2.4.1. Gel Permeation Chromatography (GPC)

Gel permeation chromatography was performed on pectin extracted at different times or acidic contents. The analysis was carried out using a GPC Max Viscotek (Malvern, UK) Phenomenex (Torrance, CA, USA) system equipped with a TDA 305 detector (Refractive Index, Low Angle Light Scattering, Right Angle Light Scattering and Viscometer) and UV detector. We used a pre-column TSK PW_XL and TSK Gel GMPWXL. All the samples were dissolved at 2 mg/mL concentration and eluted in MilliQ water containing 0.2% NaN₃ and 0.1 M NaNO₃. After complete dissolution, samples were filtered through membranes of 0.22 μm porosity. The injection volume was 100 μL, and the flow rate was 0.6 mL/min. The chosen method of analysis was triple point, calibrated with a PEO standard, provided by Viscotek, with a narrow molecular weight distribution. The measurements, performed at 40 °C according to the temperatures of the columns and detectors, ran for 60 min in triplicate.