M. Osman, Y. Ishigami, K. Furusawa, and H. Holmsen
[J. Jpn. Oil Chem. Soc., Vol.46, No.7, pp.741-746, 1997]

It was shown that the salt and hard water tolerance, and precipitation phase boundary behavior of spiculisporic acid salts were better than monobasic fatty acid soaps (Table 1). It was demonstrated that spiculisporic acid salts showed considerable surface activities even in the presence of sodium and Ca²⁺ in spite of anionic surfactants. These characteristics and the significant difference of precipitation phase boundary may be attributed to the difference of the hydrophilicity caused by carboxylic, carboxylate, and lactone moieties due to the extent of neutralization or saponification degrees of spiculisporic acid to mono-, di-, to tri-sodium salt.