|COOKE, PETER - New Mexico State University|
Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/1/2009
Publication Date: 10/28/2009
Citation: Nunez, A., Fishman, M., Fortis, L.L., Cooke, P.H., Hotchkiss, A.T. 2009. Identification of extensin protein associated with sugar beet pectin. Journal of Agricultural and Food Chemistry. 57:10951-10958.
Interpretive Summary: It is estimated that in the U.S. the sucrose production from sugar beet generate about 2 millions tons of dry sugar beet pulp waste every year. The pulp has low commercial value and consequently, other value-added commercial applications of the pulp are needed for the further utilization of the residue. The pulp has a high content of pectin, which has particular excellent emulsifying properties that are of interest in the food industry. The emulsifying properties have been associated with the presence of a protein, but the protein has not been identified. For the first time, we have identified the protein associated with sugar beet pectin and have linked to the possible role that it plays in the structure of pectin. This work provides new evidence to understand the emulsifying properties of sugar beet pectin and will help in the development of commercial pectin from sugar beet.
Technical Abstract: Several studies have suggest that the emulsifier properties associated with pectin obtained from sugar beet (Beta vulgaries) are due to the presence of a protein–pectin complex. Nevertheless, the identity of the protein has remained elusive. Pectin, extracted from sugar beet pulp by microwave-assisted extraction, and a commercial sample, were both subject to digestion with trypsin. The resulting peptides were separated from the pectin solution by ultra filtration using a MWCO of 3 KDa and analyzed using Matrix Assisted Laser Desorption Ionization with tandem time of flight mass spectrometry. The sequences derived from mass spectrometry analyses of the tryptic peptides are highly consistent with the extensin protein previously reported in sugar beet. The evidence supports the existence of a complex between the pectin and extensin protein. Atomic force microscopy demonstrated that the number of rod-like elements decreased following protease treatment compared to the untreated sample.