A – Z of Flavour – Butyric
Butyric acid…A taproom classic for people to mention wanting to cause trouble, a word that instils fear and pain in the hearts of brewers and salespeople alike. Commonly described as ‘Baby Sick’, ‘Parmesan Cheese’, ‘Rancid’…not words that entice when used to describe the much anticipated first pint at the end of the day.
utyric acid is a short chain fatty acid formed in beer as result of contaminant bacteria during production, or in pack. The first instance Butyric can occur is during mashing and sweet wort separation. Issues occur when delays in the brew house allow mashing to go on too long, coupled with reduced temperatures. You can make sure you defend yourself with regular in-process sensory assessment alongside your in-process micro regime. Ensure the use of ‘taste gates’ (Go/No Go sign-off from trained tasters) before moving product around the brewery. If you have detected Butyric in-process immediately begin deep clean from the heat exchange onwards and validate cleaning with full micro.
It can also rear its ugly head in packaged product, again due to bacterial spoilage. Anaerobic bacteria such as Pectinatus and Megasphaera work their magic with lower ABV beers, and with very low DO in pack. Sadly, this is one of the few side effects of the super low DO levels we all strive for. It’s worth remembering that in pack Butyric acid may not be present in every can/bottle of the run. This may be the case if, for instance, the spoilage is coming from a single can head on the filler, or maybe some spray coming from the floor hitting only a few cans on the bottom of the stack. Personal anecdote incoming…I once had a run-in with Megasphaera that was showing in only 1 in around 40 cans within a 30 minute time window (don’t even ask how much time or how many cans I had to open to work this out), this could have led to hundreds of ‘baby vomit’ cans being out in trade, it goes without saying that this would be immensely damaging for brand equity. The experience taught me the value of keeping plenty of retention stock from various times throughout the run, undertaking regular sensory on fresh and aged product, and as ever…keeping your packaging line spotless.
The flavour threshold of butyric acid in beer is 3 mg / l, but it’s worth noting that this is reduced when coupled with Diacetyl. Diacetyl can be a common confusion for sensory tasters, as well as Ethyl Butyrate and Isovaleric, highlighting the importance of training tasters all 4 so people can identify differences and feedback correctly.
Butyric and beer are a terrible combo, nobody’s arguing that… but shall we try and give Butyric a glimmer of hope before we write it off completely? To do this though we need to move away from beer and consider that it can be present in some things we love, such as some chocolate.
In particular American-style chocolate such as the famous Hersheys, where Butyric acid provides a distinctive and delicious ‘tang’ that millions love so much. So maybe next time you are in a taproom, and want to break it to the brewer that there maybe be an issue with their can filler, could we talk ‘chocolate’ rather than ‘baby vomit’ to ease the pain a little?