Pectin extracted from apple pomace and citrus peel by subcritical water

Subcritical water was used to extract pectin from citrus peel and apple pomace, in which the effect of extraction temperature on properties of the pectins was investigated. The maximum yield of citrus peel pectin (CPP) and apple pomace pectin (APP) were 21.95% and 16.68% respectively. No significant differences were found in FTIR spectra of CPP and APP. According to DSC analysis, the endothermic property of pectin was affected by extraction temperature while the exothermic property of pectin was only affected by its constituents and raw material. The pectin solutions exhibited shear-thinning properties and tended to be more elastic (G' > G) with frequency increase according to rheological analysis, which was also reflected in hydrogel analysis. Moreover, both CPP and APP scavenged more than 60% DPPH radical and 80% ABTS radical in vitro and the highest proliferation inhibition rates of colon cancer cell HT-29 by CPP and APP were 76.45% and 45.23% respectively. (C) 2013 Elsevier Ltd. All rights reserved.