Thirteen wheat (Triticum durum and Triticum aestivum) flour samples (Table 1) were collected from several bakeries throughout Sicily (southern Italy) from January to May 2012, immediately before the mature sourdough was refreshed. Samples were chosen for their typical characteristics and/or origin. Many of the flours are unique to local Sicilian milling, while others are also commercially available outside Sicily. Flour samples were transferred into sterile Stomacher bags and placed into a portable cooler. Once in the laboratory, all samples were refrigerated until analysed.