Use of a Poisson-Gamma regression model to assess the process hygiene criterion for Enterobacteriaceae on Irish sheep carcasses (original) (raw)
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2011
In modelling risk management strategies (i.e., with in-lot batch testing, statistical process control), two basic assumptions have been normally made: that the true concentration of microorganisms are log-normally distributed within a batch, and that the variance of the samples is the same for a little or highly contaminated lot. These assumptions were evaluated by characterisin g the between-batch and within-batch variability in microbial counts within a heterogeneous Poisson the oretical interpretation; this is a gamma or a logno rmal true or population distribution for the unknown microbial concentration and a Pois s n measurement distribution that produces a discrete Poisson-gamma or a Poisson -lognormal distribution of observed plate counts. Two variants of random-effects regressions based o n the Poisson-gamma (m,1/k) and the Poissonlognormal (μ,σ) models were fitted to two microbial data sets of TVC (high counts) and Escherichia coli (low counts) on pre-chill beef carcasses s...
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Quantity-based microbiological sampling plans and quality after inspection
Sampling inspection plans are principally used to determine whether a batch of food is contaminated or not. In this theoretical research, we study the effect of increasing the analytical unit amount on the performance of microbiological sampling plans, and on the resulting quality after inspection. We discuss several scenarios of homogeneous and inhomogeneous contamination for assessing the consumer's risk. Several statistical approaches to describe the effect of an increase in analytical amount are studied. We provided a procedure for designing of the sampling plan for a given consumer's risk and according to different dispersion parameters and contamination levels.
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Investigation on Lamb Meat Production Hygiene in Facilities with Low and High Production Capacity
Bulgarian Journal of Veterinary Medicine, 2010
Summary Feizullah, F. & H. Daskalov, 2010. Investigation on lamb meat production hygiene in facilities with low and high production capacity. Bulg. J. Vet. Med. , 13, No 4, 252 −258. A comparative study on the microbiological parameters related to the hygiene status of two lamb slaughtering and processing facilities with low and high production capacity was performed. The data showed that the total viable count of microorganisms (TVC) varied between 4.09 and 6.79 log 10 cfu/cm 2 on small ruminant carcasses (SR) slaughtered at the smaller facility, while in the larger factory, the values varied between 4.32 and 7.20 log 10 cfu/cm 2 . The values for Enterobacteriaceae varied within 1.30 to 3.18 log 10 CFU/cm 2 for the smaller factory and 1.27 to 6.05 log 10 cfu /cm 2 for the high capacity slaughterhouse. The results about the presence of E. coli were within the boundaries of 1 to 1.65 log 10 cfu /cm 2 for the small factory and 1.62 to 2.01 log 10 cfu /cm 2 for the facility with high c...
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