abstract
The composition of pomegranate peel, the main by-product during pomegranate processing, and some of the characteristics of the water-soluble pectins were investigated. Four tunisian pomegranate peels were subjected to hot aqueous extractions (86C, 80 min, 20 mM nitric acid). Pomegranate peels yielded between 6.8% and 10.1% pectins. The extracted pectins were low methylated and were characterized by the predominance of homogalacturonan regions. Principal component analysis applied on FT-IR spectraldatainthe regionbetween4000and650 cm1 differentiatedthesamplesaccording totheirdegree of methylation. At pH 3, in the presence of 0.7% pectin, all solutions showed a rapid gel formation with G0 > G00. With decreasing temperature from 90C to 10C, G0 increased to reach a plateau at 10C. The variation in the pectin gel formation between varieties was attributed to difference in pectin characteristics particularly the hydrodynamic volume and the neutral sugar content. 2016 Elsevier Ltd. All rights reserved.