2.3. Modification of durian rind pectin
The pH and temperature modification of DRP was performed according to Nangia-Makker et al. (2002) and Platt and Raz(1992). Initially, DRP was solubilized as a 1.5% solution in distilled water, and its pH was increased to 10.0 with NaOH (3 N), followed. by a 1 h incubation at 50–60 C. Then, it was cooled to room temperature while its pH was adjusted to 3.0 with 3 N HCl and stored overnight. Samples are then precipitated the next day with 95% ethanol and incubated at 20 C for 2 h, filtered, washed with acetone, and dried in a vacuum oven at 25 C for 8 h. The pectin was ground and sieved (mesh no. 60) for further experiments. This pectin was designated as modified durian rind pectin or mDRP.