Faculty of Bioscience Engineering, Department of Food Technology, Safety and Health, Ghent, Belgium
Awareness for clean label food products is rapidly increasing among consumers and has necessitated research to develop natural preservation strategies. Microbiological spoilage of bread is primarily an issue for products intended to be stored at room temperature for a longer period than the time needed to be rejected because of staling, e.g. packaged sliced toast bread and par-baked (PB) breads packed under modified atmosphere (MA). In this study, the potential of natural preservation strategies, including production/baking conditions, essential oils, sourdough and packaging has been investigated. The antimicrobial efficacy of antifungal compounds was assessed through in-vitro studies and growth/no-growth modelling. Visual shelf-life and microbiological tests were performed on bread to validate these results. Microbiological analysis showed that sourdough (SD) had the best preservation potential, followed by MA-packaging. Moreover, the production of composite bread proved to be even more promising. The shelf-life of PB bread was increased with ? 60 g SD/100g crust dough for air-packaed and ? 20g SD for MA-packed breads. Use of 60g SD/100g crust dough was sufficient to achieve the same level of preservation with or without MAP. Despite the pH-lowering effect of sourdough, the antifungal effect was not directly pH-related. Therefore, the in-vitro effect of natural organic acids, which are formed in sourdough, was assessed and validated in bread to determine to what extent organic acids are responsible for the shelf-life increase. This study showed that by adjusting the par-baking conditions, bread composition and packaging the shelf-life of par-baked bread can be extended in a natural way.