Flour of banana (Musa AAA) peel as a source of antioxidant phenolic compounds

•Banana peel flour (BPF) is a profitable source of bioactive compounds.•BPF accounts for important amounts of highly polymerized prodelphinidins.•Complete series of 3-rutinoside of six flanovol aglycones occurs in BPF.•BPF also contains other flavonols, B-type procyanidins and flavanol monomers.•BPF shows very high antioxidant activity (FRAP, ABTS and ORAC).

Banana peel is an underused by-product that can be processed to obtain flour that is more easily stored for further uses. The extracts of banana peel flour exhibited a high total phenolic content (around 29 mg/g, as GAE) due to the occurrence of important amounts of flavonoid phenolics: highly polymerized prodelphinidins (around 3952 mg/kg), followed by decreasing lower contents of flavonol glycosides (mainly 3-rutinosides and predominantly quercetin-based structures, accounting for around 129 mg/kg), B-type procyanidin dimers and monomeric flavan-3-ols (jointly around 126 mg/kg). The high total phenolic content of extracts of banana peel flour is likely responsible for the very high antioxidant activity (μM/g, as Trolox equivalents) measured by three different methods: FRAP, around 14 μM/g; ABTS, around 242 μM/g; and ORAC, around 436 μM/g. All these results suggest the interest in going in depth of the good use of banana peel as a profitable source of bioactive phenolic compounds.