Contribution of sourdough fermentation and yeast invertase to degradation of FODMAPs in sourdough bread and pasta

The reduction of fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAP) in grain-based food products is of interest for alleviating symptoms of irritable bowel syndrome (IBS) and non-celiac wheat sensitivity. This study investigated the contribution of sourdough fermentation to reduce starch digestibility and FODMAP levels in bread and pasta produced from the same durum wheat flour. The study employed a commercial sourdough starter culture composed of homofermentative and heterofermentative lactic acid bacteria but the quantification of acetic and lactic acids documented that homofermentative lactic acid bacteria were dominant in the sourdough fermentation. Sourdough fermentation did not reduce (P > 0.05) the concentration of fructo-oligosaccharides in the sourdough. Likewise, sourdough fermentation did not reduce (P > 0.05) the in vitro digestibility of starch in pasta or bread. The content of fructo-oligosaccharides remained unchanged (P > 0.05) at about 10 mg/g when sourdough was included in pasta making. In bread making, where baker’s yeast was included as leavening agent, the FODMAP content was reduced by more than 90%. In conclusion, yeast invertase activity together with a sufficient fermentation time suffice to reduce FODMAP levels in bread. Effective FODMAP reduction by sourdough fermentation requires the selection of fermentation microbes that hydrolyze FODMAPs. Fermentation processes and strain selection to reduce FODMAP levels in pasta production to provide options for individuals with IBS and non-celiac wheat sensitivity remain subject to future investigations.