Synergistic Action of Multiple Enzymes Resulting in Efficient Hydrolysis of Banana Bracts and Products with Improved Antioxidant Properties

This study investigated the effect of enzymatic hydrolysis of banana bracts from different varieties (Maçã, Nanica and Prata) using pectinase, protease and cellulase (singly or in combinations) on their antioxidant properties. The results showed that the antioxidant properties and total phenolic compounds (TPC) of extracts increased after the enzymatic treatment with a clear synergistic effect between the different enzymes. The ternary mixture of pectinase, protease and cellulase resulted in increases of 458% and 678% in TPC content for extracts obtained from Maçã and Nanica varieties and up to 65% in antioxidant properties of those produced from Prata variety compared to the non-hydrolyzed samples. In general, the extracts obtained from the Prata variety showed the highest levels of TPC, as well as antioxidant activity, as follows: 14.70 mg GAE g−1 for TPC, 82.57 µmol TE g−1 for ABTS, 22.26 µmol TE g−1 for DPPH and 47.09 µmol TE g−1 for FRAP. Phenolic compounds identified by HPLC in extracts included ρ-coumaric, ferulic, sinapic and vanillic acids and the flavonoid rutin. This study reported for the first time the enzymatic treatment applied to banana bracts as a promising method to release antioxidant compounds, offering a new opportunity to explore these residues as a source of molecules with high added value through an environmentally friendly and safe process.