ARS | Publication request: Biosorption properties of citrus peel derived oligogalacturonides, enzyme-modified pectin and peel hydrolysis residues

Submitted to: Proceedings of Florida State Horticultural Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 19, 2008
Publication Date: April 1, 2009
Citation: Cameron, R.G., Luzio, G.A., Widmer, W.W., Iqbal, M. 2008. Biosorption properties of citrus peel derived oligogalacturonides, enzyme-modified pectin and peel hydrolysis residues. Proceedings of Florida State Horticultural Society. 121:311-314.

Interpretive Summary: A citrus processing industry priority is obtaining added value from fruit peel. Approximately one-half of each processed fruit is added to the waste stream. Peel residue mainly is composed of water (~80%), the remaining 20% (solid fraction) consists of pectin, soluble sugars, cellulose, proteins, phenolics, etc. Viewing these constituents in light of exploiting potential functionality and creating added value at the same time as diverting material away from the feed mill or land fill, pectin provides enormous opportunity. To create a new technology centered on pectin structure and concomitant functionality, we have begun exploring methods to precisely engineer pectin structure and correlate it to function. A valuable pectin functionality, resulting from its polyanionic character, is its biosorption capabilities. In the past several years we have developed techniques and methods to enzymatically modify pectin structure, characterize these structural alterations and determine their effect on rheology and calcium sensitivity.

Technical Abstract: Data is presented on the biosorption properties of modified pectins and pectin fragments using lead as a model cation. Samples tested for their sorption capacity are Narrow-Range Size-Classes of galacturonic acid oligomers, well characterized homogalacturonan demethylations series produced at pH 7.5 and 4.5, demethylated commercial pectin, a pectin/peel mixture, a non-calcium sensitive pectin and residue from a peel simultaneous saccharification and fermentation. The greatest Pb sorption capacity (Mean = 373.3 mg ¿ g-1; S.E. = 1.595; p > 0.001) was observed in the Medium DP size-class of galacturonic acid oligomers. A comparison of enzymatically demethylated (blockwise) homogalacturonans indicated that the 60% and 50% DM pectins treated at pH 4.5 had a significantly greater sorption capacity than higher DM or pH 7.5 treated samples. Commercial, demethylated pectin had the highest sorption capacity of all the modified pectins.