Dietary fibre concentrates from avocado and mango by-products; antioxidant capacity and polyphenols evaluation by HPLC-IDA-EPI-MS

Phenolics bound to dietary fibres (DF-PCs) represent a valuable source of antioxidants that are often wasted. DF-PCs can be obtained as residues from conventional extraction processes of PCs derived from agro-industrial by-products. This study aimed to characterise DF-PCs generated after the PC extraction process from the avocado peel (AP), mango peel (MP) and husk mango seed (testa) (MT), with a focus on solid residue or concentrated fibre (APFT: avocado peel fibre; MPFT: mango peel fibre; MTFT: mango testa fibre). The by-products were evaluated under both non-defatted and defatted conditions before simulating the PC extraction process. PCs were quantified (TPC) and identified (HPLC-IDA-EPI-MS). Their antioxidant activity (AA) was determined (ABTS+, DPPH* and FRAP). Among the evaluated fibres, non-defatted AP and defatted MP and MT exhibited the highest TPC content (22.64 +/- 0.3, 37.31 +/- 1.78 and 6.07 +/- 0.08 mg GAE/g), respectively. Using the DPPH* assay, all fibre concentrates showed lower AA compared to the by-products. Using FRAP assay, defatting gave the largest activity for mango samples. HPLC-IDA-EPI-MS analysis of PC profiles resulted in the presence of 62 PC compounds in the fibre concentrates. These DF-PCs, with a significant content of PCs, may be relevant as functional ingredients for food production.