Abstract
The use of olive pomace could represent an innovative and low-cost strategy to formulate healthier and value-added foods, and bakery products are good candidates for enrichment. In this work, we explored the prebiotic potential of bread enriched with Polyphenol Rich Fiber (PRF), a defatted olive pomace byproduct previously studied in the European Project H2020 EcoProlive. To this aim, after in vitro digestion, the PRF-enriched bread, its standard control, and fructo-oligosaccharides (FOS) underwent distal colonic fermentation using the in vitro colon model MICODE (multi-unit colon gut model). Sampling was done prior, over and after 24 h of fermentation, then metabolomic analysis by Solid Phase Micro Extraction Gas Chromatography Mass Spectrometry (SPME GCMS), 16S-rDNA genomic sequencing of colonic microbiota by MiSeq, and absolute quantification of main bacterial species by qPCR were performed. The results indicated that PRF-enriched bread generated positive effects on the host gut model: (i) surge in eubiosis; (ii) increased abundance of beneficial bacterial groups, such as Bifidobacteriaceae and Lactobacillales; (iii) production of certain bioactive metabolites, such as low organic fatty acids; (iv) reduction in detrimental compounds, such as skatole. Our study not only evidenced the prebiotic role of PRF-enriched bread, thereby paving the road for further use of olive by-products, but also highlighted the potential of the in vitro gut model MICODE in the critical evaluation of functionality of food prototypes as modulators of the gut microbiota.
Highlights
The exploitation of byproducts from industrial processing of natural feedstocks is a fundamental requisite for sustainability and to contrast pollution generated by synthetic the production of compounds
The Good’s rarity index was unchanged (p > 0.05), indicating the ability of MICODE to support the growth of rare and fastidious species, while the Observed Operational Taxonomic Units (OTUs) richness index scored more than 400 OTUs at the endpoints. (iv) The paradigm of prebiotics was confirmed; a massive probiotic and Short Chain Fatty Acids (SCFAs) increase and a minimal depletion of enteropathogens were recorded when FOS
To analyze the main changes in volatile microbial metabolites related to prebiotic potential, we considered the shift in loads from the baseline to the endpoint (24 h) of the fermentation of 13 selected VOCs with renowned bioactivity in humans (SCFAs, Medium-Chain Fatty Acids (MCFAs), Branched-Chain Fatty Acids (BCFAs), Indole and Skatole) as follows: (a) each single compound was normalized within its dataset, which included cases from different type of sample; (b) the baseline dataset (Table S2) was subtracted to the endpoint dataset; (c) post-hoc analysis was done to compare the sample productions of a single molecule (Tukey’s honestly significant differences (HSD), p < 0.05)
Summary
The exploitation of byproducts from industrial processing of natural feedstocks is a fundamental requisite for sustainability and to contrast pollution generated by synthetic the production of compounds. Considering the use of PRF as an innovative and low-cost strategy to formulate healthier and value-added foods, its impact on human colon microbiota and putatively prebiotic potential deserve attention. Prebiotics have essential features [3] expressed towards the amelioration of host health, such as the modulation of the microbiota-fostering beneficials while relenting pathogens, as well as the production of microbial compounds, which, in turn, are good for the host, such as principal SCFAs [4,5]. In vitro gut models are considered a proper solution because they can explain the impact of prebiotics on human gut microbiota, focusing on the shift in the core microbial groups and that of selected species and their metabolites, assaying diversity, richness, composition, and abundance in the community over time [11]. For the first time, we are presenting Multi-Unit In vitro Colon
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