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Amornrat Anprasertporn ID 3042343 (Ph.D. Thesis)

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Amornrat Anprasertporn ID 3042343 (Ph.D. Thesis) MICROBIOLOGICAL ANALYSES OF EGGS AND EGG PRODUCTS USING THE MICROFOSS SYSTEM by Amornrat Anprasertporn M Sc. Food Science and Technology (University of Western Sydney, Hawkesbury, Australia) A thesis submitted for the degree of Doctor of Philosophy in Food Science and Technology School of Chemical Sciences and Engineering The University of New South Wales 2009 PLEASE TYPE THE UNIVERSITY OF NEW SOUTH WALES Thesis/Dissertation Sheet Surname or Family name: ANPRASERTPORN First name: AMORNRAT Other name/s: Abbreviation for degree as given in the University calendar: PhD School: School of Chemical Science and Engineering Faculty: Faculty of Engineering Title: Microbiological analyses of eggs and egg products using the MicroFoss system Abstract 350 words maximum: (PLEASE TYPE) This thesis evaluates the MicroFoss system, also known as the BioSys or the Soleris® system, as a rapid method for microbiological analyses of eggs and egg products. Commercially assays for assessment of microbiological quality and sanitation conditions during processing, which are total viable counts (TVC), coliforms and Escherichia coli, are evaluated in comparison to the cultural methods. Concurrently, this thesis reports development of a new medium for the MicroFoss Salmonella detection, since this test is not available. Good correlations between the cultural TVCs and the MicroFoss detection times (DTs) were obtained (r ≥-0.84) in all egg products. Preliminary results of a correlation between the cultural TVCs dominated by Pseudomonas fluorescens and the MicroFoss DTs suggested that the MicroFoss could be used for investigation of spoilage and shelf life prediction of eggs. High agreements (r ≥-0.93) between the MicroFoss and cultural methods for coliforms and E. coli in eggs and egg products was achieved as well as the accuracy, sensitivity and specificity. The MicroFoss for estimations of TVC, coliforms and E. coli could be completed in less than 24h, compared to 48-72h required for the cultural methods. Hence, the MicroFoss could be used as a rapid screening for quality control of eggs and egg products. While a new propylene glycol-based selective medium developed was effective for detection of Salmonella, possible false positive results caused by certain bacteria, such as Enterobacter cloacae, E. coli, Klebsiella pneumoniae and Proteus mirabilis, were encountered. When this selective medium was supplemented with 40 mg/L of novobiocin, or 1 or 2 mL/L of Niaproof 4, these non-salmonellae were greatly suppressed or eliminated, particularly Pr. mirabilis, whilst this did not affect growth of Salmonella. Various serotypes of Salmonella including strains of atypical biotype were able to acidify propylene glycol in these media. Detection of Salmonella in naturally contaminated eggs by the MicroFoss using propylene glycol-based selective media showed equivalent sensitivity and specificity to the Australian Standard 5013.10-2004, according to numbers of egg samples tested in this study. Detection of low level of Salmonella (1-10 CFU/25g of eggs pre-enriched in buffered peptone water) was achieved in less than 24h. Declaration relating to disposition of project thesis/dissertation I hereby grant to the University of New South Wales or its agents the right to archive and to make available my thesis or dissertation in whole or in part in the University libraries in all forms of media, now or here after known, subject to the provisions of the Copyright Act 1968. I retain all property rights, such as patent rights. I also retain the right to use in future works (such as articles or books) all or part of this thesis or dissertation. I also authorise University Microfilms to use the 350 word abstract of my thesis in Dissertation Abstracts International (this is applicable to doctoral theses only). …………………………………………………………… ……………………………………..……………… ……….……………………...…….… Signature Witness Date The University recognises that there may be exceptional circumstances requiring restrictions on copying or conditions on use. Requests for restriction for a period of up to 2 years must be made in writing. Requests for a longer period of restriction may be considered in exceptional circumstances and require the approval of the Dean of Graduate Research. FOR OFFICE USE ONLY Date of completion of requirements for Award: THIS SHEET IS TO BE GLUED TO THE INSIDE FRONT COVER OF THE THESIS ORIGINALITY STATEMENT ‘I hereby declare that this submission is my own work and to the best of my knowledge it contains no materials previously published or written by another person, or substantial proportions of material which have been accepted for the award of any other degree or diploma at UNSW or any other educational institution, except where due acknowledgement is made in the thesis. Any contribution made to the research by others, with whom I have worked at UNSW or elsewhere, is explicitly acknowledged in the thesis. I also declare that the intellectual content of this thesis is the product of my own work, except to the extent that assistance from others in the project's design and conception or in style, presentation and linguistic expression is acknowledged.’ Signed …………………………………………….............. Date ……………………………………………............…. COPYRIGHT STATEMENT ‘I hereby grant the University of New South Wales or its agents the right to archive and to make available my thesis or dissertation in whole or part in the University libraries in all forms of media, now or here after known, subject to the provisions of the Copyright Act 1968. I retain all proprietary rights, such as patent rights. I also retain the right to use in future works (such as articles or books) all or part of this thesis or dissertation. I also authorise University Microfilms to use the 350 word abstract of my thesis in Dissertation Abstract International (this is applicable to doctoral theses only). I have either used no substantial portions of copyright material in my thesis or I have obtained permission to use copyright material; where permission has not been granted I have applied/will apply for a partial restriction of the digital copy of my thesis or dissertation.' Signed ……………………………………………........................... Date …………………………………………….........................…. AUTHENTICITY STATEMENT ‘I certify that the Library deposit digital copy is a direct equivalent of the final officially approved version of my thesis. No emendation of content has occurred and if there are any minor variations in formatting, they are the result of the conversion to digital format.’ Signed ……………………………………………........................... Date …………………………………………….........................…. i ACKNOWLEDGEMENTS I would like to extend my sincere thanks firstly to my supervisor, A/Prof. Julian Cox. The guidance shown during the course of my study has been essential in achieving the results shown in this thesis. Prof. Graham Fleet’s input has been invaluable over the last 9 months; helping steer and motivate me over the final stages of this work and for that I thank you. This project could not have proceeded without the valuable material support provided by Foss Pacific. I also would like to thank the commercial egg supplier for providing products for testing. For all the time spent looking after the laboratories, making sure everything ran smoothly I must thank Camillo Taraborrelli. The statistical help provided by Prof. William Dunsmuir is also greatly appreciated. All those long days and nights spent in the laboratory could not have allowed me to keep my sanity without the fun and supportive environment provided by all the students, especially Peter, Lidia, Hugh, Jum, Ai Lin, Sungsook and Maria. The friendship’s made during this time have been truly wonderful. Lastly, thanks must be given to my wonderful parents, family, and friends for their kind support, and caring attitude; Sonia for reading, and my Samee for looking after me. ii LISTS OF PRESENTATION AND PAPERS Cox, J.M. and Anprasertporn, A., 2003. Estimation of coliforms in eggs and egg products by the MicroFoss system. 11th Australian Food Microbiology Conference, AIFST, 26th – 28th March 2003, Noosa. The calibration curves were utilised by a commercial egg manufacturer. Results from ongoing testing of egg products by this commercial egg manufacturer corresponded well with those from this research. This confirmed the validity of the findings from this study. Possible commercialisation of the medium for Salmonella detection developed in this research. Interest shown by a third party and New South Innovations. iii TABLE OF CONTENTS ORIGINALITY STATEMENT, COPY STATEMENT, AND i AUTHENTICITY STATEMENT………………………………………………. ACKNOWLEDGEMENTS……………………………………………………... ii LISTS OF PRESENTATIONS AND PAPERS………………………………… iii TABLE OF CONTENTS……………………………………………………….. iv ABSTRACT…………………………………………………………………….. 1 CHAPTER 1: INTRODUCTION……………………………………………….. 3 CHAPTER 2: LITERATURE REVIEW………………………………………... 8 2.1 Introduction…………………………………………………………… 8 2.2 Eggs and egg products………………………………………………… 9 2.3 Microbiology of eggs and egg products………………………………. 9 2.3.1 Shell eggs………………………………………………………… 10 2.3.2 Pasteurized egg products………………………………………… 15 2.3.3 Dried egg products………………………………………………. 18 2.4 Structural properties of eggs to microbial resistance…………………. 20 2.4.1 Cuticle……………………………………………………………. 21 2.4.2 The true shell…………………………………………………….. 22 2.4.3 Shell membranes…………………………………………………. 23 2.4.4 Albumen…………………………………………………………. 24 2.4.5 Chalaziferous layer………………………………………………. 25 2.4.6 Vitelline membrane……………………………………………… 26 2.4.7 Yolk………………………………………………………………
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