Biography:

In the past T.A. McMeekin has collaborated on articles with C.J. Thomas and T. Ross. One of their most recent publications is ReviewApplication of predictive microbiology to assure the quality and safety of fish and fish products. Which was published in journal International Journal of Food Microbiology.

More information about T.A. McMeekin research including statistics on their citations can be found on their Copernicus Academic profile page.

T.A. McMeekin's Articles: (9)

ReviewApplication of predictive microbiology to assure the quality and safety of fish and fish products

AbstractPredictive microbiology offers an alternative to traditional microbiological assessment of food quality and safety. The concept is that a detailed knowledge of the microbial ecology of a food product can be expressed as a mathematical model to enable objective evaluation of the effect of processing, storage and distribution operations on microbial development.Experience to date indicates the need initially to derive a mathamatical model in laboratory studies, to validate the model in food products and to incorporate the information into monitoring devices. These may be chemical or physical indicators or electronic integrators or laggers. To enable a correct decision on quality or safety, it is essential that the response of the monitoring device to environmental changes mimics exactly that of the organism of concern.Most monitoring devices currently available record temperature history, but not other environmental factors that influence growth and that, in some circumstances, change during storage. The next generation of monitoring devices may be required to monitor several parameters to take full advantage of increasingly accurate and sophisticated models.

Bacterial penetration of chicken breast muscle

AbstractPure cultures of motile, but not non-motile strains of bacteria penetrated blocks of chicken breast muscle, irrespective of ability to hydrolyse gelatin, casein or soluble meat proteins. Penetration occurred as a result of movement of bacteria between the endomysial sheath and associated muscle fibres. Rates of penetration recorded were temperature dependant, affected by tissue moisture content and favoured by proteolytic activity, but were independent of growth rate. In addition, mixtures of proteolytic and non-proteolytic cultures enhanced the penetration rate of the non-proteolytic strains. Other experiments using mixed inocula, indicated some strains of non-motile, non-invasive bacteria may be carried into muscle by motile, invasive strains.

4 - Risk assessment and pathogen management

Abstract:The commercial preparation of safe foods is widely considered to be best managed by ‘pre-requisite programs’ in combination with the Hazard Analysis Critical Control Point (HACCP) strategy. Formal risk assessment approaches have latterly been promoted and developed by national governments and international organisations for the purposes of establishing objective and fair rules for international trade in foods and for setting food safety management priorities and consequent regulatory actions. These initiatives are likely to affect the management of microbial food safety in industry. This chapter briefly describes the principles of and approaches to microbial risk assessment (MRA). The terminology of MRA, and its origins, are described and its application to managing the risk of foodborne pathogens and their toxins, including its integration with HACCP, are considered. It is suggested that the application of the tools and techniques of MRA in the food industry can assist in elucidating optimal food safety control options, identifying CCPs and specifying their limits and appropriate corrective actions. Thus, rather than replacing HACCP, MRA will help to optimise the HACCP systems of the food industry and individual food businesses to improve product safety and overall public health. Additionally, MRA can facilitate innovation in the food industry because it provides an agreed method for demonstration of the food safety equivalence of alternative processing technologies and formulations. Currently MRA is a high-level, resource- and time-intensive activity. Increasingly, the approaches of MRA are being applied to narrower food safety decisions, involving the development of ‘fit-for-purpose’ approaches to MRA. Examples are presented of the use of MRA approaches to support decision making by food businesses.

Modelling the effects of temperature, water activity, pH and lactic acid concentration on the growth rate of Escherichia coli

AbstractAn extended square root-type model describing Escherichia coli growth rate was developed as a function of temperature (7.63–47.43 °C), water activity (0.951–0.999, adjusted with NaCl), pH (4.02–8.28) and lactic acid concentration (0–500 mM).The new model, based on 236 growth rate data, combines and extends previously published square root-type models and incorporates terms for upper and lower limiting temperatures, upper and lower limiting pH, minimum inhibitory concentrations of dissociated and undissociated lactic acid and lower limiting water activity. A term to describe upper limiting water activity was developed but could not be fitted to the E. coli data set because of the difficulty of generating data in the super-optimal water activity range (i.e. >0.998). All data used to generate the model are presented.The model provides an excellent description of the experimental data.

Predictive microbiology: Quantitative science delivering quantifiable benefits to the meat industry and other food industries

AbstractPredictive microbiology is considered in the context of the conference theme “chance, innovation and challenge”, together with the impact of quantitative approaches on food microbiology, generally. The contents of four prominent texts on predictive microbiology are analysed and the major contributions of two meat microbiologists, Drs. T.A. Roberts and C.O. Gill, to the early development of predictive microbiology are highlighted. These provide a segue into R&D trends in predictive microbiology, including the Refrigeration Index, an example of science-based, outcome-focussed food safety regulation.Rapid advances in technologies and systems for application of predictive models are indicated and measures to judge the impact of predictive microbiology are suggested in terms of research outputs and outcomes. The penultimate section considers the future of predictive microbiology and advances that will become possible when data on population responses are combined with data derived from physiological and molecular studies in a systems biology approach.Whilst the emphasis is on science and technology for food safety management, it is suggested that decreases in foodborne illness will also arise from minimising human error by changing the food safety culture.

Halomonas meridiana, a New Species of Extremely Halotolerant Bacteria Isolated from Antarctic Saline Lakes

SummaryHalomonas meridiana sp. nov., is proposed for seven strains of halotolerant, non-pigmented bacteria isolated from several hypersaline lakes of the Vestfold Hills, Antarctica. These strains, plus 17 new isolates of the Antaractic species Halomonas subglaciescola and six reference strains of halotolerant bacteria, were tested for 134 physical and biochemical attributes. The data were analysed by numerical taxonomic procedures. The new isolates clustered most closely with the reference strains Halomonas elongata (ATCC 33173T) and Halomonas halmophila (NCMB 1971T) and furthest from Halomonas subglaciescola (UQM 2926T and UQM 2927), but were sufficiently distinct to be considered as a new species. The strains of Halomonas meridiana separated into two phenons but representatives of both groups had DNA with 59±1 mol% G+C.

Flectobacillus glomeratus sp. nov., a Curved, Nonmotile, Pigmented Bacterium Isolated from Antarctic Marine Environments

SummaryA new species of the genus Flectobacillus, Flectobacillus glomeratus, is described from antarctic marine environments. Strain ACAM 171 was isolated from Burton Lake (68°37.5′S;78°05′E). Another strain, ACAM 111, was isolated from surface seawater collected near Davis Base (68°34.6′S;77°58′E), in Prydz Bay. Cells of the strains are vibrioid to highly coiled. Cells of similiar morphology were located in these envirionments by fluorescence microscopy.The cells are Gram-negative, nonmotile and become coccoid in old or ageing cultures. The strains do not produce acids from carbohydrates or alcohols and do not grow on organic acids or alcohols as sole sources of carbon. They are obligate aerobes and require seawater or marine salts for good growth. ACAM 171 is psychrophilic and ACAM 111 is psychrotrophic. The strains contain pigments, either yellow or tan, which are not flexirubins. The G+C content of their DNA is 33.0 and 33.2 mol%. The type strain is UQM 3055 (ACAM 171).

Reuglar ArticleEffects of parameterization on the performance of empirical models used in `predictive microbiology'

AbstractEmpirical models fitted to measured data should be used only in the region within which measurements were made, the so-called interpolation region. In cases in which many variables are involved, the determination of the interpolation region is not self-evident and the region is sometimes unexpectedly small. A definition of the interpolation region is presented, to enable some consequences of the use of models with high numbers of parameters to be exemplified. In particular, unreliability close to the boundary of the interpolation region is highlighted by comparison of the predictions of models with different numbers of parameters.

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