Abstract
Fermentation is a fundamental biotechnological process that enhances the nutritional quality, digestibility, and bioavailability of food components while many fermented food have the powder to modulate the gut microbiota promoting beneficial metabolic responses. This thesis investigates the impact of fermentation by lactic acid bacteria and yeasts on different food matrices—including, baked goods and plant-based protein isolates—focusing on their biochemical transformations, digestibility, and potential health benefits. By integrating advanced analytical techniques and in vitro digestion models, this work provides a comprehensive evaluation of how fermentation can influence nutrient availability, protein quality, and the evolution of gut ecosystem. The first study examines Pinsa Romana, a traditional Italian pizza variety, analyzing the effects of fermentation processes characterized by different parameters on its nutritional profile and digestibility. The results demonstrate that using a sourdough-based biga fermentation with prolonged fermentation times, leads to significant improvements in protein quality indexes, enhances amino acid bioavailability, and lowers the predicted glycemic index. Furthermore, simulated in vitro digestion reveals that this fermentation strategy modulates the release of bioactive peptides, suggesting potential metabolic advantages. The second study focuses on the development of novel sourdough breads fortified with plant-based ingredients, namely fermented apple by-products, avocado, and walnut. By screening microbial consortia of lactic acid bacteria (LAB) and yeasts, an optimal consortium of starters was selected to maximize, in the final sourdough breads, the production of free amino acids, improve protein digestibility, and lower the glycemic response. The results indicate that these fortified sourdough breads not only exhibit improved macronutrient digestibility and higher bioactive compound content (e.g., phenolics and unsaturated fatty acids) but also exert a prebiotic-like effect by promoting the production of short-chain fatty acids (SCFAs) and beneficial bacterial taxa through the Simulator of Human Intestinal Microbial Ecosystem (SHIME), a validated in vitro gut model. The third study shifts the focus toward plant-based protein alternatives, exploring the fermentation of red lentil protein isolates and their influence on gut microbial ecosystem. Fermentation with Hanseniaspora uvarum SY1 significantly improves protein digestibility, enhances the release of bioactive peptides, and increases the bioavailability of essential amino acids. Moreover, the SHIME in vitro gut model reveals that fermented lentil protein isolates promote the growth of beneficial bacteria genera such as Lactiplantibacillus and Furfurilactobacillus, known for their probiotic potential. The fermentation process also stimulates the production of butyrate, which is associated with gut barrier integrity and anti-inflammatory effects. Additionally, the release of low-molecular-weight peptides with antioxidant and ACE-inhibitory activities suggests potential cardiometabolic benefits, reinforcing the role of fermentation in developing functional plant-based protein ingredients. Overall, these studies highlight the critical role of fermentation in improving the digestibility and nutritional properties of diverse food matrices, while also positively influencing gut microbiota composition and metabolic responses. By bridging food science, biochemistry, and gut health research, these findings contribute to the development of next-generation functional foods with enhanced health benefits.