title: Effect of disulfide interactions and hydrolysis on the thermal aggregation of β-lactoglobulin.
abstract: The roles of sulfhydryl/disulfide interactions and acid/pepsin hydrolysis on β-lactoglobulin (β-lg) thermal aggregation at acidic pH 3.35 and 2 were studied using rheology, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), transmission electron microscopy (TEM), and Western blotting. Pepsin promoted additional hydrolysis compared to the acid-hydrolyzed control sample based on a 12% increase in free amino groups. Hydrolysis with pepsin also resulted in an increase in the apparent viscosity by 2 logs upon heating 8% β-lg solutions at pH 3.35. Seemingly, hydrolysis promoted thermal aggregation of β-lg, correlating well with viscosity increases. Large microgels were observed in heated pepsin hydrolysates using TEM, supporting the increased viscosities of these dispersions. During thermal aggregation (85 °C, 3 h) of β-lg at pH 3.35, beyond the existence of limited disulfide interactions, acid hydrolysis and noncovalent interactions more likely play a crucial role in defining the functionality of acidified powdered modified whey ingredients.
authors.affiliation: Department of Food, Bioprocessing and Nutrition Sciences, Schaub Hall, Dan Allen Drive, North Carolina State University , Raleigh, North Carolina 27695-7624, United States.
authors.forename: Prashant
authors.initials: P
authors.lastname: Mudgal
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Daubert
authors.forename: Debra A
authors.initials: DA
authors.lastname: Clare
authors.forename: E Allen
authors.initials: EA
authors.lastname: Foegeding
mesh_terms: D004220:Disulfides / Q000737:chemistry*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007782:Lactoglobulins / Q000737:chemistry* / Q000378:metabolism; D010434:Pepsin A / Q000378:metabolism; D012996:Solutions; D014783:Viscosity
chemical_list: D004220:Disulfides; D007782:Lactoglobulins; D012996:Solutions; D010434:Pepsin A