Coconut oil body membrane materials and storage proteins as emulsifiers : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Food Technology at Massey University, Manawatū, New Zealand. EMBARGOED until 7 July 2027.
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Date
2025
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Massey University
Embargoed until 7 July 2027
Figures are reproduced with permission
Embargoed until 7 July 2027
Figures are reproduced with permission
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© The Author
Abstract
As consumer preferences shift towards natural and sustainable food ingredients, plant emulsifiers are emerging as feasible alternatives to synthetic and animal-based options. This PhD thesis aimed to investigate the emulsifying potential of two coconut-derived components: oil body membrane materials (OBMMs) and press cake proteins. The study began with the extraction and characterisation of coconut oil bodies (OBs) from fresh and frozen coconuts (Chapter 4). The objective was to establish an extraction protocol that maximises the OB yield. The interactions between OB membranes and non-OB proteins were also examined through various washing techniques. Findings indicated that OB yield from frozen coconuts exhibited less variability than that from fresh coconuts and revealed considerable amounts of exogenous proteins within the OBM protein fraction. Next, the research focused on optimising the extraction and functionality of OBMMs obtained through churning or freeze–thawing (Chapter 5). The main goal was to identify OBMM composition and improve its emulsification properties via extraction method optimisation. Results showed that freeze–thawing proved more effective than churning for OBMM extraction yield, with an additional freeze–thawing step further improving the functionality of the resulting OBMMs. This project then investigated the extraction and fractionation of coconut oil press cake proteins with the goal of obtaining a fraction with emulsification properties (Chapter 6). Three protein fractions were produced for this purpose: those soluble at pH 7, soluble at pH 4.5, and insoluble at pH 4.5. Findings highlighted that variable costs, particularly raw material expenses, greatly impacted the production cost of pH 4.5 insoluble proteins. Finally, the emulsification properties of coconut press cake protein fractions (obtained in Chapter 6) were evaluated in oil-in-water emulsions (Chapter 7). Results show that pH 4.5 insoluble fraction exhibited the highest emulsification ability and emulsion stability. Additionally, the emulsions with excess proteins (> 1.5% w/w) showed a time-dependent flocculation, which was attributed the slow bridging interactions between adsorbed and unadsorbed proteins. Overall, this study characterises coconut-derived materials (OBMMs and press cake proteins) and determines their emulsifying capabilities to indicate their suitability for emulsion-based food systems. It also highlights that minimally purified plant materials can maintain functional properties, offering natural and sustainable emulsifier alternatives.
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Keywords
emulsification functionality, coconut protein, oil body, olesosome, Emulsions, Coconut oil, Plant organelles