Tailored organosolv banana peels lignins: Improved thermal, antioxidant and antimicrobial performances by controlling process parameters.

Abstract There is a growing environmental concern in the world for replacing the traditional petroleum-based products. The aim of this work was to evaluate the structure – property relationship of banana peel lignins (BPLs) as antioxidant and antimicrobial agents by controlling the parameters of organosolv process. The milled banana peel was hydrolyzed using an aqueous acetic acid solution (70, 80 and 90% v/v) and 2.0% v/v HCl at 110 °C for 1, 2 and 3 h. BPLs were characterized by FTIR, 1H NMR, 1H 13C HSQC, 31P NMR, GPC and TGA. The antioxidant capacity of BPLs was evaluated by DPPH, ABTS and H2O2 assays, comparing their performance with that of ascorbic and gallic acid. The antimicrobial activity of BPLs was evaluated against E. coli. The reaction time and acetic acid/water ratio had significant effects on the yield and purity of BPLs. The composition of organosolv solution also affected their total amount of hydroxyls (0.71–0.82 mmol g−1), Mw (2759–3954 g mol−1), Tonset (232–254 °C), antioxidant and antimicrobial activities. It can be concluded that the control of organosolv parameters can be a useful tool for tuning the structural features of lignins and to maximize their performance.