Document Type

Dissertation - Open Access

Award Date

2022

Degree Name

Doctor of Philosophy (PhD)

Department / School

Dairy and Food Science

First Advisor

Lloyd Metzger

Keywords

Calcium reduced casein, Casein, casein functional properties, MCC, milk filtration, process cheese product

Abstract

Protein is an essential dietary component, and sufficient intake is vital in a healthy and balanced diet. Consumers are becoming increasingly aware of and knowledgeable about the role of protein in the diet. Two of the next-generation dairy protein ingredients isolated from milk are micellar casein (MCC) and milk-derived whey protein, isolated from skim milk using microfiltration (MF). Membrane filtration has been used extensively by the dairy industry to produce a variety of dairy ingredients from milk. MCC manufactured from freshly pasteurized milk can be directly consumed or as a supplement to fortify and enhance nutritional qualities in processed food products. However, the use of MCC as an ingredient in food applications is sometimes limited due to some of its poor functional properties. Therefore, several researchers studied different ways to improve the functionality of the MCC. One of them is the acidification of milk to solubilize colloidal calcium. The first objective of this study was to develop a novel filtration method to manufacture MCC with higher soluble casein factions while effectively removing the calcium from acidified skim milk. Although some of the previous studies achieved a 50% reduction in calcium, there might be a loss of soluble caseins through MF permeate when MF-DF is directly applied to acidified skim milk. In addition, acidification of milk with any acid salts is nonreversible, whereas acidification of milk with CO2 is reversible. Hence an alternate strategy for improving casein functional properties via shifts in protein and mineral distributions is manufacturing modified milk protein ingredients by acidifying the milk through CO2 injection, giving a clean label functional MCC. In this study, we have evaluated the novel process of producing calcium reduced micellar casein concentrate powders (RC-MCC) using MF, UF-DF, and injecting the CO2 into the liquid Micellar casein to lower the pH to 5.7 and maintain the same pH during the UF-DF process. This novel production process resulted in an RC-MCC with 30% less calcium than the C-MCC, retaining higher soluble casein fractions; otherwise, it would have permeated through the MF when only MF is used to produce MCC powders. Furthermore, the retention of serum casein in the resultant RC-MCCs was established quantitively by comparing the ζ-potential and particle size distribution values of RC-MCC and C-MCC powders. We conclude that an additional UF-DF and CO2 injection step to the current standard only MF process could produce reduced calcium MCCs without losing a lot of serum casein fractions generating because of pH adjustment to solubilize calcium. The objective of the second study was to evaluate the physicochemical and functional properties of 30% reduced calcium MCCs (RCMCC) produced in the first study to confirm improved functionality of RCMCC powders with higher soluble caseins lower calcium content. This study evaluated the pilot-scale production of calcium-reduced MCC 80 powders using a novel Microfiltration-CO2 injection-Ultrafiltration process and the effect of the calcium reduction on the physicochemical and functional properties of the RC-MCC powders and dispersions, respectively. In addition, control micellular casein powders (C-MCC) without CO2 injection were also compared with RC-MCC. This study confirmed significantly improved instant solubility and heat stability of the RC-MCC powders. In addition, reducing calcium was observed to improve foam capacity; however, the emulsions stability and foam stability were lower than control powder dispersions. This could be attributed to smaller particle size and not enough viscosity to retard the coalescence of smaller oil droplets or foam bubbles. The objective of the third study was to determine if a process cheese product (PCP) could be produced with less emulsifying salts if 30% reduced calcium RCMCC is utilized in the formulation and its impact on the functional properties of PCP. PCP formula made with reduced calcium MCC at 25% less emulsifying salt than control PCP had improved the functional characteristics. Using reduced calcium MCC, PCP manufactured with 25% less emulsifying salts showed a significant decrease in hardness, improved meltability, and optimal viscosity, confirming improved emulsification in the process cheese products. Consequently, this study concluded a 30% reduced calcium MCC powder could be used to partially replace emulsifying salt up to 25% in PCP manufacture.

Library of Congress Subject Headings

Process cheese.
Casein.
Micelles.
Milk proteins.

Number of Pages

157

Publisher

South Dakota State University

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Rights Statement

In Copyright