Extraction and Characterization of Pectin from Grapefruit Peels

The present study was focused on the potential of red and white grapefruit peel as a source of pectin. Grapefruit peels were treated with 95% alcohol and the obtained alcohol-insoluble solids (AIS) were subjected to a sequential extraction with hot distilled water and hot 0.5% HCl. Comparative investigations were carried out with purified commercial citrus pectin. Chemical and physicochemical characterization of all pectin was accomplished. The yield of grapefruit peel pectin was 25% (dwb) It was found that pectin of the two types of grapefruit peels were similar in anhydrouronic acid content (AU 60.95%). The grapefruit peel pectin for the red and white differed in their degree of esterification (DM 51.24-55.01%) and 50.848% for corresponding citrus pectin. Both grapefruit peel pectin were higher in their methoxyl content 8.875% for the red and 7.542% for the white, while corresponding citrus pectin was 6.798%. The acetyl content for the white grapefruit peel pectin was 1.634% and for the red was 0.55%, lower in comparison with the corresponding citrus pectin of 0.624. The grapefruit peel pectin contained L-arabinose, D-galactose, L-rhamnose and D-xylose. Gel-forming property of grapefruit peel pectin was of good quality similar to commercial pectin.