How to make stronger beer

PhD student Garry Smith is set to be the toast of student unions across the land, with research into brewing yeast that could produce stronger beer, writes Olga Wojtas.

Mr Smith, of the University of Abertay Dundee's division of molecular and life sciences, has been taking forward research by his supervisor, Graeme Walker, into boosting the physiology and nutrition of yeast used in modern brewing.

When malted barley is mixed with warm water, enzymes are released, converting starch into sugars, which the yeast then converts into alcohol.

"Brewers want to get as much use out of yeasts as possible. They reuse them a number of times, and as they get reused, they tend to get a bit sluggish," said Mr Smith, who has just presented his findings to the Institute of Brewing.

"My research has potential benefits for the brewing and fermentation industries, making yeasts more efficient alcohol-producing cell 'factories'."

Mr Smith has been adding extra magnesium to the yeasts, which he has found not only improves fermentation, but may also protect against the physical and chemical stresses the yeasts suffer before and during the fermentation process.

"This is quite a basic and simple technique, which we're hoping will make the yeasts more robust. It's not GM technology, but addresses aspects of yeast nutrition and physiology," he said.

The research has found the improved fermentation increases alcohol levels by a few per cent, which Mr Smith says would translate to a significant increase in yield for big companies.

"When friends and family hear what I'm doing, their eyes light up, and they ask whether they can come along and do some sampling," he said.

But student celebrations may be unwarranted, Mr Smith warns. "Stronger beer is not necessarily passed on to the customer. Usually modern brewing practices use quite a high sugar concentration, higher than the final beer product, so they dilute it down a wee bit."