The airlock or or bubbler is one of the more important contraptions that a winemaker has in the cellar. This simple little device comes in several different styles with the most popular being the twin bubble and the cup in cup design. Both are very effective at allowing gasses out of the wine and creating an air tight seal (though I prefer the twin bubble for reasons I'll explain in a later post). Traditionally these airlocks are simply filled with water but this method creates a friendly environment for bacteria and spoilage organisms.
But how does the bacteria get in there?
The wine season in the northern hemisphere peaks in September and October, which also happens to be the peak fruit fly season. Fruit flies LOVE wine cellars, or anywhere near an actively fermenting wine. It is not uncommon to find a fruit fly or two in your airlocks, which is a little unsettling when you have paid so much for your grapes. Fruit flies are notorious for carrying spoilage organisms such as acetobacter, which is the catalyst for acetaldehyde, vinegar and the worst of all... ethyl acetate and it's signature nail polish remover smell. Needless to say, these are not things that you want in your wine. Proper use of sulfites in the wine can hedge against microbial problems but keeping an anti microbial environment in your airlock can help keep the bacteria from entering after it enters the carboy.
NOTE: Acetobacter and other spoilage organisms are often present on the grapes before even crushing but a pre-fermentation sulfite dose of up to 50ppm can help to reduce their grasp on the wine. Wine yeast (Saccharomyces cerevisiae) is extremely competitive during an active fermentation and often wipes out or reduces the populations of any other bad yeasts or wild bacteria. It is before and after the active fermentation that the wine becomes extremely vulnerable to acetobacter, brettanomyces, lactobacillus, and other problematic bacteria and yeasts. Now back on topic!
So, what should I put in my airlocks to help prevent this?
I like to use a strong ethanol such as grain alcohol (everclear), or 151 proof rum. Other, more budget friendly options include a Starsan solution or a strongly acidic solution (pH <2) . The main thing here is to make sure that whatever is in your airlock is wine friendly and antimicrobial. Though it is possible that some of the stronger solutions could weaken the plastic of your airlock, I have not found it to be a problem. Creating a harsh environment for microbes in your airlock is just one of the many tips and tricks that will help you to make better wine! Please use the subscribe button above to get email notifications when new tips and tricks become available.
If you have any comments, please share in the provided comments box below! I am always open to feedback, good or bad.
For more information about home winemaking, subscribe to my Youtube channel.
The Home Winemaking Channel