Degradation of fibres from fruit by-products allows selective modulation of the gut bacteria in an in vitro model of the proximal colon

The potential prebiotic effect of fibres (alcohol insoluble solids fractions) from fruit by-products – orange bagasses and passion fruit peels – and their degradation by human gut microbiota was tested in an in vitro colon system. Standard medium and inulin were used as controls. Orange bagasses (A-OB1 and A-OB2) had similar chemical composition but differed regarding fermentation profile. A-OB2 resulted in a more diverse bacterial community than A-OB1 and produced more SCFA, with increased Ruminococcus and Lachnospira. Carbohydrate utilization was higher on A-OB2 probably due to higher ratio soluble to insoluble fibres. Isolated fibres from passion fruit peels presented similar chemical composition and fermentation profiling. Bacteroides and Ruminococcus were the main genera stimulated. Negligible lactate and succinate production represent slow fermentation, a protective feature against colon cancer. This study provided evidence that the tested fruit by-products have the potential to be used for selective modulation of the gut microbiota.