A key parameter for a protein to maintain its functional characteristics is the pH environment
to which the protein is subjected. When a protein is close to its isoelectric point, it possesses
low solubility and therefore loses most of its emulsifying ability (Smith and Culbertson,
2000). Ralet and Guéguen (2000) studied the emulsion properties of different potato protein
fractions over pH4–8. The pH range was tested with the addition and absence of NaCl at 1%.
They observed that in an acidic environment in the absence of NaCl, the patatin emulsion was
slightly more stable compared with the emulsion in the presence of NaCl. Moreover, when
the protease inhibitor fraction was examined, it did not have pH dependency