Impact of Co-Delivery of EGCG and Tuna Oil within a Broccoli Matrix on Human Gut Microbiota, Phenolic Metabolites and Short Chain Fatty Acids In Vitro

(-)-Epigallocatechin gallate (EGCG) and tuna oil (TO) are beneficial bioactive compounds. EGCG, TO or a combination of, delivered by broccoli by-products (BBP), were added to an in vitro anaerobic fermentation system containing human fecal inocula to examine their ability to generate short-chain fatty acids (SCFA), metabolize EGCG and change the gut microbiota population (assessed by 16 S gene sequencing). Following 24 h fermentation, EGCG was hydrolyzed to (-)-epigallocatechin and gallic acid. EGCG significantly inhibited the production of SCFA (p < 0.05). Total SCFA in facal slurries with BBP or TO-BBP (48–49 µmol/mL) were significantly higher (p < 0.05) than the negative control with cellulose (21 µmol/mL). EGCG-BBP and TO-EGCG-BBP treatment increased the relative abundance of Gluconacetobacter, Klebsiella and Trabulsiella. BBP and TO-BBP showed the greatest potential for improving gut health with the growth promotion of high butyrate producers, including Collinsella aerofaciens, Bacillus coagulans and Lactobacillus reuteri.