Isoelectric precipitation of soybean protein using carbon dioxide as a volatile acid

Gerard W. Hofland*, Aris De Rijke, Russell Thiering, Luuk A.M. Van Der Wielen, Geert Jan Witkamp

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

51 Scopus citations


A novel process is presented for the isoelectric precipitation of soy protein, using carbon dioxide as a volatile acid. By contacting a soy meal extract with pressurized carbon dioxide, the solution pH was decreased to the isoelectric region of the soy proteins. Complete precipitation of the precipitable soy proteins could be achieved for protein concentrations up to 40 g/l at pressures less than 50 bar. Isoelectric precipitation with a volatile acid enabled accurate control of the solution pH by pressure and eliminated the local pH overshoot, usual in conventional precipitation techniques. The advantage of the improved precipitation control was reflected by the morphology of the precipitate particles. Protein aggregates formed by CO2 were perfectly spherical whereas protein precipitated by sulfuric acid had an irregular morphology. The influence of process variables to control particle size is discussed. (C) 2000 Elsevier Science B.V.

Original languageEnglish (US)
Pages (from-to)357-368
Number of pages12
JournalJournal of Chromatography B: Biomedical Sciences and Applications
Issue number1-2
StatePublished - Jun 23 2000
Externally publishedYes


  • Carbon dioxide
  • Isoelectric precipitation
  • Soy protein

ASJC Scopus subject areas

  • General Chemistry


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