Lactic acid-mediated isolation of alpha-, beta- and kappa-casein fractions by isoelectric precipitation coupled with cold extraction from defatted cow milk

Abstract

The present study focused on the isolation of individual caseins (α, β and κ) from defatted cow's milk using lactic acid-mediated isoelectric precipitation coupled with cold extraction technique, followed by purification using sucrose-based density gradient centrifugation method. In vitro characterisation of the isolated casein fractions confirmed preservation of micellar morphology throughout the experimental conditions with anionic surface charge and wider particle size range. The RP-HPLC analysis showed a peak at retention time of 25.13 min and 27.84 min for α-casein and β-casein, respectively. Results confirmed isolation of pure casein fractions from cow's milk which could serve as a rich source of bioactive peptides for nutraceutical/pharmaceutical applications.