Strategies for fortifying dairy protein-based formulated nutritional products with calcium

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Barone, Giovanni
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University College Cork
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The technological challenges associated with calcium (Ca) fortification of dairy-based nutritional products, such as poor heat stability, high viscosity, physical instability and impaired heat transfer, limit the addition of high levels of Ca. This thesis describes novel research into the development of strategies for fortifying liquid dairy protein-based formulated nutritional products with Ca. The interactions between dairy proteins, specifically whey protein concentrate ingredients enriched in alpha-lactalbumin (LAC) and Ca, in different physical forms (soluble and insoluble), were systematically investigated. Determining the inter-relationships between process composition and functionality of LAC ingredients was critically important in understanding the Ca-protein interactions of these ingredients in simple (e.g., single protein ingredient solutions) and complex dairy-based systems (e.g., model infant formulae). Macro-chemical composition differed significantly between LAC ingredients, specifically fat (0.40–9.32%) and carbohydrate content (0.31–13.1%), which impacted bulk handling and rehydration properties. The protein profile and proportion of denatured whey protein in the ingredients were also different, while the LAC ingredients all displayed higher proportions of essential amino acids, compared to whey protein ingredients with unmodified protein profile. Fortification of LAC solutions with soluble Ca showed similar or greater Ca-protein interactions compared to benchmarks, with the LAC ingredient manufactured using selective protein precipitation possessing strongest ability to bind Ca, with affinity constant values of 1.63 x 10-7. Reduction of mean particle size of insoluble Ca salts enhanced the colloidal stability of calcium-fortified LAC solutions and two commercial infant formulae compared to the use of Ca salts with larger mean particle size. The learnings obtained were applied in a model infant milk formula (IMF) fortified with different ratios of insoluble:soluble Ca salts. Varying the insoluble:soluble salt significantly impacted the physicochemical, rheological and thermal stability of the IMF. The extent of these changes were greater at pH 6.40 than 6.80 or 7.20, with aggregation of protein and/or protein-stabilised oil droplets being influenced by ionic Ca concentration. The findings presented in this thesis constitute a significant advancement to the body of knowledge on the interactions between dairy proteins and Ca, essential for the development of next-generation strategies for the fortification of dairy-based nutritional products with Ca.
Dairy , Whey protein , Nutritional products , Calcium-fortification , Alpha-lactalbumin , Mineral fortification , Calcium-protein interactions
Barone, G. 2019. Strategies for fortifying dairy protein-based formulated nutritional products with calcium. PhD Thesis, University College Cork.
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