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

Submitted to: Florida State Horticultural Society Meeting
Publication Type: Abstract Only
Publication Acceptance Date: April 5, 2008
Publication Date: April 23, 2008
Citation: Cameron, R.G., Luzio, G.A., Widmer, W.W. 2008. Biosorption properties of citrus peel derived oligogalacturonides, enzyme-modified pectin and peel hydrolysis residues. Florida State Horticultural Society Meeting. Paper No. HP23.

Technical Abstract: 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. Here we present data on the biosorption properties of modified pectins and pectin fragments using lead as model cation. The greatest Pbsorption 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% DE pectins treated at pH 4.5 had a significantly greater sorption capacity than higher DE or pH 7.5 treated samples. Calcium-sensitive pectin released from peel fragments had higher sorption capacity than non-calcium-sensitive pectin or peel hydrolysate.