Changes in physico-chemical properties of pectin from jelly fig (Ficus awkeotsang Makino) seeds during extraction and gelling

Degree of esterification of pectin from jelly fig (Ficus awkeotsang Makino) achene seeds and the pH value decreased rapidly during extraction, while apparent reduction of free, calcium content in the pectin extract was observed at the gelling stage. Compared to those of the native pectin, total ester linkages and methyl ester linkages of pectin extract decreased, and the bound calcium content increased during pectin gelling. However, non-methyl ester linkages (the difference between the total ester linkage and the methyl ester linkage) increased by approximately 40% during pectin gelling, revealing esterification reaction between C-6 carboxyl groups and hydroxyl groups in the presence of pectinesterase. Scanning electron microscopy showed that pectin fragments from jelly curds were large with flake-like structure, while those from hot (85degreesC) ethanol-treated achenes were small and porous. (C) 2002 Elsevier Science Ltd. All rights reserved.