Native milk fat globules and buttermilk powder : novel emulsifiers for making ice cream : a thesis presented in partial fulfilment of the requirements for the degree of Master of Food Technology at Massey University, Manawatū, New Zealand
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Date
2021
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Massey University
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Abstract
Monoglycerides have been used in ice cream formulations for over seven decades. Monoglyceride addition is known to promote the dual mechanisms of (i) fat agglomeration and (ii) the adsorption of fat droplets to bubble surfaces during freezing which in turn improves the melt stability and sensory attributes of ice cream. The synthetic nature of commercial emulsifiers, coupled with trends in clean label manufacture, provides the motivation for exploring formulation/processing pathways that can generate equivalent product structures without these additives. This thesis represents a research study to replicate the whipping functionality of non-homogenized cream in an ice cream formulation and the use of milk phospholipids as an alternative to monoglycerides in ice cream production. In the first part of the study, ice cream mixes were prepared with the partial replacement of homogenized anhydrous milk fat with different % of non – homogenized cream. The resultant ice creams were analysed for microstructure, melt stability, material properties, and size distribution of melted ice cream to measure the extent of fat agglomeration. The differences in degree of fat destabilization, structural and material properties indicated that the replacement of homogenized fat with non-homogenized cream resulted in a positive effect on melt stability and a softer texture. Overall, findings suggest that replacing 40% of total fat in ice cream with native milk fat globules provides optimum results and can potentially be used as an alternative to monoglycerides. In the second part of the study, ice creams were prepared using a phospholipid enriched buttermilk powder (BMP @ 1-4%) as part of a conventional formulation (~35% total solids). Mix processing was adapted to allow the BMP to be either the sole emulsifier during homogenization, or a part of the combined milk solids fraction. Melt stability and material properties of the ice creams were evaluated, along with confocal and cryo-scanning electron microscopy analysis, and particle sizing of ice cream melts to determine the extent of fat agglomeration. All ice creams containing BMP were seen to have a positive effect on melt stability. Measured differences in the extent of fat agglomeration, ice cream structural and material properties indicated that structural assembly during freezing varied according to both BMP content and mix processing pathway. Overall, findings suggest that milk phospholipids can be used to replicate functional aspects of monoglyceride properties in ice cream.
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All copyrighted Figures and Table 2.2 are re-used with the publishers' permission.