Amsha Nahid

Doctor of Philosophy, (Bioprocess Engineering)
Study Completed: 2008
College of Sciences


Thesis Title
Modeling Heat Transfer in Butter Products

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Ms Nahid focused on mathematically modelling the freezing and thawing behaviour of butter products in different industrial scenarios. Research showed that water in butter supercools many degrees below its initial freezing point before freezing, due to its water in oil emulsion structure. During freezing, the release of latent heat was observed as a temperature rebound, which is controlled as much by the rate of crystallisation of water in each droplet as by the rate of heat transfer. This phenomenon was modelled successfully by considering heat conduction combined with a crystallisation kinetic model. Models for individual blocks were then extended to predict heat transfer in butter pallets for different industrial scenarios. The models have been used by the project sponsor (Fonterra) to help assess the impact of production and distribution practises on butter quality.

Professor John Bronlund
Professor Don Cleland