Modification of the solubility of sunflower protein isolates by superlimited proteolysis

Abstract

The modification of slightly soluble sunflower protein isolates by superlimited proteolysis (-0.1 % splitting of the peptide bonds) raises 1 S-2-fold their solubility in neutral medium. The modified preparations may be isolated by isoelectric precipitation with a yield of 95-98 % and became capable to form thermotropic gels.The yields of the isolates obtained from industrial solvent cake are lower (80-82%). The expenditure of proteinase is one order lower than in the usually employed methods of limited proteolysis and the duration of the process is several times lower.

Thermal Gelation of Trypsin Hydrolysates of Sunflower Proteins: Effect of pH, Protein Concentration, and Hydrolysis Degree

“…In seed storage proteins, a general structural disruption and a marked increase of interfacial area and charged groups exposed to the aqueous environment are to be expected from such a limited enzymatic activity. This must in turn increase solubility, as it had been previously shown for sunflower proteins by a number of authors (Kabirullah and Wills, 1981;Jones and Tung, 1983;Bulmaga et al, 1989b) and as it is confirmed in Figure 2. According to Bulmaga et al (1989b), this partial proteolysis splits from the C-terminal sequence of the R chains of the 11S globulin short peptides rich in dibasic amino acids adjacent to a glutamic and aspartic acid rich sequence.…”

“…This must in turn increase solubility, as it had been previously shown for sunflower proteins by a number of authors (Kabirullah and Wills, 1981;Jones and Tung, 1983;Bulmaga et al, 1989b) and as it is confirmed in Figure 2. According to Bulmaga et al (1989b), this partial proteolysis splits from the C-terminal sequence of the R chains of the 11S globulin short peptides rich in dibasic amino acids adjacent to a glutamic and aspartic acid rich sequence. Therefore, it has to increase the net charge of the globulins at pHs above the isoelectric point.…”

Sunflower proteins: overview of their physicochemical, structural and functional properties

“…So far, the gel‐forming properties of sunflower proteins have been found to be poor, although proteolysis was successful in improving gelation, hence making it possible to obtain strong heat‐induced gels 22, 72, 89, 178, 185, 189–191. Even though sunflower protein dispersions seem to form slurries with high viscosity, they form an irregular structure with a foamy appearance 26, 158, 185.…”

“…Plant protein functionality has been positively modified by proteolysis 39, 167, 205, 206. In various studies21, 174, 189, 207–209 the solubility and surface activity of sunflower protein preparations were significantly improved after hydrolysis. Therefore the use of hydrolysis extends the functionality perspectives of sunflower protein preparations.…”