Journal of Oil & Fat Industries
The 2S and 12S proteins of rapeseed were isolated and subsequently hydrolyzed by pepsin or a combination of pepsin plus trypsin.
The resulting hydrolysates had a 15% degree of hydrolysis and were purified by gel filtration chromatography in order to obtain
homogeneous peptide fractions. Three major fractions, having an average peptide chain length of 7.5–11 amino acids, were recovered.
Purified peptide fractions were acylated with butyric anhydride and sulfamidated with p-toluenesulfonyl chloride. The degree of modification was always higher than 90%. Emulsifying and foaming properties of native
and chemically modified peptides were studied and compared to those of sodium dodecyl sulfate (SDS) as standard. A peptide
fraction from the 15% hydrolysis of the 12S protein exhibited the best foaming properties. After sulfamidation, this peptide
fraction showed a foam formation similar to that of SDS. Whereas the attachment of toluene groups generally improved the surface
properties, the incorporation of an aliphatic chain of four atoms of carbon was detrimental in most of the cases. On the other
hand, none of the native or hydrophobized peptide fractions was able to form a stable emulsion.