Minced Pork Meat Research Articles

Evaluation of Scenarios for Reducing Human Salmonellosis Through Household Consumption of Fresh Minced Pork Meat

Nontyphoidal salmonellosis is the second most frequently reported zoonotic disease in the European Union (EU) and is considered to be a major threat to human health worldwide. The most reported Salmonella serovar in the EU is S. Enteritidis, mainly associated with egg contamination, followed by S. Typhimurium, with the latter being the most predominant serovar isolated from pork. These findings suggest that reducing the Salmonella contamination in the pork production might be a good strategy to prevent and control human salmonellosis in the EU. Recently, a quantitative microbial risk assessment (QMRA) has been developed to assess the risks for human salmonellosis due to home consumption of fresh minced pork meat in Belgium. The newly developed risk model is called the METZOON model. In the current study, the METZOON model was used to evaluate the effectiveness of different hypothetical Salmonella mitigation strategies implemented at different stages of the minced pork production and consumption chain by means of a scenario analysis. To efficiently evaluate the mitigation strategies, model results were obtained by running simulations using the randomized complete block design. The effectiveness of a mitigation strategy is expressed using point and interval estimates of the effect size for dependent observations, expressed as the standardized difference in population means. The results indicate that the most effective strategies are taken during the slaughter processes of polishing, evisceration, and chilling, and during postprocessing, whereas interventions in the primary production and at the beginning of the slaughter process seem to have only a limited effect. Improving consumer awareness is found to be effective as well.

NUSAP: a method to evaluate the quality of assumptions in quantitative microbial risk assessment

The Numeral Unit Spread Assessment Pedigree (NUSAP) system was implemented to evaluate assumptions in a quantitative microbial risk assessment (QMRA) model for Salmonella spp. in minced pork meat. This QMRA model allows the testing of mitigation strategies for the reduction of human salmonellosis and aims to serve as a basis for science‐based policy making. The NUSAP method was used to assess the subjective component of assumptions in the QMRA model by a set of four pedigree criteria: ‘the influence of situational limitations’, ‘plausibility’, ‘choice space’ and ‘the agreement among peers’. After identifying 13 key assumptions relevant for the QMRA model, a workshop was organized to assess the importance of these assumptions on the output of the QMRA. The quality of the assumptions was visualized using diagnostic and kite diagrams. The diagnostic diagram pinpointed assumptions with a high degree of subjectivity and a high ‘expected influence on the model results’ score. Examples of those assumptions that should be dealt with care are the assumptions regarding the concentration of Salmonella on the pig carcass at the beginning of the slaughter process and the assumptions related to the Salmonella prevalence in the slaughter process. The kite diagrams allowed a clear overview of the pedigree scores for each assumption as well as a representation of expert (dis)agreement. The evaluation of the assumptions using the NUSAP system enhanced the debate on the uncertainty and its communication in the results of a QMRA model. It highlighted the model’s strong and weak points and was helpful for redesigning critical modules. Since the evaluation of assumptions allows a more critical approach of the QMRA process, it is useful for policy makers as it aims to increase the transparency and acceptance of management decisions based on a QMRA model.

Assessing interventions by quantitative risk assessment tools to reduce the risk of human salmonellosis from fresh minced pork meat in Belgium.

The risk of human salmonellosis through the consumption of minced pork meat in Belgium was assessed via a modular risk model covering pork meat production from lairage to human consumption. The main goal of the model was to give concrete options to reduce effectively the risk of human salmonellosis through the consumption of minced pork meat. These options (scenarios) were elaborated with reference to the international situation and the literature to give concrete and realistic possibilities for improving the microbiological quality of pork meat and to reduce the number of human salmonellosis cases per year in Belgium. The model estimates 15,376 cases of human salmonellosis per year in Belgium due to the consumption of minced pork meat. The results of the scenarios showed that the risk of human salmonellosis could be significantly reduced by efforts all along the pork meat production chain but also by efforts made by consumers. The responsibility of food business operators for the pork meat production chain is high in relation to the microbiological quality of meat delivery, especially at the slaughterhouse. Consumers also need to be aware of good hygiene practices during preparation of the meat at home. Cross-contamination with raw food can be avoided by changing the habits and the behavior of the household cook. The results of these scenarios would be useful for the food business operators involved in the pork meat chain and for public health authorities.

Expert judgement in a risk assessment model for Salmonella spp. in pork: The performance of different weighting schemes

A structured expert judgement study was carried out in order to obtain input parameters for a quantitative microbial risk assessment (QMRA) model. This model aimed to estimate the risk of human Salmonella infections associated with the consumption of minced pork meat. Judgements of 11 experts were used to derive subjective probability density functions (PDFs) to quantify the uncertainty on the model input parameters.The performance of experts as probability assessors was measured by the experts’ ability to correctly and precisely provide estimates for a set of seed variables (=variables from the experts’ area of expertise for which the true values were known to the analyst). Subsequently different weighting schemes or “decision makers” (DMs) were applied using Cooke's classical model in order to obtain combined PDFs as a weighted linear combination of the expert's individual PDFs.The aim of this study was to compare the performance of four DMs namely the equal weight DM (each expert's opinion received equal weight), the user weight DM (weights are determined by the expert's self-perceived level of expertise) and two performance-based DMs: the global weight DM and the item weight DM. Weights in the performance-based DMs were calculated based on the expert's calibration and information performance as measured on the set of seed variables.The item weight DM obtained the highest performance with a calibration score of 0.62 and an information score of 0.52, as compared to the other DMs. The weights of the performance-based DMs outperformed those of the best expert in the panel. The correlation between the scores for self-rating of expertise and the weights based on the experts’ performance on the calibration variables was low and not significant (r=0.37, p=0.13).The applied classical model provided a rational basis to use the combined distributions obtained by the item weight DM as input in the QMRA model since this DM yielded generally more informative distributions for the variables of interest than those obtained by the equal weight and user weight DM. Attention should be paid to find adequate and relevant seed variables, since this is important for the validation of the results of the weighting scheme.

Development of a Quantitative Microbial Risk Assessment for Human Salmonellosis Through Household Consumption of Fresh Minced Pork Meat in Belgium

A quantitative microbial risk assessment (QMRA) according to the Codex Alimentarius Principles is conducted to evaluate the risk of human salmonellosis through household consumption of fresh minced pork meat in Belgium. The quantitative exposure assessment is carried out by building a modular risk model, called the METZOON-model, which covers the pork production from farm to fork. In the METZOON-model, the food production pathway is split up in six consecutive modules: (1) primary production, (2) transport and lairage, (3) slaughterhouse, (4) postprocessing, (5) distribution and storage, and (6) preparation and consumption. All the modules are developed to resemble as closely as possible the Belgian situation, making use of the available national data. Several statistical refinements and improved modeling techniques are proposed. The model produces highly realistic results. The baseline predicted number of annual salmonellosis cases is 20,513 (SD 9061.45). The risk is estimated higher for the susceptible population (estimate 4.713 x 10(-5); SD 1.466 x 10(-5)) compared to the normal population (estimate 7.704 x 10(-6); SD 5.414 x 10(-6)) and is mainly due to undercooking and to a smaller extent to cross-contamination in the kitchen via cook's hands.

NUSAP Method for Evaluating the Data Quality in a Quantitative Microbial Risk Assessment Model forSalmonellain the Pork Production Chain

The numeral unit spread assessment pedigree (NUSAP) system was implemented to evaluate the quality of input parameters in a quantitative microbial risk assessment (QMRA) model for Salmonella spp. in minced pork meat. The input parameters were grouped according to four successive exposure pathways: (1) primary production (2) transport, holding, and slaughterhouse, (3) postprocessing, distribution, and storage, and (4) preparation and consumption. An inventory of 101 potential input parameters was used for building the QMRA model. The characteristics of each parameter were defined using a standardized procedure to assess (1) the source of information, (2) the sampling methodology and sample size, and (3) the distributional properties of the estimate. Each parameter was scored by a panel of experts using a pedigree matrix containing four criteria (proxy, empirical basis, method, and validation) to assess the quality, and this was graphically represented by means of kite diagrams. The parameters obtained significantly lower scores for the validation criterion as compared with the other criteria. Overall strengths of parameters related to the primary production module were significantly stronger compared to the other modules (the transport, holding, and slaughterhouse module, the processing, distribution, and storage module, and the preparation and consumption module). The pedigree assessment contributed to select 20 parameters, which were subsequently introduced in the QMRA model. The NUSAP methodology and kite diagrams are objective tools to discuss and visualize the quality of the parameters in a structured way. These two tools can be used in the selection procedure of input parameters for a QMRA, and can lead to a more transparent quality assurance in the QMRA.

Validation of a same-day real-time PCR method for screening of meat and carcass swabs for Salmonella

BackgroundOne of the major sources of human Salmonella infections is meat. Therefore, efficient and rapid monitoring of Salmonella in the meat production chain is necessary. Validation of alternative methods is needed to prove that the performance is equal to established methods. Very few of the published PCR methods for Salmonella have been validated in collaborative studies. This study describes a validation including comparative and collaborative trials, based on the recommendations from the Nordic organization for validation of alternative microbiological methods (NordVal) of a same-day, non-commercial real-time PCR method for detection of Salmonella in meat and carcass swabs.ResultsThe comparative trial was performed against a reference method (NMKL-71:5, 1999) using artificially and naturally contaminated samples (60 minced veal and pork meat samples, 60 poultry neck-skins, and 120 pig carcass swabs). The relative accuracy was 99%, relative detection level 100%, relative sensitivity 103% and relative specificity 100%. The collaborative trial included six laboratories testing minced meat, poultry neck-skins, and carcass swabs as un-inoculated samples and samples artificially contaminated with 1–10 CFU/25 g, and 10–100 CFU/25 g. Valid results were obtained from five of the laboratories and used for the statistical analysis. Apart from one of the non-inoculated samples being false positive with PCR for one of the laboratories, no false positive or false negative results were reported. Partly based on results obtained in this study, the method has obtained NordVal approval for analysis of Salmonella in meat and carcass swabs. The PCR method was transferred to a production laboratory and the performance was compared with the BAX Salmonella test on 39 pork samples artificially contaminated with Salmonella. There was no significant difference in the results obtained by the two methods.ConclusionThe real-time PCR method for detection of Salmonella in meat and carcass swabs was validated in comparative and collaborative trials according to NordVal recommendations. The PCR method was found to perform well. The test is currently being implemented for screening of several hundred thousand samples per year at a number of major Danish slaughterhouses to shorten the post-slaughter storage time and facilitate the swift export of fresh meat.

Kinetic migration studies from packaging films into meat products

One of the main concerns regarding safety of food packaging is the possible migration of chemical substances (monomers and other starting substances, additives, residues) from food contact materials into foods. To evaluate the effect of the fat content and of the temperature of storage on the migration from plastics packaging films into meat products as an important class of foodstuffs, the kinetic mass transport of a model migrant (diphenylbutadiene) from low density polyethylene (LDPE) film in contact with different meat products was investigated. From the data, the diffusion coefficients were calculated for the applied test conditions, by use of a mathematical model. The results showed that migration increased with fat content and storage temperature. Analysis of migration data corresponding to minced pork meat containing different amounts of fat, stored for 10 days at 25 °C, revealed an excellent relationship between migration level and fat content. This behaviour was also found for other types of meat products (chicken and pork neck). A simplifying mathematical model was applied to derive effective diffusion coefficients in the polymer which, however, do take kinetic effects in the meat also into account. In the case of pork meat contact, the effective diffusion coefficients derived from mathematical modelling were ten times higher for storage at 25 °C (1.88 × 10 −9 cm 2 s −1) than for storage at 5 °C (1.2 × 10 −10 cm 2 s −1).

The effect of the high hydrostatic pressure technology on livestock products monitored by NIR spectroscopy and chemosensor array

Experiments were performed to study the effects of high hydrostatic pressure (HHP) and gamma irradiation, respectively, from two aspects. The effects of HHP treatments on minced pork meat exposed to 50–800 MPa for 20 min and stored at 4 °C for a period of 1 week were examined. The immediate effects of HHP on egg white samples were compared to that of irradiation. Egg white samples were subjected to irradiation (3 kGy) and HHP treatment (400 MPa, 5 min) and measured immediately after treatments. The recorded electronic nose data and near infrared spectra were evaluated using different methods of multivariate qualitative analyses.

Measurement of lipid oxidation and porphyrins in high oxygen modified atmosphere and vacuum-packed minced turkey and pork meat by fluorescence spectra and images

This paper illustrates that fluorescence spectroscopy and imaging can be used to measure the extent and distribution of lipid oxidation in meat. Minced turkey thighs and pork semimembranosus muscles were stored for 7 and 12 days at 4 °C in high oxygen (O 2) modified atmosphere packages and vacuum. Turkey meat packed in high O 2 atmosphere was oxidised already after 7 days of storage. The sensory rancid odour score was 4.7 (on a scale from 1 to 9) and the TBARS value was 1.86 mg MDA/kg. There was also an increase in fluorescence emission intensity in the 410–550 nm region, which arises from lipid oxidation products. The combination of unsaturated fatty acids and access to O 2 resulted in lipid oxidation gradients in the turkey meat samples, and these gradients were clearly visualised by fluorescence images. In comparison, pork meat was more stable against lipid oxidation, with TBARS values <0.2 mg MDA/kg and no development of fluorescent lipid oxidation products was detected. The fluorescence spectra measured in the present experiment suggest that turkey thighs and pork semimembranosus muscle in addition to protoporphyrin also have a natural content of Zn protoporphyrin. The porphyrin content was higher in pork meat than in turkey meat. It increased during storage time when the meat was packed in vacuum, and it decreased with O 2 availability. The distribution of porphyrins in the meat was visualised by fluorescence imaging.

Determination of total fat and moisture content in meat using low field NMR

The use of low field Nuclear Magnetic Resonance (LF-NMR) is shown to be a fast and accurate alternative to the use of drying and solvent extraction, to determine the content of raw or total fat and moisture in a biological system. The proposed NMR method for fat determination in minced meat proves to be a robust method that does not require sophisticated post handling of the experimental data. The calibration procedure is very easy, as a calibration value from a sample of known weight containing 100% oil is the only calibration needed for the proposed experimental set-up. On three sets, each containing 42 samples of minced beef where the fat content varies from less than 1 to 14%, the fat content has been measured either by NMR on fresh tissue, NMR on dried tissue, or by the use of solvent extraction determining the content of raw fat [Foss-let fat analyser (AOAC Official Method 976.21]. Comparison of the three methods for determination of the fat content shows satisfactory agreement between the different methods. On six samples of minced pork meat, the fat and moisture content have been determined. The total fat content was determined by NMR both on fresh and dried tissue. The moisture content was determined by NMR of fresh tissue and by drying of the tissue. The different methods for determining fat and moisture content agreed for the minced pork samples.

Reduction of Bacillus subtilis, Bacillus stearothermophilus and Streptococcus faecalis in meat batters by temperature-high hydrostatic pressure pasteurization

People have a growing preference for fresh, healthy, palatable and nutritious meals and drinks. However, as food deterioration is a constant threat along the entire food chain, food preservation remains as necessary now as in the past. High pressure processing is one of the emerging technologies being studied as an alternative to the classical pasteurization and sterilization treatments of food. Samples of fried minced pork meat were inoculated with strains of Streptococcus faecalis and with sporulating microorganisms like Bacillus subtilis and stearothermophilus. The samples were subjected to several combined temperature-high pressure treatments predicted by the mathematical model applied in Response Surface Methodology. Using the “Box–Behnken” concept, the number of tests for a whole area of pressure–temperature–time-combinations (pressure variation: 50–400 MPa, temperature variation 20–80°C, time variation 1–60 min) could be limited to 15. In the center point of the model, the experimental combination was performed in triple to estimate the experimental variance. All the tests were executed in a randomized order to exclude the disturbing effect of environmental factors. Microbial analysis revealed for each microorganism an important reduction in total plate count, demonstrating a superior pressure resistance of the sporulating microorganisms in comparison with the most pressure resistant vegetative species Streptococcus faecalis. The effect of the medium composition could be neglected, showing little protective effect of, e.g. the fat fraction as seen in heat preservation techniques.

Application of Enterocins as Biopreservatives against Listeria innocua in Meat Products

The antilisterial effect of enterocins A and B in meat and meat products (cooked ham, minced pork meat, deboned chicken breasts, pâté, and slightly fermented sausages [espetec]) have been shown. An infective dose of 5 to 10 most probable numbers (MPN)/g to simulate the counts of Listeria generally found in meat products was used. Enterocins at 4,800 AU/g reduced the numbers of Listeria innocua by 7.98 log cycles in cooked ham and by 9 log cycles in pâté when stored at 7°C for 37 days. In deboned chicken breasts stored at 7°C for 7 days, 4,800 AU/cm2 of enterocins diminished the L. innocua counts in 5.26 log cycles when compared to the control batch. In minced pork meat held at 7°C for up to 6 days, 1,600 AU/g kept L. innocua counts under 3 MPN/g, while the control batch reached 50 CFU/g. In espetec sausages, 648 AU/g diminished the number of L. innocua under 50 CFU/g from the fifth day until the end of the process (12 days) while the control batch kept the initial counts (3 × 104 CFU/g). This is the first report on enterocins showing an antilisterial effect in different types of meat products.

Mechanically recovered poultry meat sausages manufactured with high hydrostatic pressure

The effect of high pressure processing at high temperature on texture and color of frankfurter-type sausages made with different contents of mechanically recovered poultry meat (MRPM) was evaluated and compared with that of a standard cooking process. Five types of sausages containing 100, 75, 50, 25, and 0% MRPM and 0, 25, 50, 75, and 100% of minced pork meat (MPM), respectively, were manufactured. They were pressurized at 500 MPa for 30 min at 50, 60, 70, and 75 C or cooked at 75 C for 30 min. Pressure-treated sausages were less springy and firm, but more cohesive. Moreover, color of pressurized sausages was lighter and more yellow than that of conventionally cooked sausages. Addition of MPM increased cohesiveness, hardness, and force at 80% compression. Minced pork meat also caused the appearance of sausages to be lighter, less red, and less yellow. Cooked sausages made with MRPM can have an attractive appearance and texture via high pressure processing.

The influence of the anticaking agent potassium ferrocyanide and salt on the oxidative stability of frozen minced pork meat

The anticaking agent potassium ferrocyanide, K 4Fe(CN) 6, was found to affect lipid oxidation in frozen, minced pork meat both in ‘normal’ concentrations, when added together with food grade salt to yield 2 % NaCl in the product, and in ‘unrealistic’ high concentrations added separately or together with analytical grade salt. The level of K 4Fe(CN) 6 obtained from adding 2 % food grade salt accelerated the development of lipid hydroperoxides, but affected the development of TBARS to a lesser degree. High level of K 4Fe(CN) 6 seems to protect hydroperoxides from degradation to secondary lipid oxidation products measured as TBARS. The use of salt with the anticaking agent, K 4Fe(CN) 6, in meat processing should be reconsidered for each product since it may enhance lipid oxidation. A mechanism for mediation by the Fe(CN) 6 4− Fe(CN) 6 3− redox couple of pigment-catalysed lipid oxidation is suggested, based on an observed correlation between oxymyoglobin oxidation (measured as tristimulus colorimetric parameter, a) and lipid oxidation (measured as TBARS) for the frozen pork patties.

The combined effect of rosemary (Rosmarinus officinalis L.) and modified atmosphere packaging as protection against warmed over flavour in cooked minced pork meat

Rosemary (dried leaves ofRosmarinus officinalis L.) added to cooked meat balls (minced pork) was found to retard the formation of warmed over flavour (WOF) during chill storage. The spice was added to pork meat (Longissimus dorsi) balls in an amount acceptable for the product, as evaluated by a sensory panel (0.05% of total weight). After cooking (water bath, internal temperature 80°C), the meat balls were packed using five atmosphere packaging conditions: (i) air; (ii) 5% O2/95% N2; (iii) 3% O2/97% N2; (iv) 1% O2/99% N2; and (v) 100% N2. During chill storage (5°C), the sensory quality of the reheated meat balls was evaluated by a trained sensory panel, and lipid oxidation was followed by measurement of thiobarbituric acid reactive substances (TBARS). The combination of decreased O2 atmosphere in the packages and addition of rosemary resulted in a significantly (p<0.05) lower amount of TBARS and a significantly (p<0.05) better sensory score.

Antimicrobial Activity of Some Plant Essential Oils Against Listeria monocytogenes

The antimicrobial activity of 32 plant essential oils commonly used in food industry was examined against four strains of Listeria monocytogenes and one strain of Listeria innocua. Two different procedures were carried out to test the essential oils, a paper disc diffusion method and an inhibition curve. In the former procedure an absolute ethanolic solution (1:5 v/v) of each oil was tested on the plates inoculated with a bacterial concentration of 106 CFU/ml. Five of the 32 essential oils (cinnamon, clove, origanum, pimento, and thyme) showed antibacterial activity. Some of the five oils were also tested at lower concentration (1:50 v/v). The inhibition curve to study antilisteric efficacies of the five oils in a saline solution system was examined. Pimento oil showed marked and rapid activity (generally within 1 h of exposure), whereas clove, origanum, and thyme oils showed a more slow activity. The antilisteric activity of the tested oils seems to be strain dependent. A L. monocytogenes strain was also tested in a food matrix (minced pork meat) against thyme essential oil. Minced pork meat with thyme oil reduced the L. monocytogenes population by ca. 100-fold over the first week of storage.

The incidence of Listeria spp. in faeces of Danish pigs and in minced pork meat

One hundred and seventy-two samples of pig faces, collected at a slaughterhouse, were investigated for Listeria species. Three of the samples (1.7%) contained L. monocytogenes, while L. innocua was demonstrated in four other samples. The 172 samples represented pigs from 72 herds, 14 (19%) of which were SPF herds. Listeria was not demonstrated in any of the samples from the SPF herds representing 24% of all samples investigated. This indicates that the incidence of L. monocytogenes in SPF herds might be very low. In 51 samples of minced pork, Listeria spp. were demonstrated in 32 samples, L. monocytogenes in six samples, L. innocua in 26 samples, and L. seeligeri in one sample. In comparison with similar findings in cattle faeces and minced beef, the conclusion was drawn that faecal contamination may play an important rôle in the dissemination of L. monocytogenes in raw meats.

THE EFFECT OF LOW TEMPERATURES ON THE INACTIVATION BY IONIZING RADIATIONS OF CLOSTRIDIUM BOTULINUM SPORES IN MEAT

SUMMARYThe effect of temperature on the inactivation of Clostridium botulinum spores has been studied in minced pork meat irradiated with 2 MeV electrons and gamma rays. When electrons were used, differences in survival after 1 Mrad at 18°, 0° and — 75° were small and were significant only when temperatures of 0° and 18° were compared, a slightly higher survival being obtained at 0°. The effects at temperatures of 0° and —75° were further compared, using a range of gamma ray doses, and regression lines were calculated for the inactivations. From these, ‘sterilizing doses’, i.e. those which would give a survivor level of 10‐12, were calculated, together with their 95% confidence limits. The errors involved in this type of estimate are discussed: it is concluded that there is no evidence of a significant difference in the computed sterilizing doses at 0° and at —75°.