*4.2.3 Physicochemical analysis*

For moisture content, 1 g of fruit pectin was dried at 105°C for 24 h. Ash content was measured after dry ignition of 1 g of pectin samples (550°C, 6 h) in a muffle furnace. Protein content was determined using the Kjeldahl method (crude protein = N × 6.25). Total carbohydrate content was measured according to the phenol sulfuric acid method. The GalA content was determined using the meta-hydroxydiphenyl method. The DE was measured according to Kazemi et al. [17]. TPC was found on an SP-UV500DB model UV-vis spectrophotometer according to the Folin-Ciocalteu method using a standard curve of gallic acid. TPC was expressed as mg gallic acid equivalent per g of pectin (mg GAE/g pectin). All physicochemical measurements were compared based on the commercial citrus pectin.

Average MW was determined by injection of pectin solution (20–50 μL, 1 mg/ mL) high-performance gel permeation chromatography (HPGPC) using an Ultrahydrogel™ column and a RID4 -10A refractive index detector. For elution, NaNO3 (0.1 M) was used as mobile phase at a flow rate of 1 mL/min and temperature of 35°C. The calculation was based on the calibration curves of dextran standards.
