Submitted to: Carbohydrate Polymers
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/24/2014
Publication Date: 3/11/2014
Publication URL: http://handle.nal.usda.gov/10113/60314
Citation: Qi, P.X., Chau, H.K., Fishman, M., Wickham, E.D., Hotchkiss, A.T. 2014. Investigating molecular interactions between beta-lactoglobulin and sugar beet pectin by multi-detection HPSEC. Carbohydrate Polymers. 107:198-208.
Interpretive Summary: Milk proteins are often used as emulsifiers (agents that can help prevent oil and water from separating) whereas polysaccharides (long chains of carbohydrates), are used as thickeners and gelling agents in a variety of food products ranging from mayonnaise to ice cream. Combining milk proteins and polysaccharides may result in new food ingredients with enhanced properties, compared to the single protein or polysaccharide, that are especially useful for improving the nutritional value, textural properties and stability of foods. However, formulations of these ingredients need to be carefully controlled on a molecular level in order to achieve the desired properties. Research on the interaction between a whey protein, one of the major milk proteins, and sugar beet pectin, one of the most versatile polysaccharides, demonstrated that pre-heating the protein and pectin separately before combining is a good way to facilitate binding between the two biopolymers. This study helped to advance our understanding of the interaction between milk proteins and pectin, which can be beneficial to improve foods and beverages and design new ones.
Technical Abstract: Molecular interaction between beta-lactoglobulin (beta-LG) and beta-sugar beet pectin (beta-SBP), both by direct mixing and by thermal treatment prior to mixing at pH 6.75 and low ionic strength (50 mM) was studied using High Performance Size Exclusion Chromatography (HPSEC). The analysis of the hydrodynamic properties of biopolymer fractions revealed interaction between beta-LG and beta-SBP occurred when combined at physiological relevant conditions, and led to the formation of large molecular weight complexes. When the separately pre-heated components were mixed, the majority of beta-LG molecules that existed as aggregated oligomers (due to heat treatment) underwent dissociation to produce smaller oligomers and form larger complex (with beta-SBP). In addition, the results also demonstrated, for the first time to our knowledge, possible existence of small amount (<1%) of non-covalently bound feruloyl moieties in beta-SBP that displayed stronger binding affinity to beta-LG than to beta-SBP.