Advertisement

Identification Tests for Proteins (Casein and Albumin)

  • Aakanchha Jain
  • Richa Jain
  • Sourabh Jain
Protocol
  • 80 Downloads
Part of the Springer Protocols Handbooks book series (SPH)

Abstract

Casein, like proteins, is made up of many hundreds of individual amino acids. Each may have a positive or a negative charge, depending on the pH of the [milk] system. At some pH value, all the positive charges and all the negative charges on the [casein] protein will be in balance, so that the net charge on the protein will be zero. That pH value is known as the isoelectric point (IEP) of the protein and is generally the pH at which the protein is least soluble. For casein, the IEP is approximately 4.6, and it is the pH value at which acid casein is precipitated. In milk, which has a pH of about 6.6, the casein micelles have a net negative charge and are quite stable. During the addition of acid to milk, the negative charges on the outer surface of the micelle are neutralized (the phosphate groups are protonated), and the neutral protein precipitates.

Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature 2020

Authors and Affiliations

  • Aakanchha Jain
    • 1
  • Richa Jain
    • 2
  • Sourabh Jain
    • 3
  1. 1.Bhagyoday Tirth Pharmacy CollegeSagarIndia
  2. 2.Centre for Scientific Research and DevelopmentPeople’s UniversityBhopalIndia
  3. 3.Sagar Institute of Pharmaceutical SciencesSagarIndia

Personalised recommendations