Physicochemical characterization of pectin extracted from mandarin peels using novel electromagnetic heat

A novel electromagnetic heat extraction method was presented, whereby mandarin peels residue solution was located in a winding coil subjected to an oscillating magnetic field, and the pectin was extracted under appropriate conditions. Numerical relationships between applied magnetic field and induced electric field (IEF) in the extraction process were elaborated. The results showed that the induced current density, IEF and terminal temperature increased with increasing magnetic field. The maximum current density of 0.35 A/cm corresponds to the highest terminal temperature of 84.6 °C and IEF intensity of 26.6 V/cm. When magnetic field intensity was 1.39 T and the extraction time was 15 min, the maximum yield of pectin reached 9.16 %. In addition, all treatments impacted the ash content, protein content, water-holding capacity (WHC), and oil-holding capacity (OHC) of the obtained pectin. The pectin extracted by electromagnetic heat had the lowest DE value of 71.3 % with 126.55 kDa molecular weight, while the GalA content was at the highest level of 76.18 %. After different treatments, the composition of pectin monosaccharides changed, but there were slight differences in the composition of pectin polysaccharides. Moreover, the electromagnetic heat extracted pectin had light color and an obvious surface fragmentation of the peel residue.