|Grohmann, Karel - RETIRED USDA|
Submitted to: Subtropical Technology Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: September 16, 2003
Publication Date: October 16, 2003
Citation: Cameron, R.G., Kauffman, S.W., Grohmann, K. 2003. Modification, separation and detection of oligogalacturonides. Subtropical Technology Conference Proceedings. 54:40. Technical Abstract: Fruit peel, containing 300 - 400 pounds of pectin per ton, is the major component of the citrus juice processing waste stream. Pectin is a complex polysaccharide in which galacturonic acid (GA) comprises 80 - 90% of the dry weight. The majority of the GA residues are located in linear homogalacturonan regions and may be methylated at the C6 position. The functional properties of pectin are largely dependent on the fraction of GA residues that are methylated and their distribution along the homogalacturonan oligomer. In order to map pectin fine structure (i.e., determine the size and distribution of methylated and demethylated GA blocks) and establish the relationship between fine structure and functional properties, it is necessary to produce, separate, detect and quantify oligogalacturonic acid fragments. We have developed chemical, enzymatic and chromatographic methods to accomplish these tasks. Data will be presented on the preparation, separation, identification and quantification of oligogalacturonides produced by either enzymatic or chemical hydrolysis. Results from ion exchange (IEC) and size exclusion chromatography (SEC) will be included. The development of methods compatible with an evaporative light scattering detector (ELSD) have enabled us to accurately estimate masses associated with peak areas after IEC and SEC. Incorporating a post-column addition of potassium carbonate to a near neutral anion exchange buffer system has allowed us to use integrated amperometry to detect oligogalacturonides ranging in size from one to greater than 10 GA residues. With an ELSD we can separate and detect oligomers over 70 GA residues in length, a 60% increase over previously published methods. Results from SEC coupled to either an ELSD or refractive index detector also will be presented.