Kosmotropes and chaotropes as they affect functionality of a protein isolate

Influences of kosmotropic and chaotropic anions on functional properties of a protein isolate prepared from African locust bean were investigated. The pH-dependent protein solubility profile showed that solubility was minimal at the isoelectric point of the protein isolate (pH 4.5). At all pHs, protein solutions prepared in chaotropic anions (SCN−, ClO 4 - and I−) had better solubilities than those prepared in kosmotropic anions ( SO 4 2 - , Cl−, I−). Increase in protein solubility followed the Hofmeister series: Na2SO4, <NaCl, <NaBr, NaI,<NaClO4,<NaSCN. Water absorption capacity was maximal in solutions prepared at 0.1 M concentrations and it was reduced when the concentration increased further. Generally, the result indicates that kosmotropic salts had improved water absorption capacity over the chaotropic salts. Both foaming capacity and stability were better in chaotropic salts than in kosmotropic salts. Emulsifying activity and stability were reduced as the concentration of salts in each protein solution increased. Among the various protein solutions, maximal emulsifying activity and stability were observed in protein solutions prepared in NaSCN and protein solution prepared in NaSO4 had the lowest emulsifying properties. Chaotropic salts had better emulsifying properties than had kosmotropic salts and the emulsifying potentials increased according to the Hofmeister series. The result indicates that least gelation concentration increased as the concentration of salts increased and LGC values were lower in chaotropic anions than in kosmotropic anions.