Influence of the Wheat Flour Ozonation Process on Its Microbial Status and the Sensory and Mechanical Properties of Bakery Products

This study investigated the effect of ozonation of wheat flour (30 ppm O₃ for 30 min) on the microbiological status of flour, as well as the profile of volatile compounds, the mechanical properties, and the sensory characteristics of the resulting bakery products. Ozonation significantly reduced the microbial load of the flour, decreasing aerobic bacteria from 1.4 × 10⁵ to 1.7 × 10⁴ CFU·g⁻¹ and yeasts and moulds from 2.8 × 10³ to 1.3 × 10² CFU·g⁻¹, while lactic acid bacteria populations remained unchanged. HS-SPME-GC-MS analysis revealed that the ozonated flour contained six volatile compounds (compared to three in the control), predominantly nonanal (80.62%), an aldehyde formed via the ozonolysis of unsaturated fatty acids. Although these ozone-induced aldehydes were also detected in the final bakery products, their peak areas decreased substantially (to ≤3.3% of the flour values), suggesting thermal desorption during baking. Texture profile analysis demonstrated that products baked from ozonated flour exhibited increased hardness (Cycle 1: 68.06 N vs. 53.42 N; Cycle 2: 59.41 N vs. 47.52 N) and chewiness (427.95 mJ vs. 404.70 mJ) compared to controls. This textural degradation is likely due to ozone-induced modifications in enzyme activity (proteolytic, amylolytic, and lipolytic) and gluten protein cross-linking via disulphide bond formation. Furthermore, sensory evaluation using a five-point scale showed lower acceptability for the ozonated products (3.04 vs. 3.74), with panellists noting inferior taste, aroma, crumb colour, and flexibility. In conclusion, while ozonation effectively reduces the microbiological load of wheat flour, the applied high-dose treatment (30 ppm, 30 min) negatively impacts the sensory and textural quality of the bakery products, indicating that milder processing parameters are necessary to balance safety and quality.