Native fruits are gaining popularity in national and international markets, attributed to their unique flavors and health benefits due to high bioactive concentrations, especially phenolic compounds. The fermentation process of native fruits such as mangaba and bacaba have been highlighted, as they are rich in vitamins and minerals and contribute a considerable quantity of flavonoids, phenolic acids, and stilbenes. More interesting than just evaluating the content of phenolic compounds present in food matrices is determining bioaccessibility through in vitro digestion simulations, and it is important to know the fraction of the compounds that are biotransformed by these microorganisms to better understand the potential of these products as functional foods. This chapter details the methodology for extracting phenolic compounds from fermented native fruits and analyzing simulated gastrointestinal digestion to evaluate phenolic bioaccessibility.