Technological and microbiological characterization of an industrial soft-sliced bread enriched with chitosan and its prebiotic activity.

Several studies have described the effects of chitosan as an ingredient in bread, particularly from a technological and functional point of view. However, these studies mainly focus on breads produced at lab scale with a short shelf life, which may not reflect the changes occurring in industrial production. Our study investigated the potential of using chitosan at an industrial scale to produce soft white bread, evaluating its impact on the final product's shelf life and providing deeper insights into the practical possibilities and limitations of its scalability. In particular, the rheological properties of the dough and the overall qualitative characteristics of the breads were evaluated when chitosan was used at 0.75 and 1.5%. The use of chitosan in bread dough increased its viscoelasticity, firmness and extensibility, making the dough more elastic but harder to mold and process industrially (extension resistance: 41.70 for 1.5% chitosan vs 22.55 for the control). Chitosan breads exhibited higher pH, aw (1.5%: 0.955 vs control: 0.934), firmness and a larger pore size, with a lower cut height and a more pronounced colour due to increased Maillard reactions. Microbiologically, the chitosan breads were within acceptable limits (<4 and 3 log CFU/g for aerobic mesophilic bacteria and yeasts, respectively) but showed no effect on spoilage microbiota. However, the addition of chitosan increased the prebiotic activity of the bread, as assessed by its ability to promote the growth of selected probiotics in simulated intestinal fluid, which has the potential to positively impact consumers' gut health.