**2. Materials and methods**

#### **2.1 Orange peel samples**

The orange peel samples used to extract pectin were kindly provided by the Migros supermarket in Limmatplatz, Zürich (Switzerland) on February 07, 2022. The orange peels were produced as a by-product of orange juice production. They were frozen in plastic bags for 2 days at - 20°C and then freeze-dried for 2 days in a freeze dryer (Labconco FreeZone 4.5 Liter - 50°C Benchtop Freeze Dryer; Kansas City, US). Due to moisture after freeze-drying, the samples were cut into pieces with a diameter of 3 cm and were thoroughly dried in an oven at 70°C for 2 days. The dried orange peel pieces were shredded in a crusher (Durabase Migros; Zürich, Switzerland) and ground with a pestle and mortar. Prior to the pectin extractions, the moisture content was measured for 30 min at 120°C with a halogen moisture analyzer (Mettler Toledo HE53; Greifensee, Switzerland).
