Manufacturing the ultimate green banana flour: Impact of drying and extrusion on phenolic profile and starch bioaccessibility

Abstract Use of banana flours as functional ingredients is growing due to their nutritional benefits derived from phenolics and dietary fiber. However, the effect oven-drying, freeze-drying and extrusion on the phenolic compounds or starch digestibility is not understood. In this work, phenolic acids (gallic acid, caffeic acid), flavan-3-ols (epicatechin, catechin) and flavonols (quercetin-3-O-glucoside and myricetin) were quantified in banana flour processed by different methods. Epicatechin, the most abundant phenolic in all flours (up to 1.93 mg/100 g), was significantly reduced during thermal processing (oven-drying and extrusion). Meanwhile, phenolic acids and flavonols were found to be more thermally stable. Thus, oven-drying and extrusion generally improved the extractability of phenolic acids and flavonols. Freeze-drying resulted in native flours with significantly higher insoluble dietary fiber (up to 43.3 %), although the digestible starch fraction was digested more rapidly than the oven-dried counterpart.