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ARS Home » Northeast Area » Wyndmoor, Pennsylvania » Eastern Regional Research Center » Dairy and Functional Foods Research » Research » Publications at this Location » Publication #301303

Title: Characterization of the global structure of low methoxyl pectin in solution

item Fishman, Marshall
item Chau, Hoa - Rose
item Qi, Phoebe
item Hotchkiss, Arland
item Garcia, Rafael
item COOKE, PETER - New Mexico State University

Submitted to: Food Hydrocolloids
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/22/2014
Publication Date: 4/1/2015
Citation: Fishman, M., Chau, H.K., Qi, P.X., Hotchkiss, A.T., Garcia, R.A., Cooke, P.H. 2015. Characterization of the global structure of low methoxyl pectin in solution. Food Hydrocolloids Journal. 46:153-159. DOI 10.10.1016/j.foodhyd.2014.12.021.

Interpretive Summary: The need to increase utilization of low valued co-products derived from the processing of fruit has prompted us to investigate the structure of low methoxyl pectin (LMP). Pectin is a polysaccharide found in orange peels. In this work we examine the effect of added sugar, nitrogen and endogenous protein on the functional properties of pectin. This research should be of help to fruit growers and processors by increasing the demand and value of their by-products without increasing the cost of the basic commodity to the consumer.

Technical Abstract: Low methoxyl citrus pectin (LMP) and amidated low methoxyl pectin (LMAP) were characterized by high performance size exclusion chromatography (HPSEC) with online light scattering (LS), intrinsic viscosity ('w), differential refractive index (dRI) and ultra violet detection (UV), by amino acid analysis (AAA) and by atomic force microscopy (AFM). HPSEC revealed that weight average molar mass (Mw) ranged from about 103-288x103 Daltons, ('w) 2.69-4.30 dL/g, radius of gyration (Rgz) 28.6 nm and hydrated radius (Rhzv) 26.3-41.8 nm. The presence of phenylalanine and tyrosine residues as shown by the UV absorbance at 278 nm in the high molar mass range is indicative of protein or fragments thereof which are associated with low methoxyl pectin derived from citrus fruit. This and earlier AFM images indicate that high and low methoxyl pectin form network structures in aqueous solution. Also, in this study, AFM images, Mw and 'w values for LMP and LMAP indicate that little or no added sugar is bound.