the measure of the volatile or gaseous acids in wine. The gaseous state of the acids is also the reason why VA can often be detected by smell. The aroma compounds that contribute to high VA in wine are primarily acetic acid (commonly known as vinegar) and secondarily ethyl acetate (associated with the smell of nail varnish). Oftentimes, the presence of VA is noticeable by the smell of nail varnish rather than that of vinegar. 

A certain amount of VA is acceptable and sometimes desirable to add to the character of a wine. Some sweet wines, such as Amarone della Valpolicella and Sauternes, and even dry ones, like Barolo, often accumulate a high level of VA. If you see the descriptor “lifted” in tasting notes or wine reviews, that’s what it means. However, when the level of VA results in an overpowering and off-putting aroma, it becomes unpleasant and can result in wine spoilage.

Acetic acid by CA Creative on Unsplash

VA is created by the activities of acetobacter. Acetobacter is a genus of acetic acid bacteria. It is widespread in nature and is responsible for creating vinegar, intentionally or otherwise. In winemaking, acetobacter can be found in bruised grapes, annoying fruit flies, winemaking equipment or anywhere in the cellar. Good sanitation practices, such as constant wiping down and cleaning with Star San, an acid-based sanitizer, is effective in limiting the presence of acetobacter.

SO2 versus VA

The reality is that it is nearly impossible to keep acetobacter out of the wine. The next layer of defense is to make the wine less conducive for bacterial activity. Acetobacter are aerobic organisms, which means they require oxygen to create havoc in the wine. Sulfite, an antioxidant, is often used to inhibit the microbial activity and growth. Yes, the much maligned sulfites are needed if you don’t want your wine to turn into vinegar.

Side note - How do natural wineries even make wine without adding sulfites? Maybe that is why natural wines often taste “interesting” and unpredictable!

Barrel tasting by Mauro Lima on Unsplash

Thankfully, modern science has crafted a formula to calculate the amount of sulfites needed for wine protection based on a number of parameters - such as pH and alcohol content. This hobby winemaker is just keeping up with it. 

Geek alert - As a rule of thumb, I have always targeted 50 ppm of FSO2 (parts per million of free sulfur dioxide) in the absence of a lab test. When sulfites are added to the wine, some will bind to the chemicals in the wine and some will dissipate. FSO2 refers to the remaining sulfur dioxide that is “free” or available to protect the wine. 

FSO2 need by pH level (Credits: enobytes.com)

As a hobby winemaker, I don’t perform multiple tests on my wine, unlike a commercial winery that would test throughout fermentation and aging. Instead, I tend to do a single broad spectrum test closer to bottling. Well, that did not work very well when the final test results indicated that the wine was not stable nor stabilizing.

My wine pH was >4.0, a first for me. Based on the chart above, I would have needed more than twice the regular SO2 dose to protect the wine. Even though I was dosing to achieve 50ppm FSO2, the test results showed that my FSO2 level was only at 4ppm. No wonder my wine is suffering from high VA. Recovery from high VA this late in the game is incredibly challenging. So lessons learned!

My Verdict: Rules of thumb are great until they don’t work. Learning from my own mistakes, albeit painful, sticks better. The good thing about winemaking is that if one vintage fails, you get to do it all over again the next year. You bet I’m going to do things differently, like doing focused tests on the wine and paying more attention to pH. I plan to kick VA in the butt for this next vintage. Wish me luck!

Sulfites Problems and The Magic Wand

Recently I had a few problems with sulfites in my wine. It is not what you think. In fact, it is probably the opposite of what you think. I forgot to add sulfites to my wine. I'll get into that in a minute. But first let's talk about more commonly known problems with sulfites - real and perceived.

Real Problem

Sulfites are naturally occurring compounds found in wine and other food sources such as peanuts, eggs, and tea. Because sulfites are also antioxidants, they are often added as preservatives to slow down browning or discoloration of food. 

In the 1970s as salad bars gained popularity in the United States, there was a dramatic uptick in the use of sulfites to keep the fruits and vegetables "fresh." With that came a rise in the cases of severe sulfite reactions. Sulfite sensitivity manifests in asthmatic symptoms such as wheezing and in rare cases anaphylactic reactions. Some people develop hives, swelling, or stomach pain. 

In 1986, the Food and Drug Administration (FDA) banned the use of sulfites in salad bars as a response to the increase in cases of sulfite allergy and sensitivity. It is estimated that about 1% of the population is sensitive to sulfites, and those with asthma are more susceptible.

Perceived Problem

Contrary to popular belief, headache is not a typical reaction to sulfites. But because many people suffer headaches from wine consumption, sulfites have become the easy target. In reality, wine-induced headaches are more likely due to dehydration from alcohol consumption or from the histamines and other compounds in wine. 

Wine wands

That said, the market wastes no time in capitalizing on the perceived problem of sulfites by offering a multitude of solutions, from sulfite-free wines to sulfite-removing wands, filters, and drops. While these may be effective in removing sulfites, one wonders if they eliminate wine-induced headaches or hangover since there is no scientific evidence that sulfites are the cause. There is however no accounting for the placebo effect.

Too Little Sulfites

The addition of sulfites during winemaking is necessary for the production of high-quality wine. Winemakers often pitch potassium metabisulfites into the wine post-fermentation to protect it from spoilage. When sulfites come into contact with the water in the wine, sulfur dioxide (SO2) is released. A portion of the SO2 will immediately bind with certain chemicals in the wine while the remainder will be in a free state (FSO2) to take on harmful microorganisms and to slow down premature aging of the wine.

Wine by Vladimir Fedotov on Unsplash

My first problem for my 2020 vintage is that I forgot my post-fermentation sulfites. While the science behind how much and when to add sulfites is complex and entails conducting multiple tests, a good rule of thumb for hobby winemakers is to pitch a certain amount every month to ensure adequate protection of the wine. And I did none of that this past vintage.

It was not till I ran a pre-bottling panel on my wine four months after fermentation that I found out that there were only 2 parts per million (ppm) of FSO2 in my wine. That is winemaker's talk for virtually zero protection for my wine from spoilage. 

Using the pandemic analogy, it is like going to a store without the protection of a mask or vaccination and hoping not to catch COVID. Thankfully, the wine was still tasting fine.

Too Much Sulfites

In my moment of panic, I googled the first website that gave me the target FSO2 level based on my wine pH. I did a quick calculation and pitched the sulfites as quickly as I could. Then I found a couple more websites that suggested target FSO2 levels that were significantly lower than the first website. One of the later websites had a target FSO2 level that was half of what I had pitched.

Great! Now a giant sulfite-removing magic wand doesn't sound so bad.

The truth is that it is hard to determine the right level of FSO2. Each wine's chemical makeup presents numerous variables that may bind with the sulfites, making it hard to determine how much FSO2 is left without running yet another test. Too much sulfites will inhibit the wine's ability to develop in complexity and give the wine a chemically metallic taste. Too little sulfites will increase the chance of spoilage. The winemaker treads lightly between the two.

Using the pandemic analogy again, it is like wearing five masks to the store which may protect you from COVID, but you may not be able to breathe.

Wine racking

Since I don't have a giant magic sulfite-removing wand, I decided my best recourse is to rack the wine despite mixed reviews with this approach. Put simply, wine racking is siphoning wine from one vessel to another, a process that introduces oxygen that will hopefully bind with excess sulfites. 

My Verdict: This is my fifth vintage. With every vintage, you learn something new that will help you improve your winemaking skills for the next vintage. There is no magic wand in that. I will let you know in 6 to 12 months how the vintage tastes.