Classification of beef carcasses from Portugal using animal characteristics and pH/temperature decline descriptors.

Previous research showed that meat of optimal tenderness is produced when rigor mortis temperature falls between 12 - 35 °C. This study aimed to classify beef carcasses quality according to the ideal window rule using pH/temperature decay descriptors and animal characteristics. Seventy-four Mirandesa breed and 52 Crossbreds, with an average age of 10.1 ±â€¯2.32 months, were slaughtered at one abattoir located in the Northeast of Portugal. Carcass temperature and pH, logged during 24 h post-mortem, were modelled by exponential decay equations that estimated temperature (kT) and pH (kpH) decay rates. Additionally, other pH/temperature descriptors were estimated from the fitted models. From linear models adjusted to each descriptor, it was found that hot carcass weight, age, breed, gender, age class, fat cover, conformation and transport and lairage time had influence (P < 0.05) on pH and temperature decay rates. Thus, combining the variables kT and kpH, and selected animal/carcass characteristics as linear predictors, a system to classify quality of carcasses was developed.

Relating physicochemical and microbiological safety indicators during processing of linguiça, a Portuguese traditional dry-fermented sausage.

Linguiça is a Portuguese traditional fermented sausage whose microbiological quality and safety can be highly variable. In order to elucidate risk factors and the particularities of the manufacturing technology that explain the between-batch variability in total viable counts (TVC), Enterobacteriaceae, Staphylococcus aureus and Listeria monocytogenes in the product; microbiological and physicochemical characterisation of linguiça at five stages of production (i.e., raw pork meat, mixed with ingredients, macerated, smoked and ripened) was carried out. A total of six production batches were surveyed from two factories; one utilised curing salts and polyphosphate in their formulation (Factory II). The delayed fermentation in the nitrite-formulated sausages was partly responsible for the increase (p<0.01) in Enterobacteriaceae, S. aureus and L. monocytogenes from raw meat (3.21logCFU/g, 1.30logCFU/g and 22.2CFU/g, respectively) to the end of maceration (4.14logCFU/g, 2.10logCFU/g and 140CFU/g, respectively) while the better acidification process in the nitrite-free sausages (Factory I) led to lower counts of S. aureus (2.64logCFU/g) and L. monocytogenes (10CFU/g) in the finished products. In Factory II, although L. monocytogenes entered the chain at the point of mixing, it became steadily inactivated during smoking and ripening (<50CFU/g), despite the initially-delayed fermentation. Nitrite had a strong effect on reducing Enterobacteriaceae throughout smoking (r=-0.73) and ripening (r=-0.59), while it failed to control the growth of S. aureus. The main hurdle preventing the development of S. aureus in linguiça is the pH, and other factors contributing to its control are: longer ripening days (p=0.019), low S. aureus in raw meat (p=0.098), properly-washed casings (p=0.094), and less contamination during mixing (p=0.199). In the case of L. monocytogenes, at least three hurdles hinder its development in linguiça: low aw (p=0.004), low pH (p=0.040) and nitrite (p=0.060), and other factors contributing to its control are: longer ripening (p=0.072) and maceration (p=0.106) periods, lower aw at the end of smoking (p=0.076) and properly-washed casings (p=0.099). Results have shown that there is a need to standardise the productive process of linguiça, to optimise the initial acidification process, and to reinforce proper programmes of quality control of ingredients and good hygiene practices, so as to minimise the introduction of Enterobacteriaceae and pathogens from external sources.

Tracking the Salmonella status of pigs and pork from lairage through the slaughter process in the Republic of Ireland.

Salmonella Typhimurium is the predominant serotype isolated from humans in Europe. Pork and pork products are recognized vehicles of Salmonella and are responsible for outbreaks of human salmonellosis. Pigs can become infected with Salmonella on the breeding or fattening farm and during transport, lairage, and slaughter. The aim of this study was to investigate selected points of Salmonella contamination from the time pigs entered the lairage to the time the carcass was processed in the boning hall and to determine the importance of different sources of Salmonella along the Irish pork production chain. A second objective was to evaluate whether the serological status or category of a herd influenced the levels of bacteriological contamination detected on individual carcasses and pork cuts during slaughter and dressing operations. All samples were tested for the presence and numbers of Salmonella. Enterobacteriaceae numbers were also determined. Serotype, phage type, and pulsed-field gel electrophoresis were utilized to determine similarity among Salmonella isolates. Lairage was a major source of cross-contamination with Salmonella as were the hands of evisceration operatives, conveyor belts, and equipment in the boning hall. Cross-contamination within the slaughter plant environment accounted for up to 69 % of Salmonella carcass contamination. In general, herd category reflected the bacteriological status of carcasses and pork cuts. Major findings were a strong association (P < 0.01) between Enterobacteriaceae counts and Salmonella occurrence on prechill carcasses and a significant association (P < 0.05) between Enterobacteriaceae counts and Salmonella occurrence on pork cut samples.

Prevalence, numbers and characteristics of Salmonella spp. on Irish retail pork.

Salmonella is a common contaminant of raw pork and represents a public health risk. Both qualitative and quantitative data on Salmonella in pork at retail are required for assessment of consumer exposure to the pathogen. Pork samples (n=500) were collected at random from butchers' shops and supermarkets in the Republic of Ireland between January and November, 2007 and examined for prevalence and numbers of Salmonella using a PCR screen followed by cultural examination of positive samples. Salmonella numbers were assessed using a three tube most probable number (MPN) technique. Any Salmonella recovered were characterised by serotype, phage type and antibiogram, and subtyped by pulsed-field gel electrophoresis (PFGE). Enterobacteriaceae were also enumerated to see if there was a correlation between the Salmonella status of the pork and hygiene levels at retail outlets. Salmonella spp. were detected on 13/500 (2.6%) pork cuts at numbers between <0.03 and 2.10 MPN/g. The mean Enterobacteriaceae counts was 3.12 log(10) CFU/g (range -0.26-6.52 log(10) CFU/g). Salmonella Typhimurium was the most common serotype and the majority of isolates were multi antibiotic resistant. PFGE analysis showed evidence of persistence of some strains, with an S. Typhimurium U310 recovered from a pork abattoir being identical (100%) to a strain found a year later in a sample from a retail outlet. There was also evidence of cross contamination of Salmonella isolates between samples. There was a direct association between Salmonella contamination of pork and Enterobacteriaceae numbers, which indicates the need for good hygiene practices at retail for control of this pathogen.

A meta-analysis study of the effect of chilling on prevalence of Salmonella on pig carcasses.

In the field of food safety, meta-analysis can be used to combine results of prevalence studies of pathogens at critical stages within the food processing chain so that policy makers can access reliable and concise information on the effectiveness of interventions for controlling and preventing foodborne illnesses in humans. The objective of this work was to demonstrate the applicability of a parametric approach of meta-analysis to the specific case of determining the overall effect of chilling on Salmonella prevalence on pig carcasses. A meta-analysis was performed on each of two parameters measuring effect size for binary outcomes (relative risk and risk difference). Both meta-analyses confirmed that the chilling operation has a significant beneficial effect (P < 0.001) on the reduction of Salmonella prevalence on pig carcasses. Because risk difference is a parameter sensitive to the differences across studies in carcass swab areas and Salmonella detection methods, its meta-analysis highly reflected this heterogeneity (P < 0.001). However, parameterization of relative risk, not being biased by the above sources of variability, did not give rise to heterogeneity among studies and produced a fixed-effects meta-analysis solution, which is deemed more suitable for compilations based on a small number of individual studies (n = 9). Because of the systematic approach of meta-analysis (i.e., individual studies are weighed according to precision) and its reliance for actual data, the output distribution of the relative risk effect size (approximately eN(-0.868,0.166)) merits consideration for inclusion in the chilling stage of quantitative risk assessments modeling the prevalence of this pathogen along the pork production chain.

Prevalence and numbers of Salmonella spp. and Enterobacteriaceae on pork cuts in abattoirs in the Republic of Ireland.

AIMS: This study aimed to determine the numbers and types of Salmonella spp. and Enterobacteriaceae on pork cuts in the meat cutting room environment of four commercial pork abattoirs in the Republic of Ireland. METHODS AND RESULTS: Pork oysters (M. gluteus medius; n = 720) and swabs (n = 56) from equipment and surfaces were screened for Salmonella spp. using a DNA-based PCR method and confirmed by culture. Salmonella numbers were assessed using a three-tube most probable number (MPN) technique. Salmonella spp. was detected on 24/720 (3.3%) pork cuts (range of <0.03-0.36 MPN g(-1)) and in 7/56 (12.5%) environmental swabs (range of <0.03-1.10 MPN cm(-2)). There was significant variation in the prevalence of Salmonella on pork between different abattoirs and days of sampling (range of 0-31.7%). The predominant serotype was Salmonella serotype Typhimurium followed by Salmonella serotype Derby. CONCLUSIONS: Overall prevalence data conceal the key finding that there was considerable variation in the incidence of Salmonella on different days. A direct association between Salmonella contamination of pork cuts and equipment/surfaces was observed. SIGNIFICANCE AND IMPACT OF THE STUDY: Prevalence and numbers of Salmonella were low; however, results clearly demonstrate the potential for cross-contamination from equipment and meat contact surfaces in the cutting room environment.