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Hydrophobicity, Solubility, and Emulsifying Properties of Enzyme‐Modified Rice Endosperm Protein
Author(s) -
Paraman Ilankovan,
Hettiarachchy N. S.,
Schaefer Christian,
Beck Markus I.
Publication year - 2007
Publication title -
cereal chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.558
H-Index - 100
eISSN - 1943-3638
pISSN - 0009-0352
DOI - 10.1094/cchem-84-4-0343
Subject(s) - chemistry , solubility , endosperm , hydrolysate , hydrolysis , enzyme , proteases , chromatography , enzymatic hydrolysis , storage protein , biochemistry , organic chemistry , gene
Rice endosperm protein was modified to enhance solubility and emulsifying properties by controlled enzymatic hydrolysis. The optimum degree of hydrolysis (DH) was determined for acid, neutral, and alkaline type proteases. Solubility and emulsifying properties of the hydrolysates were compared and correlated with DH and surface hydrophobicity. DH was positively associated with solubility of resulting protein hydrolysate regardless of the hydrolyzing enzyme, but enzyme specificity and DH interactively determined the emulsifying properties of the protein hydrolysate. The optimum DH was 6–10% for good emulsifying properties of rice protein, depending on enzyme specificity. High hydrophobic and sulfhydryl disulfide (SH‐SS) interactions contributed to protein insolubility even at high DH. The exposure of buried hydrophobic regions of protein that accompanied high‐temperature enzyme inactivation promoted aggregation and cross‐linking of partially hydrolyzed proteins, thus decreasing the solubility and emulsifying properties of the resulting hydrolysate. Due to the highly insoluble nature of rice protein, surface hydrophobicity was not a reliable indicator for predicting protein solubility and emulsifying properties. Solubility and molecular flexibility are the essential factors in achieving good emulsifying properties of rice endosperm protein isolates.