OnTap Magazine

BEERGINNER’S GUIDE DIRTY CLEAN DANIE ODENDAAL I nervously walk into the pub and I think “please, please let this be good”. I sit down and scan the tables as well as the bar counter. I am looking for any untoward evidence. e barman, fully masked, is starting to pour a beer. It pours in slow motion, tumbling and swirling into the glass. As he is pouring, carbon dioxide bubbles appear and make a break for freedom resulting in the formation of a luscious foamy head. I look for the signs. Will it be ok? “What am I worrying about?” you ask. Is this about a potential COVID risk? Am I being too pedantic? Is my thirst clouding my judgement? No. It might seem odd but this high-level angst that comes with ordering a beer is about one simple thing – whether that beer will be served in a clean glass. ere is nothing as heavenly as a beautiful beer presented in the most pristine glassware. My mouth waters at the very thought. But just as a perfectly washed and rinsed glass can make a drinker’s day, so can a dirty one ruin the sipping experience. Not all beer glasses are equal. You might not realise it, but your beer can instantly tell you whether the publican has taken the e ort to ensure that your glass is perfectly clean. We are not talking about obvious visual dirt but what you cannot see until the beer is poured. Two main aspects inherent in beer work as a litmus test for judging whether your glass is “beer clean”. ey can reveal the way the glass was treated before the nectar of the gods was poured into it. CARBONATION Most beers are super saturated with CO 2 at atmospheric pressure in your glass. is gas is looking for any opportunity to escape from the liquid. A clean class is smooth and does not allow bubbles to adhere to the sides. A dirty glass creates nucleation points for CO 2 to form a point to escape from. Be aware many beer glasses have etching on the bottom to allow for CO 2 nucleation and constant beading. is makes the beer appear lively and helps build the beer foam layer. But all those bubbles stuck to the side of your glass are a sure sign that no beer should ever have been poured into it. FOAM FORMATION AND STAYING POWER If a beer is carbonated on pouring, the components in the beer conspire to form beautiful foam and lacing on the inside of your glass. Beer foam is made up of protein, iso alpha acids, metal cations and other components. If the glass isn’t perfectly clean it will destabilise the foam bubble, quickly destroying the dense foam head. e foam bubble coalescence is accelerated, resulting in bubbles merging and forming random sized bubbles as the u y white crown rapidly collapses. Instant foam-killers are residual fats, perhaps from piling glasses into the dishwasher alongside grubby plates, and dishwashing soap that hasn’t been properly rinsed away. Yes, I hate it when a beer reveals to my eye a carelessly washed glass – and so should you. at beer is the product of a long supply chain of passionate people: the farmers, the maltsters, the brewers and the publican or restaurateur. For that beer to be let down at the nal moment by something as easily avoidable as a dirty glass is, put simply, a total tragedy. SEND IT BACK If you spot the tell- tale signs of unclean glassware, you’re well within your rights to send back your pint and request a fresh one. Carbonation bubbles stuck to the inside of the glass or a rapidly diminishing head are the main indicators. And it’s not just about aesthetics. Carbonation and foam both play a role in the aroma and flavour of your beer and a dirty glass can quickly ruin your enjoyment of that well-earned pint. 50 | Winter 2021 | ontapmag.co.za