Vinegar tasting beer. It's happened to 99% of all home brewers, you open a bottle of your newly brewed beer (after waiting for it to develop in the bottle) and you get whacked in the tongue with a horrible taste. Vile vinegar!\n\n\n\nSo, why does your home-brewed beer taste like vinegar? \n\n\n\nThe culprit is a bacteria known as acetobacter or Acetic Acid Bacteria. If developed in the brewing process it will lead to the production of organic acids and a vinegary taste. This is sometimes desired in the production of sour beers such as Lambic.\n\n\n\nHow does a beer develop a vinegar taste?\n\n\n\n\n\n\n\nThe acetobacter needs oxygen to do what it does best, produce acetic acid (that vinegar taste in your mouth right now). The most likely period of the brewing process when you could be exposed to acetobacter is during a transfer. Either when transferring your beer into your fermentor or, if still not fully fermented, when bottling or casking your wort. Limiting the exposure of your brew to the air in these stages is very important. However, you can't work in a completely air-free environment, so just try your best.\n\n\n\nAcetobacter not only needs oxygen, it also needs food. The ethanol in your beer, unfortunately, is just what it likes. So, this bacteria effectively transforms the alcohol you were hoping for in the beer into unwanted vinegar (acetic acid). If you were to leave the bacteria to it, after several months you'd have a batch of pretty much pure vinegar on your hands.\n\n\n\nNevertheless, simply exposing your beer brew to the air won't introduce acetobacter into the mix. Often poor sanitization of your equipment can be the cause of a vinegar tasting beer. Clean is the name of the game when it comes to home brewing. Always use something such as Star San or iodophor for best results (Amazon links).\n\n\n\nIf you have a secondary yeast introduced into your wort from a previous batch this can have disastrous results, including that vinegar taste. Also, this bacteria can get in from contamination from compromised equipment. Anything that comes into contact with your wort is a possible carrier of some undesired bacteria.\n\n\n\nCleaning your equipment thoroughly before and after use is essential. Also, consider your own interaction with the brew. Wearing latex gloves and scrubbing your surfaces isn't necessarily a step too far. Not everyone will want to take such an extreme step, and that's absolutely fine.\n\n\n\nMake sure that, if using them, your bottle caps and bottle capper are as clean as you can get them as it's impossible to rack and bottle your beer in a total air vacuum, therefore acetobacter could still be introduced at this late stage.\n\n\n\nAlso, consider the environment you are working in. Fruit flies are, for example, a notorious carrier of acetobacter. If you have fruit that is on the turn either eat it or throw it out way before you start a new homebrew. If you see these little pests in your brewing area, consider postponing your next batch and be prepared to lose your current beer baby.\n\n\n\n\n\n\n\nCan you fix the beer and remove the vinegar taste?\n\n\n\nIf you are already into the bottling process or are cracking open that first beer of the batch, it's probably too late to reverse a vinegar taste in your brew. It may be best to resign yourself to the fact that this beer is going down the plug hole.\n\n\n\nHowever, don't forget that that very same bacteria is used in the production of certain sour tasting beers such as lambics and German Gose beers. If you catch the problem fairly quickly after bottling your beer there is still an opportunity to get an unexpected sour beer out of it. This really depends on the recipe of the beer you have and will have to be discussed in another article.\n\n\n\nGenerally, though, this is beyond the skill of a new brewer and may not be to everyone personal taste.\n\n\n\nThe real issue here is that even if you could identify the bacteria from the appearance of your wort during the brewing process, it probably won't help you. Because acetobacter feeds on the ethanol content of your beer its presence effectively ruins your batch. Cut your loses and learn from the mistake. Keep everything clean and minimize the exposure of your home-brew to oxygen next time.\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n Plan your next Beer Creation?