Pectins from Citrus maxima

Abstract

Pectins from the fruit peel of Citrus maxima (Burm. f.) Merr. or pomelo (Rutaceae) were composed of two main groups: 1) water-soluble pectin (WSP) [high-methoxyl pectin, degree of methoxylation (DM)69.32-78.68%], and 2) oxalate-soluble pectin (OSP) (low-methoxyl pectin, DM21.01-55.41%). Variation of plant cultivar and storing time of the fruits after harvesting did not significantly influence the content, percentage galacturonic acid, DM and neutral-sugar proportion of both WSP and OSP. The contents of WSP and OSP were 8.12-10.87% and 4.89-8.62%, respectively, whereas percentage galacturonic acid of WSP and OSP were 68.31-79.29% and 48.99-74.02%, respectively. Comparison between albedo (inner layer of the peel) and flavedo (outer layer of the peel), the content and percentage galacturonic acid of pectins in albedo were higher. After storing the fruits for 30 days, the molecular weight of WSP in albedo increased from 22-25KDa to 41-50KDa. Infrared (IR) spectra confirmed DM difference between WSP and OSP, and suggested more consistency character of WSP among cultivars and storing times. The proportion of neutral sugars in pectins was not influenced by cultivar and storing time, but it was different between WSP and OSP, and between pectins from albedo and flavedo. © 2009 Informa UK Ltd.