2005 Annual Report
This work is relevant to citrus growers and citrus juice processors who will benefit by realizing increased value for their products. The impact of this project for the citrus industry is increased crop value, more competitive U.S. citrus products, and a reduction in biomass pollution and disposal problems. Other customers of the research are industrial manufacturers of building and construction materials, paper additives, and industries requiring materials for waste water remediation that are environmentally friendly. It is also possible that the applications developed by this project to produce new by-products from the citrus waste stream could be applied to other fruit and vegetable processing waste streams rich in polysaccharides, such as those produced by the apple and sugar beet industry. This project is 100% devoted to addressing Component 2 (New Processes, New Uses, and Value-Added Foods and Biobased Products) of NP 306, Quality and Utilization of Agricultural Products. We seek to enhance the value and competitiveness of the U.S. citrus industry by developing new by-products and industrial applications for existing and newly developed citrus by-products through the use of economical, environmentally benign, and efficient processing methods.
4. Scale up on promising pectin modifications with chemicals to provide testing material to industry.
5. Further chemical modification of citrus peel materials and testing of new products.
Year 2 (FY 2006) 1. Further modifications on pectin, using enzymes, acid, base, and crosslinking of resins. 2. Complete studies on disaggregation using proteases and surface-active agents and continue technology transfer.
3. Further structural modification of pectin with PME, accumulation of PME modified pectins, and determination of their functional properties and technology transfer.
4. Scale up of pectin modifications, provide test materials to industry partners.
5. Continue modification of citrus peel and testing and initiate technology transfer.
Year 3 (FY 2007) 1. Continue with resin crosslinking studies and continue technology transfer.
2. Incorporate disaggregation improvements into isolation process and continue technology transfer.
3. Continue determination of pectin structural modifications and functional properties, continue scale up production of modified pectin materials, and provide test materials to industry partners.
4. Optimize modification of citrus peel and testing and initiate technology transfer
Year 4 (FY 2008) 1. Finish technology transfer with ion exchange, polymer, and resin product for industry
2. Finish technology transfer of processes and additive by-products for building products industry
3. Finish determination of functional properties of PME modified pectins and technology transfer
4. Complete physical properties testing of new products and finish technology transfer
Combined use of evaporative and multi-angle light scattering detectors to determine molecular weight and charge of pectin molecules: A new analysis methodology for the study of pectins and other polysaccharides from peel was developed using an evaporative light scattering detector coupled with multi-angle light scattering detector. This new methodology permits molecular weight determination of large molecules under gradient conditions to determine molecular charge and size relationships for extracted pectins. The functional properties of pectins are mostly dependent on the charge and size characteristics of these molecules. Understanding the ionic charge/size properties is essential in the development on new products since these properties control many of the functional properties of pectins in industrial applications.
A method was developed for preparative fractionation of polygalacturonic acid fragments into several weight classes (low, medium, and high degree of polymerization) of polygalacturonic acid.
Three of the four isozymes of PME present in citrus fruit peel have been prepared as monocomponent preparations and characterized for their physical and biochemical properties. Conditions have been described that favor activity of one isoform over the others which will allow for their use in tailoring the structural and functional properties of modified pectin or fruit peel fragments for industrial utilization.
Assay procedure for determination of the major component of citrus peel, pectin, was developed. This will assist in quantitation of this important component as new products and processes are developed for its modification and release from peel. This technique could be of value in all future products involving pectin in citrus peel.
Demonstrated non-calcium sensitive pectins could be isolated from washed orange peel in yields representing approximately 15% on a dry weight basis. This is approximately half of the total available pectin present in the peel. These pectins were extracted under relatively mild reaction conditions which simplify the process and aids in technology transfer.
A scalable process for the conversion of citrus waste sugars and polysaccharides into ethanol for use as a biofuel was developed and demonstrated at the 100 gallon process level. Limonene is also recovered during the process which is another valuable by-product with an already established market and helps make the process economically feasible in addition to reducing concerns about volatile organic emissions from citrus processing plants.
Cameron, R.G., Savary, B.J., Hotchkiss, A.T., Fishman, M.L. 2005. Isolation, characterization and pectin modifying properties of a thermally tolerant pectin methylesterase from valencia oranges. Journal of Agricultural and Food Chemistry. 53:2255-2260.
Luzio, G.A. 2004. Determination of galacturonic acid content of pectin using a microtiter plate assay. Proceedings of Florida State Horticultural Society. 117:416-421.
Cameron, R.G., Grohmann, K. 2004. Mapping demethylated block size and distribution in pectin from citrus processing waste. Subtropical Technology Conference Proceedings. 55:43.
Wilkins, M.R. 2004. Citrus peel ethanol: florida's biofuel for the future. Subtropical Technology Conference Proceedings. 55:40-41.
Savary, B.J., Nunez, A., Cameron, R.G. Mass spectroscopy profiling of tryptic-peptides for identifying pectin methylesterases isolated from valencia orange [(citrus sinensis (l.) osbeck] fruit. Abstract 229TH NATIONAL MEETING, AMERICAN CHEMICAL SOCIETY, SAN DIEGO, CA., March 13-17, 2005. Cell 118.
Luzio, G.A. 2004. Investigation of galacturonic acid colorimetric assay of pectin in citrus peel. Subtropical Technology Conference Proceedings. 55:42.
Cameron, R.G., Luzio, G.A., Grohmann, K., Savary, B.J. 2005. Mode of action of two commercial pectolytic endo-polygalacturonases. National Meeting of Institute of Food Technologists/Food Expo. Paper No. 71B-3.