Available at: http://digitalcommons.calpoly.edu/theses/1203
Date of Award
MS in Agriculture - Dairy Products Technology
Whey protein, containing predominately b-Lactoglobulin (b-LG), is a popular choice among consumers looking for an excellent protein source. Likewise, fat is a natural component in milk and dairy products. Lipids are packaged within a membrane called the Milk Fat Globule Membrane (MFGM). The MGFM contains a variety of lipids and proteins. Although b-LG has been extensively characterized, the function of the protein is largely unknown. The objectives of this study were to assess the enzymatics of b-LG in an isolated system, evaluate the propensity of b-LG to bind to MFGM, determine the effects of temperature and fat extraction method on the conformation of b-LG, assess the antigenicity of b-LG in an isolated system, and determine the effects of temperature and fat extraction method on the antigenicity of b-LG peptides. Time course hydrolysis of b-LG reveled only slight differences in cleavage rate. A Mass Spectrometry method was developed to detect b-LG peptides. Whey Protein Isolate (WPI) digests in an isolated system yielded on average 8.67 ± 0.33 unique peptides and a protein sequence coverage of 43.67 % ± 1.33. When WPI was a component in a complex system of washed cream, it was found that there was an interaction between temperature and fat extraction method (P=0.001) in the individual peptide release. However, it was found that the total number of peptides released was dependent on the extraction method (P2resulted in a decrease in antigenicity. Investigating the binding complex of b-LG and MFGM, utilizing a sensitive analytical instrument and technique, illustrates how b-LG peptides can be accurately detected, quantified, and how conformational changes within the structure protein can be used to infer information regarding the function of the protein.