title: Effect of the high-pressure-release phase on the protein composition of the soluble milk fraction.
abstract: This paper describes a study on the influence of the high-pressure-release rate on the protein distribution between the soluble and colloidal fractions of milk. Skim milk, without or with sulfhydryl-blocking agents, was pressure treated at 250 and 350 MPa for 5 to 15 min at 25 °C, applying different pressure-release rates (pressure-release times between 0.07 to 10 min). The liberation of caseins to the soluble phase and the denaturation of whey proteins were assessed. A significantly higher increase in the content of soluble casein took place during the pressure-release phase as compared with a pressure-holding phase. Denaturation of β-lactoglobulin mainly took place by -SH-S-S exchange reactions during the holding phase. The present results, thus, show a negligible influence of whey proteins on the increase in the content of nonsedimentable casein in pressure-treated milk and provide evidence for the importance of the pressure-release rate in this process, so that the slower the pressure release rate, the higher the level of soluble casein.
authors.affiliation: Instituto de Investigación en Ciencias de la Alimentación (CIAL), CSIC-UAM, 28049 Madrid, Spain.
authors.forename: F I
authors.initials: FI
authors.lastname: Bravo
authors.forename: E
authors.initials: E
authors.lastname: Molina
authors.forename: R
authors.initials: R
authors.lastname: López-Fandiño
mesh_terms: D000818:Animals; D002364:Caseins / Q000032:analysis; D002417:Cattle; D003102:Colloids / Q000032:analysis; D019075:Electrophoresis, Capillary; D005511:Food Handling / Q000379:methods*; D063427:Food Quality; D006863:Hydrogen-Ion Concentration; D008892:Milk / Q000737:chemistry* / Q000592:standards; D008894:Milk Proteins / Q000032:analysis*; D011312:Pressure; D013997:Time Factors
chemical_list: D002364:Caseins; D003102:Colloids; D008894:Milk Proteins