Mechanical integrity and rehydration properties of agglomerated nutritional dairy ingredient powders

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Hazlett, Ryan
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University College Cork
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The functional properties of nutritional dairy powders are key in determining the ease at which they can be stored, handled and further applied in formulations or on direct consumer application. Powder agglomeration is a unit operation employed during the spray drying process, in order to obtain a greater control of the resulting powder’s physical, bulk handling and functional properties. The studies presented in this thesis explore the importance of maintaining agglomerate integrity on powder handling (i.e., powder conveying) post-spray drying, while presenting novel research findings in the application of agglomeration for the modification of commercially important, high-protein content dairy powders (e.g., milk protein isolate; MPI). Initially, a custom fabricated pressure dispersion rig was utilised to achieve breakdown of agglomerated powder particles, similar to that occurring in industrial powder conveying systems (i.e., lean phase conveying). Analysis of the resulting powders showed that the significant alterations in both powder physical and bulk properties (i.e., decreased particle size, increased bulk density and increased surface free fat concentrations), occurring on agglomerate breakdown, significantly impaired the functionality (i.e., flowability and rehydration) of a range of commercially agglomerated nutritional dairy powders (i.e., whey protein concentrate, fat-filled milk powder and an infant formula powder). In addition, the agglomeration of MPI was researched, focusing on the utilisation of novel protein-based binders to achieve agglomeration. The results demonstrated that the use of novel protein-based binder solutions achieved a greater extent of agglomeration in comparison to more traditional binder solutions (i.e., water or lactose), ultimately improving the flowability and wetting properties of MPI powders. The conclusions of this thesis demonstrate the importance of maintaining the mechanical integrity of agglomerated dairy powders and the potential for the further application of agglomeration using novel protein-based binder solutions to tailor the functionality of high-protein dairy powders, such as MPI.
Dairy powders , Rehydration properties , Powder agglomeration , Agglomerate breakdown , Powder flowability
Hazlett, R. 2019. Mechanical integrity and rehydration properties of agglomerated nutritional dairy ingredient powders. MRes Thesis, University College Cork.