Extraction optimization and physicochemical properties of high methoxyl pectin from Ananas comosus peel using microwave-assisted approach

Food and agricultural wastes have led to environmental and landfill issues. Nonetheless, biowastes can be converted into valuable bioproducts, such as pectin. Hence, this study investigated microwave-assisted extraction (MAE) optimisation to extract pectin from pineapple ( Ananas comosus ) peel. Microwave power (400–600 W), pH (1.5–2.5), and solid-to-liquid (S/L) ratio (1:10–1:30 w/v) were applied to optimise pineapple peel pectin (PPP) extraction, as well as to determine the interaction effects on pectin yield and anhydrouronic acid (AUA) content using Box–Behnken Design (BBD). The highest yields of pectin (2.43 ± 0.03%) and AUA content (54.61 ± 0.21%) were achieved at optimised conditions (600 W, pH 1.52, and 1:10 g/mL of S/L ratio), which were 35.75% and 7.93% higher than their values prior to optimisation, respectively. The PPP displayed Newtonian behavior at low concentrations (0.1, 0.5, and 1.0% w/v), but showed pseudoplastic flow behavior at a higher concentration (2.0% w/v). The PPP viscosity was temperature-dependent, as its apparent viscosity gradually decreased with temperature increment from 25 to 75 °C with increasing shear rate. The PPP emulsion stability improved by 1.06- and 1.12-fold after 30 days of storage at 4 and 25 °C, respectively, in comparison to commercial pectin. The MAE method enhanced the pectin yield by 21.5% than the conventional heating technique. The MAE qualifies as an alternative for pectin extraction from pineapple peel, as it demands less solvent and shorter extraction time.