Yield and composition of pectin extracted from Tunisian pomegranate peel

• Pectin was extracted from pomegranate peel using RSM.
• Individual and combined effects of the variables on the yield and Gal A were studied.
• Maximum extraction yield of pectin was obtained at 86 °C for 80 min and pH 1.7.
• The composition of the extracted pectins were determined.
• Pomegranate peel has the potential to be a source of low-methoxy pectins.

A central composite design was employed to determine the influence of extraction conditions on production yield and chemical composition of pectin from pomegranate peels. Response surface methodology (RSM) was used to quantify the integral effect of the three processing parameters (extraction duration, temperature and pH) on yield. A second-order polynomial model was developed for predicting the yield of pomegranate peels pectin based on the composite design. Yields ranged from 6.4 to 11.0 ± 0.2%. Optimal temperature, duration and pH value of the extraction were 86 °C, 80 min and 1.7, respectively. The uronic acid and the total neutral sugar content of the extracted pectins ranged from 377 to 755 mg/g and from 161 to 326 mg/g, respectively. Moreover, the degree of methylation varied with the extraction conditions and the extracted pectins were low methylated. On high pressure size exclusion chromatography (HPSEC), the elution pattern of the acid-extracted pectins showed that severe conditions were associated with lower hydrodynamic volume.