Development of sourdough fermentation protocols for an extended mold-free storage life of packaged pan bread

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Microbial spoilage of bread is caused by rope-forming bacilli, which invariably occur in wheat and rye flour as they are deposited in cereal grains as seed endophytes, and by mycelial fungi (molds), which contaminate bread after baking. The use of even low amounts of sourdough or sourdough-based bread improvers reliably inhibits spoilage by bacilli but the use of sourdough is typically insufficient to completely inhibit mold growth during a storage time of more than 3 weeks. Metabolites of lactobacilli with antifungal activity include acetic acid, propionic acid, long-chain hydroxy fatty acids, phenyllactic acid, and cyclic dipeptides. These antifungal metabolites are either not produced in concentrations that are sufficient to inhibit mold growth (long-chain hydroxy fatty acids, phenyllactic acids and cyclic dipeptides), or negatively impact bread quality when present in antifungal concentrations (acetic acid, propionic acid, cyclic dipeptides). Successful approaches to extend the mould-free storage life of bread therefore combined antifungal metabolites of lactobacilli, particularly acetic acid, with antifungal additives, e.g. sorbic or propionic acids, or ingredients with antifungal components, e.g. hop extracts, plant extracts rich in phenolic acids, or plant seed oil from which antifungal fatty acids can be released by lipolysis. This 3 year project project generally aims to develop a sourdough fermentation process that contributes to the mold free shelf life of bread, and to identify ingredients with antifungal activity that complement the antifungal activity of sourdough and achieves a mold-free storage life that matches industry standards.