2.2. Extraction procedure
MAE of pectin was performed in an ordinary household microwave oven (LG, MH-3948 WB) at working frequency of 2450 MHz with adjustable microwave power. About 5 g of dried dragon fruit peel powder was weighed and placed into a 1000 mlPyrex beaker. The beaker was placed in the middle of the oven over a rotating dish and was exposed to microwave radiation at different powers for the selected temperature and solid–liquid ratio. After microwave heating, the mixture in the Pyrex beaker was allowed to cool down and filtered using filter paper (Whatman no-1). The filtered extract was centrifuged and the supernatant was precipitated with an equal volume of 95% (v/v) ethanol. Each of the extraction conditions was carried out in triplicates.