(BBC) - It’s a drink that’s been with us for millennia. But how has science shaped today’s pints? Chris Baraniuk discovers a world of secret yeasts, strange brews and ‘glass widgets’.

Venture through a dank railway tunnel, then turn on to a small industrial estate in south east London and you’ll find yourself at a fine example of a British brewery. But there are no rambling roses or tumble-down ancient buildings crying of English tradition here. The Kernel brewery is little more than five years old and the beer produced in this urban hideaway combines old traditions with new thinking – and a little experimentation.

“We rely on that process of hypothesis, experiment and result,” says brewer Toby Munn. “We can create our own little experiment and do all kinds of different things, which is fun.”

Munn shows off the fermentation tanks, where yeast gradually turns sugars into alcohol over several days, and a room full of barrels and large French “fouders”, which were previously used in wine-making.

There is also a lab, not much bigger than a walk-in wardrobe, but its size does no justice to its significance. A microscope takes pride of place, but nearby are other instruments for measuring the density of liquids and a curious looking contraption for acceleration of the fermentation process by the gentle heating of beer.

Making beer is sometimes seen as something of an art, but once you get to larger scales, science is vital. Whether you’re an up-and-coming outfit like Munn’s or a multinational brand like Guinness or Budweiser, the key to succeeding as a brewery is shrewd scientific analysis of your product and some clever chemistry.

Repeat trick

For starters, a lot of thought goes into making beer taste the same worldwide, especially among multi-national brands. The yeast, for example, must be consistent, says Chris Giles, owner of Surebrew, a firm which provides chemical analysis and yeast storing services for breweries. “You can freeze that culture down and preserve it as a snapshot of what they want. Then we supply back every three to six months so they can brew beer in the same style with the same flavour profile.”