Pumpkin seed protein isolate (PSPI) was enzymatically hydrolysed by pepsin to
obtain pumpkin seed protein hydrolysate, PSPH. Investigation on solubility,
interfacial and emulsifying properties of both PSPI and PSPH was conducted
under different conditions of pH (3-8) and ionic strength (0-1 mol/dm3 NaCl).
PSPI had the lowest solubility, i.e. isoelectric point (pI), at pH 5. PSPH
had higher solubility than PSPI over whole range of pH and ionic strengths
tested. Decrease in surface and interfacial tension evidenced that both PSPI
and PSPH adsorb at air/protein solution and oil/protein solution interface.
Emulsions (20 % oil in water) stabilized by 1 g/100cm3 PSPI or PSPH solution
were prepared at pH 3, 5 and 8 and ionic strength of 0 and 0.5 mol/dm3 NaCl.
PSPH stabilized emulsions from coalescence at all pH and ionic strengths
tested. PSPI was able to stabilize emulsions at pH 3 and 0 mol/dm3 NaCl, and
at pH 8 regardless of ionic strength, while emulsions at pH 5 and both 0 and
0.5 mol/dm3 NaCl and at pH 3 when ionic strength was increased separated to
oil and serum layer immediately after preparation. All emulsions were
susceptible to creaming instability.
pH and ionic strength triggered destabilization of biocompatible stable water-in-oil-in-water (W/O/W) emulsions
