A meta-analysis of the effect of pasture access on the lipid content and fatty acid composition of lamb meat

A meta-analysis on the influence of the pasture on the lipid content and fatty acid profile in lamb meat was conducted. A total of 20 studies were selected and data on total lipid content, saturated, mono- and polyunsaturated fatty acids in lamb meat were extracted for two population groups, indoors, and pastured. Due to the high between-study heterogeneity, separate random-effects models were applied to the raw mean difference (effect size parameterization) for each of the outcomes. The results of the meta-analysis pointed that access to pasture tended to decrease the fat content in lamb, while increasing the saturated fatty acids (P < 0.05). The amounts of monounsaturated and n-6 polyunsaturated fatty acids were decreased (P < 0.05). On the other hand, grazing led to substantial increase in the content of n-3 polyunsaturated fatty acids, and decrease (P < 0.01) of the ratio n-6/n-3 in lamb meat, thus suggesting that pasture rearing can be recommended for improvement of meat dietetic quality.by the Erasmus + Programme, Key Action 1: Learning mobility for individuals, administered by the European Union (№ 2014-1- BG01-KA103-000110). Dr. Gonzales-Barron wishes to acknowledge the financial support provided by the Portuguese Foundation for Science and Technology (FCT) through the award of five-year Investigator Fellowship (IF) in the mode of Development Grants (IF/00570).info:eu-repo/semantics/publishedVersio

Conducting inferential statistics for low microbial counts in foods using the Poisson-gamma regression

Mixed Poisson distributions have been shown to be able to represent low microbial counts more efficiently than the lognormal distribution because of its greater flexibility to model microbial clustering even when data consist of a large proportion of zero counts. The objective of this study was to develop an alternative modelling framework for low microbial counts based on heterogeneous Poisson regressions. As an illustration, Poisson-gamma regression models were used to assess the effect of chilling on the concentration of total coliforms from beef carcasses (n=600) sampled at eight large Irish abattoirs. Three Poisson-gamma and three zero-modified (hurdle and zero-inflated) models were appraised with a series of random-effects variants in order to extract any variability in microbial mean concentration, dispersion and/or proportion of zero counts. Models were compared and validated in their ability to predict the coliforms counts on carcasses after chilling. In all five test batches, the hurdle Poisson-gamma distributions predicted the observed post-chill counts closer than the Poisson-gamma distributions. This is justified by the better capacity of the hurdle model to represent a higher proportion of zero counts, which were in fact observed in the post-chill batches. Thus, with a coded variable (pre-chill/post-chill) as treatment, and extracting the significant variability of batches nested in abattoirs for the coliforms mean concentration (σ 2 u =2.68), the dispersion measure (σ 2 v =2.39) and the probability of zero counts (σ 2 w =0.89), the validated hurdle Poisson-gamma model confirmed that chilling has a decreasing effect on the viability of coliforms from beef carcasses, and that the concentration is reduced by an average (pre-chill to post-chill) factor of 2.2 (95% CI: 2.15-2.24) at batch level. The model also indicated that chilling increases the odds of producing a zero count from a carcass swab in about 13.5 times, and that the higher the coliforms concentration in a batch, the weaker the effect that chilling has to reduce such contamination on the beef carcasses.info:eu-repo/semantics/publishedVersio

Operating characteristic curves for single, double and multiple fraction defective sampling plans developed for Cronobacter in powder infant formula

AbstractThe microbiological criteria established in the EC 2073/2005 for Cronobacter in powder infant formula (PIF) are based on two-class attribute sampling plans, where the sample results are qualitative (sample indicates presence or absence) and the lot is rejected if any sample is positive. The performance of a sampling plan is revealed by its Operating Characteristic (OC) curve which plots the probability of acceptance against possible values of proportion defective. The objective of this study is to generate several OC curves for single, double and multiple sampling plans assuming different statistical distributions of Cronobacter in PIF in order to determine and compare the probabilities of rejecting/accepting the lot and the respective level of contamination. In this study, the microbial distribution of Cronobacter in the PIF is described by assuming to be Poisson-lognormal (PLN), Poisson-gamma (PG), Zero- inflated Poisson-lognormal (ZIPLN) and Zero-inflated Poisson-gamma (ZIPG). For each distribution the proportion defective of the population is estimated in order to determine the probability of acceptance for single, double and multiple sampling plans. Furthermore, the effect of clustering of the bacteria on the probability of acceptance of the lot was assessed through a Poisson-logarithmic (PLOG) and a PLogn distribution. Probabilities of accepting the lot at a given level of contamination change drastically according to the statistical distribution assumed and by changing the values of its own parameters. In addition, a procedure of multiple sampling plan based on resampling reveals that the producer's risk (α risk) can be reduced without affecting the consumer's risk (β risk)

11th International Conference on Predictive Modelling in Food: book of abstracts

It is our great pleasure to welcome you in Bragança, Portugal, for the 11th International Conference of Predictive Modelling in Food (ICPMF11). Since 1992, ten ICPMF editions have taken place, providing a forum for the exchange of ideas, identification of research needs and novel approaches for the advancement of predictive modelling towards ensuring safety and quality of foods. Bragança is a typically-Portuguese old town (Romanic origin dates back to the 10th century), located by the Natural Park of Montesinho – one of the wildest forest zones of Europe – and the Douro Valley – the third oldest protected wine region in the world; and surrounded by traditional villages of a distinctive rustic beauty. Bragança houses several traditional industries producing a myriad of local foods, such as cheese, fermented meats, wine, chestnuts and honey, which provide substantial economic sustainability to the region. ICPMF11 reunites food researchers, stakeholders, risk assessors and users of predictive models to present recent developments and trends in modelling approaches for food quality, safety and sustainability. We succeeded to gather a significant number of delegates from over the world to participate in a comprehensive scientific programme that includes keynote lectures, oral communications and posters, allocated in sessions focusing on: . Advances in predictive microbiology modelling . Predictive modelling in innovative food processing and preservation technologies . Advances in microbial dynamics and interactions . Advances in software and database tools . Meta-analysis protocols and applications . Advances in risk assessment methods and integration of omics techniques . Advances in predictive modelling in food quality and safety . Predictive mycology . Individual cell and whole-cell modelling Apart from those, ICPMF11 features for the first time a special session dedicated to “Innovative approaches for ensuring safety of traditional foods” and the Round Table: “Assuring the Safety of Traditional Foods: A Scientific Contribution to Protecting our Cultural Heritage”. We, as food researchers based in a Mediterranean mountain region, are aware that the production of traditional foods plays a key role in the development of rural regions, since the agricultural commodities used as raw materials are generally produced locally, allowing and stimulating local commercialisation, thus contributing to a sustainable environment, and employment in rural populations. It was inspiring for us to have received many submissions from both developed and developing countries on the valorisation of traditional foods through the application of up-to-date modelling research. Besides that, one morning workshop and three afternoon tutorials were programmed during the day before the scientific programme. The workshop “How to benefit from the Risk Assessment Modelling and Knowledge Integration Platform (RAKIP)” was organised by Matthias Filter. The parallel tutorials “Towards an integrated predictive software map: Practical examples of use of predictive microbiology software tools for food safety and quality”; “Advanced methods in predictive microbiology” and “Topics in quantitative microbial risk assessment using R” were organised by Fernando Pérez-Rodríguez, Pablo Fernández, Alberto Garre and Mariem Ellouze; by Lihan Huang, Cheng-An Hwang and Vasco Cadavez; and by Patrick Njage and Ana Sofia Ribeiro Duarte, respectively. We thank these organisers for their proposals. Abstracts, reviewed by the ICPMF11 Scientific Committee, are published in the present Book of Abstracts while peer-reviewed original research articles will be invited to be published in ICPMF11 Special Issues in the International Journal of Food Microbiology and Microbial Risk Analysis. To stimulate the participation of postgraduate students and young researchers, two kinds of awards were arranged: the Young Researcher Best Oral Presentation prizes, sponsored by Elsevier; and the Developing Scientist Best Poster prizes, sponsored by the International Committee on Food Microbiology and Hygiene (ICFMH) of the International Union of Microbiological Societies (IUMS). For the first time, this ICPMF edition gives out two awards for the Senior Researcher Best Oral Presentation, sponsored by the open-access journal Foods – MDPI. In addition to the scientific programme, we prepared an exciting social programme for delegates to appreciate the rich culture, gastronomy and traditions of Bragança, w includes welcome reception, live music, tasting of regional food and a gala dinner in the Castle of Bragança. We look forward to lively discussions, and hope that this meeting will give you the opportunity to strengthen friendship and cooperation, and build new contacts for future research endeavours.info:eu-repo/semantics/publishedVersio

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 ± 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.The authors are grateful to the support from the’Associação de Criadores de Bovinos de Raça Mirandesa’ for kindly providing the meat samples and’Terra Fria Carnes' for putting their slaughterhouse facilities at our disposal during the experimental trials.info:eu-repo/semantics/publishedVersio

A Bayesian approach to estimating the uncertainty in the distribution of Cronobacter spp. in powdered infant formula arising from microbiological criteria test outcomes

The application of microbiological criteria related to foods has become well established for the protection of public health. Sampling plans will more likely detect a microorganism when the level of contamination is high. However, as the concentration of the microorganism drops, detection becomes more and more infrequent. Cronobacter spp. is an opportunistic pathogen that can occur infrequently and in low concentrations in powdered infant formula (PIF) with a distribution that is typically heterogeneous. This paper developed a Bayesian approach to quantify the uncertainty in the concentration of Cronobacter spp. clusters that may be present in a batch of PIF depending on the outcome of a sampling plan. Two approaches were developed. The first was a Bayesian methodology using a spreadsheet approach to develop the appropriate likelihood and posterior distributions based on an uninformed prior distribution. The second approach was similar but used an algebraic approach rather than a spreadsheet numerical approximation to characterise the uncertainty. Different sampling plans were considered based on the EC Microbiological Criteria for Cronobacter spp. When a zero positive test was the outcome of the sampling plans considered, the Bayesian analysis indicated that while the most likely outcome for all the sampling plans considered was zero clusters present, the analysis indicated that the true number of clusters present could be as high as several thousand clusters per tonne of powder depending on the sampling plan. The algebraic approach demonstrated that for zero or one positive tests, the uncertainty distribution could be approximated by a gamma distribution. Choice of the prior distribution influenced the level of uncertainty. The Bayesian approach demonstrates that even when zero positives are detected for a given sampling plan, there remains a considerable uncertainty in the true number of microorganisms that may be present undetected in a consignment of powder.This work was funded under the Irish Department of Agriculture, Food and the Marine Food Institutional Research Measure (Research contract number13/F/423).info:eu-repo/semantics/publishedVersio

Thermal inactivation kinetics of Salmonella typhimurium in alheira sausage batter

The objective of this work was to characterise the heat resistance of Salmonella typhimurium (ST) in alheira sausage batter. Two batches of alheira batter were obtained from a producer and inoculated with an ST overnight culture to reach ~7.0 log CFU/g in alheira batter. Bags containing well-spread 10 g alheira batter were submitted in duplicate to temperatures of 63, 60, 57 and 54 °C in an immersion bath. A log-linear primary model fitted to each of the inactivation curves estimated the death rates of ST in alheira batter with coefficients of determination ranging between 0.914 and 0.987. Through a Bigelow model, the D-value was modelled as a function of temperature, resulting in a log D (Tref = 50 °C) of 2.302 (SE = 0.304), corresponding to 200 min at 50 °C to reduce ST in 1 log, and a z-value of 5.016 (SE = 0.839) °C.The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) for financial support through national funds FCT/MCTES (PIDDAC) to CIMO (UIDB/00690/2020 and UIDP/00690/2020) and SusTEC (LA/P/0007/2021). The authors are also grateful to the EU PRIMA programme, the Portuguese Foundation for Science and Technology (FCT) for funding the ArtiSaneFood project (PRIMA/0001/2018).info:eu-repo/semantics/publishedVersio

Modelling the effect of chilling on the occurrence of Salmonella on pig carcasses at study, abattoir and batch levels by meta-analysis

The effect of chilling on the occurrence of Salmonella on pig carcasses was investigated at study, abattoir and batch level by meta-analysis. Both the fixed-effects and random-effects model confirmed (p b 0.05) the significant effect of chilling in decreasing Salmonella occurrence on pig carcasses; although the random-effects solution was preferred to account for the significant variability in effect size (p b 0.001) estimated from the 13 primary studies considered, the 32 abattoirs surveyed, and the 51 sampled batches. Conservatively, it can be said that chilling reduces the Salmonella incidence on pig carcasses by a mean ratio of ~1.6 (95% CI: 1.0–2.6). Multilevel meta-analysismodels investigating study characteristics that could explain the heterogeneity (τ2) in the true effect size among primary studies (τ2 = 0.578), among surveyed abattoirs (τ2 = 0.431), and among sampled batches (τ2 = 0.373), revealed that study size (represented by the moderating variables of ‘total sample size’ and ‘number of batches sampled in an abattoir’) and ‘carcass swabbed area’ have a significant impact (p b 0.05) on the measured effect size of chilling. The fact that swabbed area explained between 56 and 62% and total sample size between 23 and 38% of the total heterogeneity in the chilling true effect size, indicates that differences in experimental design greatly affect our substantive conclusion about the effect of chilling on Salmonella occurrence. This inconsistency to elucidate the effect of chilling arises because of themany factors influencing both the performance of the chilling operation and themeasurement itself.Meta-analysis was not only instrumental to showthat small-size studies (i.e., only one batch sampled per abattoir, total number of sampled carcasses per batch b 50) and small swabbed areas (b100 cm2) lead to imprecise and even conflicting conclusions, but most importantly, enabled definition of the characteristics of a well-designed study having aminimumstatistical power to produce precise results. A sound experimental design derived by multilevel meta-analysis consists of swabbing carcass areas of at least 500 cm2 from 25 pre-chill and 25 post-chill carcasses from a single production batch, with a minimum of two batches sampled per surveyed abattoir. If the survey were to be conducted in more than one abattoir, the total sample size should not be less than 400. Two methods to test for publication bias, a common problem in meta-analysis, suggested that whilst the presence of unpublished small-size studies is probable, it is not likely that this would significantly bias the overall chilling effect estimated in this study

Modelling beef meat quality traits during ageing by early post-mortem pH decay descriptors

Previous work has demonstrated that beef carcasses can be promptly and accurately classified into optimal quality and cold-shortened in accordance to the concept of pH/temperature ‘ideal window’ by using carcass characteristics and early post-mortem pH/temperature decay descriptors. The objective of this study was to assess the combined effects of the aforementioned variables on the two main eating quality attributes of meat – namely, tenderness (measured as shear force) and juiciness (measured as cooking loss) – during chill ageing. The pH and temperature in longissimus thoracis muscle of 51 beef carcasses were recorded during 24 h post-mortem, and decay descriptors were then obtained by fitting exponential models. Measures of Warner-Bratzler shear force and cooking loss were obtained from cooked meat after 3, 8 and 13 days of cold ageing. The fitted mixed-effect models revealed that both meat tenderisation and cooking loss increased with ageing (P<0.01) although their rates slowed down in time (P<0.05). Beef carcasses with a higher pH (obtained at different endpoints: 1.5, 3.0, 4.5 or 6.0 h post-mortem) produced aged meat with increased tenderness (P=0.013) and increased water retention during cooking (P=0.016) than those of lower pH. Nonetheless, the slower the pH decay rate, as happens in a cold-shortened carcass, the lower the potential for tenderisation (P=0.038) and water retention (P=0.050) during ageing. Whereas sex affected shear force, with females producing meat of higher tenderness, aged meat of increased water retention was produced by heavier beef carcasses (P<0.001). The good fitting quality of the shear force (R2=0.847) and cooking loss (R2=0.882) models and their similarity among the different endpoints post-mortem indicated that both eating quality attributes can be approached by recording the pH decline of a beef carcass during the first 3.0 hours after slaughter.info:eu-repo/semantics/publishedVersio

A critical review of risk assessment models for listeria monocytogenes in dairy products

A review of the published quantitative risk assessment (QRA) models of L. monocytogenes in dairy products was undertaken in order to identify and appraise the relative effectiveness of control measures and intervention strategies implemented at primary production, processing, retail, and consumer practices. A systematic literature search retrieved 18 QRA models, most of them (9) investigated raw and pasteurized milk cheeses, with the majority covering long supply chains (4 farm-to-table and 3 processing-to-table scopes). On-farm contamination sources, either from shedding animals or from the broad environment, have been demonstrated by different QRA models to impact the risk of listeriosis, in particular for raw milk cheeses. Through scenarios and sensitivity analysis, QRA models demonstrated the importance of the modeled growth rate and lag phase duration and showed that the risk contribution of consumers’ practices is greater than in retail conditions. Storage temperature was proven to be more determinant of the final risk than storage time. Despite the pathogen’s known ability to reside in damp spots or niches, re-contamination and/or cross-contamination were modeled in only two QRA studies. Future QRA models in dairy products should entail the full farm-to-table scope, should represent cross-contamination and the use of novel technologies, and should estimate L. monocytogenes growth more accurately by means of better-informed kinetic parameters and realistic time–temperature trajectories.info:eu-repo/semantics/publishedVersio