Isoelectric precipitation of casein using high-pressure CO2

Gerard W. Hofland, Marco Van Es, Luuk A.M. Van Der Wielen, Geert Jan Witkamp

Research output: Contribution to journalArticlepeer-review

58 Scopus citations


High-pressure CO2 was used as a recyclable acid for the isoelectric precipitation of casein. Measurement of the pH during the high-pressure process allowed the comparison of the process with conventional precipitation using sulfuric acid. A simple model was made up to calculate the pH in complex aqueous solutions pressurized with CO2. It was established that the isoelectric point (pH 4.6) could not be reached with CO2, unless the milk was diluted. Nevertheless, high precipitation yields could be obtained with this process. Still, it was found that the precipitation is mainly caused by the decrease in pH. The removal of calcium phosphate appeared to be complicated, probably because of precipitation of calcium phosphate in the casein-free solutions after the pressure is released.

Original languageEnglish (US)
Pages (from-to)4919-4927
Number of pages9
JournalIndustrial and Engineering Chemistry Research
Issue number12
StatePublished - Dec 1999
Externally publishedYes

ASJC Scopus subject areas

  • General Chemistry
  • General Chemical Engineering
  • Industrial and Manufacturing Engineering


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