Solubility and structure of milk powders manufactured with the addition of disodium phosphate and tetrasodium pyrophosphate mixtures

ABSTRACT

This study aimed to investigate the effect of adding binary mixtures of disodium phosphate and tetrasodium pyrophosphate during milk powder production. Overall, the addition of disodium phosphate–tetrasodium pyrophosphate caused an increase in pH and a decrease in the acidity and turbidity of reconstituted milk samples. The decrease in turbidity was attributed to either dispersion or swelling of the casein micelles. The addition of mixtures containing the lowest amounts of tetrasodium pyrophosphate considerably reduced the insolubility index, whereas mixtures containing higher levels of tetrasodium pyrophosphate exerted a detrimental effect on solubility. Interestingly, microscopic observations showed large agglomerated particles in mixtures with the highest level of tetrasodium pyrophosphate. We hypothesized that the formation of casein calcium–pyrophosphate complexes led to the higher insolubility index in this mixture.

KEYWORDS:

• milk powder
• scanninng electron microscopy (SEM)
• emulsifying salts
• solubility
• turbidity
• acidity

Acknowledgments

The authors thank the Department of Food Science and Technology and the National Nutrition and Food Technology Research Institute (Shahid Beheshti University of Medical Sciences) for providing the spray dryer facility and scientific and technical assistance in milk powder production.