Modelling dairy biofilms for targeted control of thermophilic bacteria

Li, Isabel Huizi

Modelling dairy biofilms for targeted control of thermophilic bacteria

aut.embargo	No	en_NZ
aut.embargo.suppdate	2015-10-23
aut.embargo.supplementary	Yes
aut.supplementaryupload	Yes
aut.thirdpc.contains	No	en_NZ
aut.thirdpc.permission	No	en_NZ
aut.thirdpc.removed	No	en_NZ
dc.contributor.advisor	Brooks, John
dc.contributor.advisor	Flint, Steve
dc.contributor.advisor	Linsay, Denise
dc.contributor.author	Li, Isabel Huizi
dc.date.accessioned	2014-11-27T02:07:26Z
dc.date.available	2016-05-24T00:02:52Z
dc.date.copyright	2013
dc.date.created	2014
dc.date.issued	2013
dc.date.updated	2014-11-26T21:20:38Z
dc.description.abstract	Biofilms are the main source of bacterial contamination in dairy manufacturing plants. Strategies to mitigate biofilm development in dairy manufacture aim to improve the microbiological quality of the products manufactured and to maximize the run length of manufacturing plants, and thereby obtain substantial economic benefits. A simple strategy involves creating an unstable environment for microbial growth by manipulating conditions, such as temperature, on a sufficiently frequent basis to disrupt biofilm growth while maintaining the ability to manufacture high quality products. Thermophilic bacilli, Geobacillus stearothermophilus and Anoxybacillus flavithermus, are the main contaminants responsible for economic loss in milk powder production all over the world, colonising plant and persisting through cleaning. Because of the significant economic loss caused by thermophilic biofilms, there is an urgent need to study these bacteria. In my research I investigated the hypothesis that a mathematical model can represent the growth of these thermophilic bacteria as biofilms in milk powder plants and whether the model can be used to optimise methods to control these bacteria. A novel technology, called temperature cycling, was studied in depth in this research, involving creating an unstable environment for microbial growth by manipulating the temperature, on a sufficiently frequent basis to disrupt biofilm growth, while limiting the amount of dangerous chemicals used for cleaning and maintaining the ability to manufacture dairy products hygienically. Robust and practical models were designed based on the logistic growth equation for a laboratory scale milk heating plant. The models can be run without recourse to extensive computing power and can be used in the dairy industry as decision making tools, which can provide instantaneous prediction of the thermophile level of the product for a known level of incoming thermophilic bacteria.	en_NZ
dc.identifier.uri	https://hdl.handle.net/10292/7993
dc.language.iso	en	en_NZ
dc.publisher	Auckland University of Technology
dc.rights.accessrights	OpenAccess
dc.subject	Modelling	en_NZ
dc.subject	Biofilm	en_NZ
dc.subject	Anoxybacillus	en_NZ
dc.subject	Geobacillus	en_NZ
dc.subject	Temperature cycling	en_NZ
dc.title	Modelling dairy biofilms for targeted control of thermophilic bacteria	en_NZ
dc.type	Thesis
thesis.degree.discipline
thesis.degree.grantor	Auckland University of Technology
thesis.degree.level	Doctoral Theses
thesis.degree.name	Doctor of Philosophy	en_NZ