Evaluation of amla and tomato pomace for polyphenol bioaccessibility and prebiotic effects by <i>in vitro</i> digestion and fermentation

Purpose This paper aims to determine the impact of in vitro gastrointestinal digestion (IVD) on the bioaccessibility of phenolic compounds derived from tomato pomace flour (TPF) and amla pomace flour (APF), and to evaluate their potential health benefits as prebiotics on gut microbiota. Design/methodology/approach The nutritional and functional properties and the bioaccessibility of phenolic compounds obtained from APF and TPF were measured using IVD model and the potential prebiotic effects were assessed during in vitro fermentation. Findings APF and TPF contained significant amounts of total dietary fibre (55.83% and 48.29%, respectively) and protein (2.1% and 14.37%, respectively). After IVD, a considerable amount of polyphenols from APF and TPF were released. In the intestinal phase, APF and TPF showed significant ( p = 0.05) release of total phenolics (81% and 57%, respectively) and flavonoids (84% and 76%, respectively). Additionally, in comparison to the control samples, IVD increased antioxidant capacity. The proliferation of bacteria ( L. acidophilus ) and the production of short-chain fatty acids (SCFAs), including propionate and butyrate, were both increased during in vitro fermentation of APF and TPF. Both the flours showed a positive prebiotic activity with the value of &lt;1.50. Social implications The study supports sustainable agriculture and global pollution reduction. Incorporating these by-products into diets might increase the availability of inexpensive, nutritious food choices, improve digestive health and create economic possibilities for food producers and farmers. Originality/value The research provides novel information on the bioaccessibility of polyphenols and antioxidants during digestion, and the prebiotic potential APF, which have not been previously documented.