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Microbial encapsulation and interactions in emulsions

El Kadri, Hani (2018)
Ph.D. thesis, University of Birmingham.

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Previous studies indicated that emulsions with nano-sized droplets or nano-emulsions possess anti-microbial activity. The microstructure of water-in-oil-in-water (W1/O/W2) emulsions present interest for microbial encapsulation in food, cosmetic and pharmaceutical applications. Therefore microbe-emulsion interactions need to be characterised in order to fully explore the potential of such applications. This thesis investigated the effect of nano-emulsions on bacteria as well as W1/O/W2 emulsion feasibility for encapsulation and triggered release (altering osmotic pressure) of bacteria and in real life application by incorporating in set-style yogurt model system for protection of probiotics were investigated.
Exposure of bacterial cells to nano-emulsions was found to have no significant effect on the survival or growth bacteria and cell membrane integrity was not compromised. Bacteria had no effect on the stability of nano- and double emulsions. The release of bacteria form W1/O/W2 emulsion occurred due to the bursting of the oil globules independent of diffusion mechanisms and be controlled by altering the structure of W1/O/W2 emulsion. W1/O/W2 emulsion had a significant effect on texture and physicochemical properties of yogurt but no effect on bacterial growth kinetics while probiotics maintained high viability at the end of the fermentation.
In summary, this thesis demonstrates the feasibility and applicability of W1/O/W2 emulsion for the encapsulation of microbial cells for the purpose of their protection and triggered release. The results of this thesis can be used in the formulation of better probiotic products, segregation, protection, and release of microbial cells during fermentation as well as for in vivo delivery of fermentation.

Type of Work:Ph.D. thesis.
Supervisor(s):Gkatzionis, Konstantinos and Overton, Tim
School/Faculty:Colleges (2008 onwards) > College of Engineering & Physical Sciences
Department:Chemical Engineering
Subjects:TP Chemical technology
Institution:University of Birmingham
ID Code:8192
This unpublished thesis/dissertation is copyright of the author and/or third parties. The intellectual property rights of the author or third parties in respect of this work are as defined by The Copyright Designs and Patents Act 1988 or as modified by any successor legislation. Any use made of information contained in this thesis/dissertation must be in accordance with that legislation and must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the permission of the copyright holder.
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