The Effect of pH and NaCl Levels on the Physicochemical and Emulsifying Properties of a Cruciferin Protein Isolate

摘要

The influence of pH (3.0, 5.0, and 7.0) and ionic strength (0, 50, 100 mM NaCl) on the physicochemical and emulsifying properties of a cruciferin-rich protein isolate (CPI) was investigated. Surface charge on the CPI was found to substantially reduced in the presence of NaCl. Surface hydrophobicity was found to be the lowest for CPI at pH 7.0 with 100 mM NaCl, and highest at pH 3.0 without NaCl. Solubility was found to be lowest at pH 5.0 and 7.0 without NaCl (＜20 %), however greatly improved for all other pH and NaCl conditions (＞80 %). Interfacial tension was found to be lowest at 10-11 mN/m for pH 5.0-0 mM NaCl and pH 7.0-50/100 mM NaCl, whereas under all other conditions interfacial tension was higher (15+ mN/m). Overall, NaCl has no effect on EAI at pH 3.0 where it ranged between 18.8 and 19.4 m~2/g. At pH 5.0, EAI decreased from 21.1 to 12.8 m~2/g as NaCl levels increased from 0 to 100 mM. At pH 7.0, EAI values were found to decrease from 14.9 to 5.2 m~2/g as NaCl levels were raised from 0 to 100 mM. Overall, ESI was reduced with the addition of NaCl from ～15.7 min at 0 mM NaCl to ～11.6 min and ～12.0 min for the 50 and 100 mM NaCl levels, respectively.