Extraction optimization and physicochemical properties of pectin from melon peel

•Extraction of pectin from melon (Cucumis melo L.) peel was optimized.•Central composite design was used to model the yield and DE.•Citric acid was identified as the most effective acid for pectin extraction.•Optimum condition for pectin extraction at pH = 1 was 95 °C for 200 min with SSR 10.•Melon peel pectin is classified as low methoxyl pectin.

In this study, acidic extraction (citric acid) was used for the extraction of pectin from melon peel. A central composite design (CCD) was applied to study the effect of temperature (35-95 °C), time (40-200 min), pH (1-3) and solvent to sample ratio (10-50 v/w) on the yield and degree of esterification (DE). The results showed that the yield and DE ranged from 2.87 to 28.98% and 1.33-29.33%, respectively. Also, the highest extraction yield (29.48 ± 1.7%) was obtained under optimal conditions (pH of 1, temperature of 95 °C and ratio of 10 v/w after 200 min). The protein, ash, carbohydrate and galacturonic acid content of pectin obtained under optimal conditions were about 1.5, 3.5, 10 and 48%, respectively. Rheological experiments determined that melon peel pectin dispersions behaved as a weak gel at concentrations of 1%w/v. The emulsifying activity was 35% and also, the emulsion stability was higher at 4 °C than at 23 °C.