Influence of calcium, magnesium, or potassium ions on the formation and stability of emulsions prepared using highly hydrolyzed whey proteins.
Oil-in-water emulsions (4 wt % soy oil) containing 4 wt % whey protein hydrolysate (WPH) (27% degree of hydrolysis) and different levels of calcium, magnesium, or potassium chloride were prepared in a two-stage homogenizer. Other emulsions containing 4 wt % WPH but including 0.35 wt % hydroxylated lecithin and different levels of the above minerals were similarly prepared. The formation and stability of these emulsions were determined by measuring oil droplet size distributions using laser light scattering and by confocal scanning laser microscopy and a gravity creaming test. Both lecithin-free and lecithin-containing emulsions showed no change in droplet size distributions with increasing concentration of potassium in the range 0-37.5 mM. In contrast, the diameter of emulsion droplets increased with increasing calcium or magnesium concentration >12.5 mM. Emulsions containing hydroxylated lecithin were more sensitive to the addition of calcium or magnesium than the lecithin-free emulsions. Storage of emulsions at 20 degrees C for 24 h further increased the diameter of droplets and resulted in extensive creaming in emulsions containing >25 mM calcium or magnesium. It appears that both flocculation and coalescence processes were involved in the destabilization of emulsions induced by the addition of divalent cations.
Ramkumar
C
C
Institute of Food, Nutrition and Human Health, Massey University, Palmerston North, New Zealand.
Singh
H
H
Munro
P A
PA
Singh
A M
AM
D002118:Calcium / Q000737:chemistry*; D006868:Hydrolysis; D008274:Magnesium / Q000737:chemistry*; D008894:Milk Proteins / Q000737:chemistry*; D010713:Phosphatidylcholines / Q000737:chemistry; D011188:Potassium / Q000737:chemistry*
D008894:Milk Proteins; D010713:Phosphatidylcholines; C024471:whey acidic proteins; D008274:Magnesium; D011188:Potassium; D002118:Calcium