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Title: Crystallisation and deposition behaviour of palm oil fractions
Author: Fitzgerald, A. M.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2003
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A model fat system to study the phenomenon of undesired deposition in food fat distribution lines was developed and characterised after consideration of the major triglyceride fractions that were found to be present in core analyses and in related systems exhibiting unwanted crystal formation in palm oil based products and fat blends. The model fat solution utilised was a blend of tripalmitin, the highest melting point triglyceride present in palm oil, and an inert paraffin solvent. A batch crystalliser was commissioned and techniques were developed and validated for sampling the crystallising solution and isolating crystal samples without the introduction of artefacts. Protocols and methods for analysis of crystal samples e.g. particle size distribution were developed and verified. Results from the batch crystallisation experiments indicated that there were two main modes of crystal formation which determined the type and nature of the crystals formed. A deposition flow cell apparatus was commissioned in which the mean flow velocity and coolant temperatures could be varied. A heat flux sensor was incorporated into the flow cell to allow in-situ monitoring of the extent of disposition. The apparatus was designed so that the deposit formed could be monitored visually during deposition and could be readily removed for closer examination of its microstructure. The data from the heat flux sensor in the flow cell was used to generate real-time deposit thickness profiles and fouling rates. Results from the deposition experiments indicated that there are two main modes of deposition. The first occurs at low saturation levels and at a small temperature driving force, where the deposit grows slowly and steadily to reach an asymptote with no evidence of removal, therefore indicating that the deposit is relatively strong in nature. The second type of deposition observed involved rapid growth with frequent removal (sawtooth behaviour) indicating a weaker deposit. This latter type of behaviour was seen predominantly at high concentrations and with large temperature differentials.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available