LEUVEN, BELGIUM – Belgium famously produces hundreds of different beers, but that is nothing compared to the varieties of yeast used to make them -- around 30,000 are kept on ice at just one laboratory by scientists seeking the perfect ingredient for the perfect brew. A team from the University of Leuven and life sciences research institute VIB are examining and cross-breeding yeast strains, adding modern genetics to a search for brewing perfection that dates back centuries. "We're … using robots to cross different yeast like farmers have been doing with cattle and livestock for centuries," said genetics professor Kevin Verstrepen. "We're now doing the same with yeast on a massive scale, making millions of new strains or variants of yeast and testing which are the better ones." By analyzing the chemical and genetic basis of a beer's flavour and aroma, the scientists say they are breeding yeast strains that promote the best characteristics for a good beer.