Influence of the drying operating conditions on the chemical characteristics of the citric acid extracted pectins from 'pera' sweet orange (Citrus sinensis L. Osbeck) albedo and flavedo

In this work, the effect of the process conditions used for the separately drying of milled albedo and flavedo on the chemical characteristics of the pectins extracted in a second step from 'Pera' sweet orange (Citrus sinensis L. Osbeck) by using citric acid were studied. The highest yield value obtained was 38.21% w/w for dried albedo (Pectin-A) at 70 °C and 0.1 m s−1 of air velocity. The analyses of Fourier transform infrared spectroscopy (FTIR) shows that both Pectin-A and Pectin-F (Flavedo) are characterized as high methoxyl pectin (HM) (DE > 50%). The pectin was assessed for its molecular weight (MW) by the technique of gel permeation chromatography (GPC) and the results of MW varied between 337.41-606.85 kDa for Pectin-A and 487.92-1702.00 kDa for Pectin-F. The quality of pectin, determined by the galacturonic acid (AGA), has the highest value of 93.64% for Pectin-A.