How the invention of the pH scale changed beer forever

When the scale to measure the pH level of beer was invented by a chemist in the Carlsberg research laboratory, it was shared with brewers around the world. As the Great British Beer Festival kicks off, Mick O’Hare tells the story

Beer wasn’t always so consistant. Even the same producer’s brews could be wildly different in quality (Getty/iStock)

Do you remember any chemistry from your schooldays? Dipping litmus paper into a liquid to see whether it was acid or alkali? If it was an acid the paper turned red, which meant its pH measurement was low, but if it was an alkali it turned blue, meaning its pH was high. Or was it the other way around? And what was pH? What do you mean you can’t remember... or you don’t care, even if you can?

OK, let’s make this a little bit more interesting. The Great British Beer Festival returns to London Olympia this week. Like so many events during these last two years, it has been a victim of Covid. But now the nation’s celebration of our favourite drink is back and delicious beers from porter to IPA, from amber ale to stout, will be downed by enthusiastic aficionados. But those beers might not be so delicious were it not for that pH scale.

Without knowing its pH, your beer could taste decidedly off. Which is what happened frequently before the turn of the 20th century, until a clever chap at the Carlsberg research labratory in Copenhagen invented a scale to measure it. And he invented it solely to make beer taste better. Paying attention now? And it wasn’t all that emerged from Carlsberg as we’ll see.