Browsing by Author "Navarro, Andrea"

Mold spoilage is the main cause of bread spoilage. The fungal species that mostly contaminate bakery products belong to the genera Penicillium, Eurotium, Aspergillus, Monilia, Endocymes, Cladosporium, Fusarium, Neurospora and Rhizopus. The aims of the experimental work were: (1) to screen LAB strains previously isolated from bakery and sourdough environment for their antifungal properties and to be used as starters for sourdough with antifungal activity, and (2) to evaluate sourdough effects on the shelf life of white wheat bread, without affecting the textural properties. Three methods were used to determine the antifungal activity of the isolates. First, the mechanism of fungal inhibition was investigated by an agar diffusion assay with P. paneum and P. albocoremium as indicators. The inhibitory activity toward bakery-related fungi was tested with the radial growth rate of fungi measured after seven days with six indicator molds. The isolates L. pentosus/plantarum J42 and L. mesenteroides I21 were tested in the baking trials, which were conducted in the pilot plant. Physicochemical analysis and microbiological observation were performed on bread slices and loaves produced with 30% sourdough, packed and stored in polyethylene plastic bags under natural conditions at a room temperature of ~ 24 ºC in the pilot plant. The water-soluble extracts from L. pentosus/plantarum, L. mesenteroides, P. pentosaceus and W. confusa had the highest inhibition activity. L. plantarum, W. confusa, L. pseudomesenteroides/mesenteroides and L. mindensis/crustorum had low activity toward the indicator molds. Minor inhibitory effect was observed toward P. albocoremium. Overall, the highest antifungal activity toward the indicator molds was shown by L. mesenteroides I21 strain. The pH values of the water-soluble extract and the sourdough did not seem to influence the fungistatic effect observed of the selected strains toward the molds. Addition of sourdough caused no changes in the physical properties of bread. Sourdough breads had less mycelial coverage relative to the control bread. In the conditions of this study, sourdough addition was beneficial to decrease mold contamination in bread.