This is one that divides crowds. Brettanomyces is a type of yeast that can make its way into wine via the vineyard or winery, producing aromas of barnyard, horse or plasters. Interestingly it isn’t a fault in beer; in fact, it’s an important yeast used by brewers to make traditional styles of beer both here and in Belgium.

In small quantities, “brett” can add a layer of complexity to wine; in high quantities, however, it can be unpleasant. You’re more likely to find it in reds than whites (it’s also quite common in orange wine or skin-contact whites). Certain grapes’ natural flavour profile includes aromas that are similar to those produced by brett – particularly Syrah and Mourvèdre, which tend to have a leathery, savoury note. The level at which brett becomes a fault is subjective, and the wine won’t be harmful, no matter how bretty it is.

Next time, we’ll be looking at light strike. Follow our series on wine faults here.