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Effects of Partial Calcium Depletion on the Reconstitution Behavior and Functional Properties of Milk Protein Concentrate Powder

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Title: Effects of Partial Calcium Depletion on the Reconstitution Behavior and Functional Properties of Milk Protein Concentrate Powder
Author: Eshpari, Hadi
Department: Department of Food Science
Program: Food Science
Advisor: Corredig, Milena
Abstract: In response to the increasing demand for high quality proteins in today’s diet, milk protein concentrate powders (MPC) have been increasingly utilized in different food applications, as a shelf stable source of highly nutritional and functional milk proteins in food. Understanding the factors affecting both rehydration and functional properties of these powders is critical to their optimal utilization. The objective of this thesis was to obtain a better understanding of the influence of partial acidification of milk prior to ultrafiltration on the rehydration properties of the casein micelles as well as on some of their processing functionality, namely, their rennet induced gelation and thermal stability. The MPC samples were prepared either by ultrafiltration (65% protein, MPC65) or by ultrafiltration followed by diafiltration (to reach 80% protein, MPC80), using pasteurized skim milk, at either the native milk pH (~pH 6.6) or at pH 6.0 after addition of glucono-δ-lactone, followed by spray drying. Acidification of milk to pH 6 increased the solubility of the resulting MPC powders compared to the control MPC samples. Acidification also caused solubilization of colloidal calcium phosphate and micellar dissociation, as indicated by a dramatic increase in the concentration of soluble casein. The increased level of soluble caseins showed a detrimental effect on the chymosin-induced gelation properties of the reconstituted MPC powders. The release of caseinomacropeptide across different treatments was not significantly different but the secondary stage of the gelation was negatively affected by the presence of soluble caseins. Reconstituted MPC powders made with partially acidified milk exhibited very poor thermal stability compared to MPC powders made with milk at its natural pH. The thermal stability of the acidified MPC dispersions was not only recovered by restoration of pH and the serum composition through dialysis against milk, but it was improved compared to control MPC dispersions. This research contributed to a better understanding of the functionality of casein micelles in MPC powders after rehydration, as affected by pH modification of milk prior to membrane filtration with an emphasis on the roles of mineral equilibrium, casein micelles and their modifications through both manufacturing and rehydration conditions.
Date: 2016-01
Rights: Attribution-NonCommercial-NoDerivs 2.5 Canada
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Attribution-NonCommercial-NoDerivs 2.5 Canada Except where otherwise noted, this item's license is described as Attribution-NonCommercial-NoDerivs 2.5 Canada