Abstract
Bioactive peptides (BPs) are representing biologically active compounds primarily composed of short amino acid sequences. They hold considerable scientific importance due to their remarkable functional characteristics, which encompass, among others, antihypertensive, and antioxidant properties. These peptides have garnered significant attention within the scientific community owing to their potential in addressing various chronic conditions, and have carved out a valuable role in the industrial sector, providing numerous technological advantages such as the enhancement of food's nutritional and functional profile and the development of nutraceuticals. Amid the growing preference for plant-based foods, pulses, including red lentils, emerged as alternative sources of protein and BPs. In this comprehensive study, the impact of fermentation on red lentil protein isolate (RLPI) was investigated using various lactic acid bacteria and yeast strains. Notably, strong proteolytic activity was exhibited by Hanseniaspora uvarum SY1 and Fructilactobacillus sanfranciscensis E10, leading to the highest antiradical, antihypertensive, and antifungal activities, as identified in low molecular weight water-soluble extracts (LMW-WSE). Fermentation produced 12 peptides previously undetected in raw RLPI, including 36 sequences matching known BPs. The highest amounts of BPs were generated by SY1, particularly those with antioxidant and antihypertensive activities, tested in vitro, unveiling novel BPs in the fermented matrices. In addition, 44 potential BPs were associated with antifungal activity. Lentils, renowned for their high protein content, gained further significance as a staple food source in the context of increasing interest in alternative protein sources. Fermentation proved to be a sustainable and natural method for enhancing the nutritional properties of lentil proteins and promoting the production of BPs. A nutritional characterization of red lentil protein isolates (RLPIs) revealed that fermentation positively impacted amino acid (AA) concentration, in vitro protein digestibility (IVPD), and protein digestibility corrected amino acid score (PDCAAS). Fermentation not only increased AAs in RLPI but also boosted IVPD and PDCAAS through the reduction of antinutritional factors (ANFs). Subsequent testing in an in vitro simulator of the gastrointestinal tract showed that fermented (FRLPI) and raw unfermented RLPI (RRLPI) stimulated the production of short-chain fatty acids (SCFAs), with both FRLPI and RRLPI yielding similar results and a sustained effect post-intake interruption. The examination of low molecular weight (LMW) peptides further revealed the generation of 11 BPs composed of 4, 5, and 7 AAs in both FRLPI and RRLPI treatments. In another study, the untapped potential of apple flowers (AF) as a source of bioactive compounds was harnessed through microbial fermentation. Fructobacillus fructosus PL22 and Wickerhamomyces anomalus GY1 strains were employed, leading to significant improvements in the bioactive composition of AF. These strains induced substantial changes in the phenolic profile, released compounds known for their antioxidant and antifungal activities, and enhanced the production of antioxidative and antifungal amino acids and diverse LMW-peptides, enriching the bioactive potential of AF. The exploration of Asiago Protected Designation of Origin (PDO) cheese from different dairies and batches highlighted the impact of starter cultures on its chemical, microbiological, and BP profiles. The differences in microbial composition and the evolution of BPs were found to be distinguishable between dairies and batches. Furthermore, variations in BP intensities during ripening were closely related to proteolysis and exhibited antioxidant and ACE-inhibitory activities. The analysis emphasized the role of autochthonous strains in different dairy regions, reaffirming the significance of regional specificity within PDO production areas. Microbial fermentation of food waste to produce biopeptides poses challenges, primarily due to the diverse proteolytic abilities of microorganisms and substrate variability. To address these challenges, the novel bioinformatics tool FEEDS (Food wastE biopEptiDe claSsifier) was introduced, capable of predicting biopeptide families based on protease profiles and substrate composition. The tool's effectiveness was validated across 1000 microbial genomes, demonstrating its ability to categorize peptides reliably and guide biopeptide production through microbial fermentation. Finally, this study focused on recycling whey milk by-products in fruit smoothies through starter-assisted fermentation, aiming to deliver sustainable and nutritious food formulations. Five selected lactic acid bacteria strains optimized the production of smoothies, leading to distinct profiles of sugars, organic acids, ascorbic acid, phenolic compounds, and anthocyanins, notably enhancing protein digestibility and antioxidant capacity. These findings underscored the potential of microbial fermentation in developing sustainable and healthy food products, utilizing food waste, and enhancing nutritional value.