Pectin from muskmelon (Cucumis melo var. reticulatus) peels: extraction optimization and physicochemical properties

Abstract

Pectin derived from plant waste sources is currently focused as an economical and eco-friendly approach. Optimization of pectin extraction from muskmelon peel by response surface methodology (RSM) was investigated in this study. Box-Behnken Design (BBD) was used to identify the optimal level of the extraction variables such as time, pH and temperature. A second-order model equation for pectin extraction was obtained from multiple regression analysis of experimental data with the correlation coefficient (R 2 ) value of 0.92. ANOVA results showed that linear effect of temperature and combined effect of pH with temperature were found significant for pectin extraction from muskmelon peel. Validation results had good agreement with the predicted results. Pectin extracted from muskmelon peel was classed as high methoxy pectin with the equivalent weight of 384.5 g/mol. Non-newtonian pseudoplastic flow behaviour was observed for muskmelon pectin from the viscosity studies.

Environmentally Friendly Hydrothermal Processing of Melon by-Products for the Recovery of Bioactive Pectic-Oligosaccharides

“…Both FTIR spectra ( Figure 5) show similar bands to those of pectins found in the bibliography, especially the purified pectin with more intense peaks [19,20,31,70,72,73]. The peak at 3200-3500 cm −1 corresponds to OH stretching as a result of hydrogen bonding in pectin [19,31,71].…”

“…As shown in Table 2 , the pectin yield was 16.59 g/100 g WIS, in dry weight, with a galacturonic acid content of 55.41% (91.23% of the galacturonic acid present in the original liquor). When comparing with the citric acid extraction, greatly differing melon peel pectin yields (3.24–29.48%) and lower galacturonic acid contents (indicating lower pectin purity) (47–48%) were reported [ 19 , 20 ]. Concerning similar raw materials, several autohydrolysis studies found a wide range in the galacturonic acid content of the obtained pectin, with higher values for the pomelo peels (76.62%) [ 54 ] and lower for apple pomace (48%) [ 55 ], both of which presented moderately higher pectin yields than this work (19.6 and 17.55%, respectively).…”

“…The patterns between 1200 and 800 cm −1 represent the "finger print" area, which is unique to a compound, making its interpretation a complicated matter [19,73]. the COO-functional group in pectin [20]. The patterns between 1200 and 800 cm −1 represent the "finger print" area, which is unique to a compound, making its interpretation a complicated matter [19,73].…”

“…Melon by-products have high contents of polysaccharides and minerals, as well as bioactive compounds with antioxidant activity, including phenolic compounds such as flavonoids and phenolic acids, with important applications in several food and pharmaceutical industries [ 14 , 15 , 16 , 17 , 18 ]. One of the main components of the melon peel is pectin [ 19 , 20 ], a complex heteropolysaccharide found in the plant cell walls of many agro-industrial by-products, consisting of a backbone of galacturonic acid (GalA) with alternating ‘smooth’ and ‘hairy’ regions [ 21 , 22 ]. Homogalacturonans (HGs) represent the smooth regions, which are composed of GalA linked by α-(1,4) glycosidic bonds and constitute about 65% of the pectin, while rhamnogalacturonans (RG-I and RG-II) form the hairy region, with RG-I being the main branched structure of pectin, constituting 20–35% of the molecule [ 21 ].…”

“…However, the literature concerning extraction technologies for the production of bioactive compounds from melon by-products is limited. For instance, the extraction of melon peel pectin with citric acid has been optimized recently by Muthukumaran et al [ 20 ]. In another study, Raji et al [ 19 ] assessed the influence of several acids on the extraction of melon peel pectin, obtaining the highest pectin yield (29%) with citric acid.…”