However, finding strains that could outcompete the undesirables and produce high quality chocolate proved highly challenging. The investigators characterized more than 1,000 strains of Saccharomyces cerevisiae, mostly from the alcoholic beverage industry, but including some from cacao farms. Some of the best performers came from the latter, and others came from the beer, wine, bioethanol, and sake industries, said Verstrepen. A key to success was the ability to tolerate the high temperatures encountered during cocoa fermentation--45°-50° centigrade (107.6°-109.4° Fahrenheit).