A new approach for pectin extraction: Electromagnetic induction heating

Electromagnetic induction (EMI) and conventional (CV) heating have been employed to extract pectin from citrange (Citrus sinensis × Poncirus trifoliata) albedos under the same extraction conditions (pH 1.2, temperature 80 °C and extraction time 90 min). The electromagnetic induction heating process was investigated at different extraction times (10, 20, 30, 40, 50, 60 and 90 min) and at different power levels. The high pectin yield obtained with this process was found to be 29% (w/w) of dried albedos, which was almost equal to that found using conventional heating (24% (w/w)). However, a considerable reduction in the extraction time was observed. It was found that 30 min of electromagnetic induction extraction of pectin from dried albedos yielded the same amount (24% (w/w)) of pectin obtained by conventional heating process for 90 min. Also, the electromagnetic induction heating at higher power and for only 2.09 min gave half the amount of pectin extracted by conventional heating for 90 min. Moreover, it was found that both extracted pectins showed almost similar compositions and physicochemical properties, presenting a galacturonic acid content of 29.10–29.40% and an esterification degree of 61.00–62.50%. The average molecular weight for both pectins extracted by EMI and CV heating ranged from 0.84 × 105 to 1.63 × 105. Hence, the electromagnetic induction heating can be suggested as a promising method for the extraction of pectin from citrange albedos at a short time, with a remarkable yield and keeping the composition and the physicochemical properties of the pectin unchanged.