Sourdough starters in the Puratos Sourdough Library. While there, we visit the world's first and only Sourdough Library, learn how the microbes in sourdough improves the texture, flavor, and nutritional quality of bread, and eat our body weight in baked goods. Karl de Smedt, who also manages training and communications at Puratos, launched the Puratos Sourdough Library in 2013: it's the largest collection of of sourdough starter microbial diversity in the world.