Microwave-enzyme-assisted extraction of pectin from feijoa (Acca sellowiana) fruit: Extraction optimization, physicochemical and functional properties

This study aimed to optimize the extraction of feijoa pulp pectin and discuss the impact of different extraction methods on the physicochemical and functional properties of pectin. Under the optimum conditions, the pectin yields of microwave-enzyme-assisted extraction (PMEAE, 13.31%) and enzyme-assisted extraction (PEAE, 9.26%) were significantly higher than that of conventional heating extraction (PCHE, 7.64%). Compared to PCHE, PMEAE and PEAE exhibited higher degree of esterification of 68.43% and 67.89%, respectively, coupled with more highly branched side chains, which was confirmed by Fourier-transform infrared (FTIR) analysis. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) analysis showed that PMEAE and PEAE exhibited superior thermal stability. PEAE and PMEAE owned higher viscosity and superior antioxidant biological activity than PCHE. This study suggested that feijoa pectin by microwave enzyme-assisted or enzyme-assisted extraction contained more branched side chains and had better physicochemical and functional properties.