Evaluation of microbial contamination of different pork carcass areas through culture-dependent and independent methods in small-scale slaughterhouses

Bacterial profile of pork from production to retail based on high-throughput sequencing

Pork is a common vehicle for foodborne pathogens, including Salmonella spp. and Yersinia enterocolitica. Cross-contamination can occur at any stage of the pork production chain, from farm to market. In the present study, high-throughput sequencing was used to characterize bacterial profiles and track their changes along the whole supply chain. Tracked meat samples (pig on the farm, carcass in the slaughterhouse, unprocessed carcass and processed meat in the processing plant, and fresh pork at the local retail stores) and their associated environmental samples (e.g., water, floor, feed, feces, and workers' gloves) were collected from sequential stages (n = 96) and subjected to 16S rRNA metataxonomic analyses. At the farm, a total of 652 genera and 146 exclusive genera were identified in animal and environmental samples (pig, drain, floor, fan, and feces). Based on beta diversity analysis, it was demonstrated that the microbial composition of animal samples collected at the same processing step is similar to that of environmental samples (e.g., drain, fan, feces, feed, floor, gloves, knives, tables, and water). All animal and environmental samples from the slaughterhouse were dominated by Acinetobacter (55.37 %). At the processing plant, belly meat and neck meat samples were dominated by Psychrobacter (55.49 %). At the retail level, key bacterial players, which are potential problematic bacteria and important members with a high relative abundance in the samples, included Acinetobacter (8.13 %), Pseudomonas (6.27 %), and Staphylococcus (2.13 %). In addition, the number of confirmed genera varied by more than twice that identified in the processing plant. Source tracking was performed to identify bacterial contamination routes in pork processing. Animal samples, including the processing plant's carcass, the pig from the farm, and the unwashed carcass from the slaughterhouse (77.45 %), along with the processing plant's gloves (5.71 %), were the primary bacterial sources in the final product. The present study provides in-depth knowledge about the bacterial players and contamination points within the pork production chain. Effective control measures are needed to control pathogens and major pollutants at each stage of pork production to improve food safety.

Beef carcass microbiota after slaughtering and primary cooling: A metataxonomic assessment to infer contamination drivers

The impact of primary cooling on beef microbiota was investigated on six beef carcasses consecutively processed with the parallel use of metataxonomic and culture-dependent analysis. Samples were collected immediately after slaughtering (AS) and after the 24th-hour post-cooling (PC) from three different surfaces, namely neck, flank and thigh. The main objective was to examine whether the microbiota composition of beef carcasses changes as function of the surface sampled, primary cooling (from AS to PC) and animal's origin (breeder). The outcomes underline that primary cooling did not affect qualitatively the composition of the potentially active microbiota or the carcass superficial counts. Although slight changes in chemical-physical parameters like volatile organic compounds (VOCs) were observed after cooling, the carcasses microbiota and its inferred metabolic pathways varied among animals as a function of their origin. Co-occurrence and co-exclusion analyses underlined competition for the colonisation of the carcass surface between Brochothrix-Psychrobacter and Carnobacterium-Serratia-Pseudomonas. Once integrated in a comprehensive monitoring of the supply chain, the metataxonomic characterisation of the beef carcasses microbiota might represent a valid integrative approach to define the cuts' perishability and their appropriateness to specific packaging and storage methods. These new bits of knowledge could be the base to define good strategies for the prevention of meat spoilage.

Assessment of ATP-Bioluminescence and Dipslide Sampling to Determine the Efficacy of Slaughterhouse Cleaning and Disinfection Compared with Total Aerobic and Enterobacterales Counts

Inadequate cleaning and disinfection (C&D) in slaughterhouses can cause bacterial contamination of meat, resulting in foodborne disease and reduced meat quality. Different methods for monitoring the efficacy of C&D procedures are available, but few studies have assessed their reliability. This study examined C&D efficacy in slaughterhouses and evaluated the diagnostic performance of methods for measuring surface hygiene. One red meat and one poultry slaughterhouse in Sweden were each visited on six occasions before and six occasions after C&D. Sampling points were sampled with: swabbing and plating for total aerobic bacteria (TAB) and Enterobacterales (EB); dipslides for total viable count; and ATP-bioluminescence tests. To evaluate the diagnostic performance of the dipslide and ATP-bioluminescence methods, the results were compared with (TAB) as a reference. In total, 626 samples were collected. For the majority of samples, TAB was lower after than before C&D and EB were mainly detected before C&D, indicating C&D efficacy. Greater reductions in mean TAB were observed in processing areas (2.2 and 2.8 log CFU/100 cm2 in red meat and poultry slaughterhouse, respectively) than in slaughter areas (1.3 log CFU/100 cm2 in both slaughterhouses). Approximately half of all samples were assessed as non acceptably clean (52% for red meat and 46% for poultry slaughterhouse) according to previously published thresholds. Critical food contact surfaces that were insufficiently cleaned and disinfected were plucking fingers, shackles, and a post-dehairing table. Cleaning and disinfection of drains and floors were inadequate. The ATP-bioluminescence method showed low specificity compared with the reference (TAB) in both the red meat (0.30) and poultry slaughterhouses (0.64). The sensitivity of dipslides was low (0.26) in the red meat slaughterhouse compared with TAB. A combination of ATP-bioluminescence and dipslides could provide more accurate estimates of C&D efficacy.

Microbiological and chemical analysis of food collected under official control in the Emilia-Romagna region of northern Italy, 2014-2019

This study analyzed data from six years (2014-2019) of official controls in the Emilia-Romagna region (northern Italy) to investigate the frequencies of human pathogens and chemical hazards in foods during production and distribution. Campylobacter spp. was the most prevalent pathogen, isolated in 4.4% of the 1,078 food samples examined, followed by Salmonella spp. (2.8%), Shiga toxin-producing Escherichia coli (STEC) (1.9%) and Listeria monocytogenes (0.9%). Salmonella serotyping showed that the isolates belonged to the serotypes most commonly isolated from humans in Emilia-Romagna. These serotypes were: S. Infantis (34.8%), mostly isolated from chicken, monophasic S. Typhimurium (1,4, (Anonymous, 2013),12:i:-) (12.6%), S. Bredeney (8.9%) and S. Derby (8.6%). No Clostridium botulinum, Yersinia spp. and Shigella spp. were isolated. No positivity was detected for hepatitis A virus, while 5.1% samples taken in the production phase of the food chain were found to be contaminated with norovirus. The chemical analyses identified environmental contaminants within legal limits (heavy metals, 0.6% positive overall; mycotoxins, 0.4% positive overall), analytes subjected to monitoring (perfluoro-alkyl substances (PFASs), 6.2% positive overall; inorganic arsenic, no positives overall) and process contaminants and additives within legal limits (acrylamide, 9.6% positive overall; permitted or non-permitted additives, 0.9% positive overall). Only one sample showed dioxins and polychlorinated biphenyls (PCBs) at levels higher than the legal limits. The monitoring by competent authorities (CA) of food contamination can generate useful data that can be used as a basis for estimating the exposure to different food contaminants over time and for evaluating the effects of control measures on the contamination of food.

Role of Feeding and Novel Ripening System to Enhance the Quality and Production Sustainability of Curd Buffalo Cheeses

The buffalo dairy sector is extending its boundaries to include new buffalo cheese productions beyond mozzarella, overcoming some barriers that make cheeses expensive and unsustainable. This study aimed to evaluate the effects of both the inclusion of green feed in the diet of Italian Mediterranean buffaloes and an innovative ripening system on buffalo cheese quality, providing solutions capable of guaranteeing the production of nutritionally competitive and sustainable products. For this purpose, chemical, rheological, and microbiological analyses were carried out on cheeses. Buffaloes were fed with or without the inclusion of green forage. Their milk was used to produce dry ricotta and semi-hard cheeses, ripened according to both respective traditional (MT) and innovative methods (MI); these are based on automatic adjustments of climatic recipe guided by the continuous control of pH. Green feed enhances the nutritional profile of the final products (high content of MUFAs and PUFAs). As far as the ripening method is concerned, to our knowledge, this is the first study that tests aging chambers, commonly used for meat, for the maturing of buffalo cheeses. Results pointed out the MI validity also in this field of application, as it shortens the ripening period without negatively compromising any of desirable physicochemical properties and the safety and hygiene of the final products. Conclusively, this research highlights the benefits of diets rich in green forage on productions and provides support for the ripening optimization of buffalo semi-hard cheeses.

Pearls before Swine: Plant-Derived Wastes to Produce Low-Cholesterol Meat from Farmed Pigs-A Bibliometric Analysis Combined to Meta-Analytic Studies

Due to environmental and human factors, there is a growing amount of agri-food waste worldwide. The European Commission is incentivizing a zero-waste policy by 2025, pushing to find a "second life" for at least the avoidable ones. In this review, after summarizing the nutritional values of pork and the importance of its inclusion in human diet, a phylogenetic analysis was conducted to investigate potential differences in the structure and activity of HMGCR, which is a key enzyme in cholesterol metabolism. In addition, a bibliometric analysis combined with visual and meta-analytical studies on 1047 scientific articles was conducted to understand whether the inclusion of agro-food waste could affect the growth performance of pigs and reduce cholesterol levels in pork. Although some critical issues were highlighted, the overall data suggest a modern and positive interest in the reuse of agri-food waste as swine feed. However, although interesting and promising results have been reported in several experimental trials, further investigation is needed, since animal health and meat quality are often given marginal consideration.

Occurrence and distribution of Salmonella serovars in carcasses and foods in southern Italy: Eleven-year monitoring (2011–2021)

Salmonella is one of the most common agents of foodborne illness. The genus Salmonella includes two species (Salmonella bongori and S. enterica) and six subspecies (enterica I, salamae II, arizonae IIIa, diarizonae IIIb, houtenae IV, and indica VI), each of which contains multiple serotypes associated with animal and human infections. The aim of the study was to evaluate the presence of Salmonella spp. in carcasses of food-producing animals and foods in southern Italy and the serovar distribution among different sources. From 2011 to 2021, a total of 12,246 foods and 982 samples from animal carcasses were collected and analyzed. The overall percentage of positive samples was 5.84% (N = 773) and a significant increase in prevalence was observed by comparing the years 2011–2015 (257, 3.27%) and 2016–2021 (516, 9.61%; p < 0.05). The highest percentage of positive food samples was observed in “Meat and Meat Products” (N = 327/2,438, 13.41%) followed by “Fish and fishery products” (N = 115/1,915, 6.01%). In carcasses, the highest percentage of positive samples was reported from broilers (N = 42/81, 51.85%) followed by buffalo (N = 50/101, 49.50%) and pork (N = 140/380, 36.84%). After typing, the isolates were assigned to the species S. enterica and to the subspecies: enterica (N = 760, 98.32%), diarizonae (N = 8, 1.03%), salamae (N = 3, 0.39%) and houtenae (N = 2, 0.26%). S. Infantis was the most frequently detected (N = 177, 24.76%), followed by S. Derby (N = 77, 10.77%), monophasic S. Typhimurium (N = 63, 8.81%), S. Typhimurium (N = 54, 7.55%), and S. Rissen (N = 47, 6.57%). By comparing the sampling period 2011–2015 with that of 2016–2021, an increase in the prevalence of S. Infantis and monophasic S. Typhimurium and a decrease of S. Typhimurium were recorded (p < 0.05). Thus, present data suggest that, despite the implementation of national and European control strategies to protect against Salmonella, the prevalence of this pathogen in southern Italy is still increasing and a change of national control programs to protect against Salmonella are necessary.

Microbiological Safety and Shelf-Life of Low-Salt Meat Products—A Review

Salt is widely employed in different foods, especially in meat products, due to its very diverse and extended functionality. However, the high intake of sodium chloride in human diet has been under consideration for the last years, because it is related to serious health problems. The meat-processing industry and research institutions are evaluating different strategies to overcome the elevated salt concentrations in products without a quality reduction. Several properties could be directly or indirectly affected by a sodium chloride decrease. Among them, microbial stability could be shifted towards pathogen growth, posing a serious public health threat. Nonetheless, the majority of the literature available focuses attention on the sensorial and technological challenges that salt reduction implies. Thereafter, the need to discuss the consequences for shelf-life and microbial safety should be considered. Hence, this review aims to merge all the available knowledge regarding salt reduction in meat products, providing an assessment on how to obtain low salt products that are sensorily accepted by the consumer, technologically feasible from the perspective of the industry, and, in particular, safe with respect to microbial stability.

Similar Carcass Surface Microbiota Observed Following Primary Processing of Different Pig Batches

Bacterial contamination during meat processing is a concern for both food safety and for the shelf life of pork meat products. The gut microbiota of meat-producing animals is one of the most important sources of surface contamination of processed carcasses. This microbiota is recognized to vary between pigs from different farms and could thus be reflected on the bacterial contamination of carcasses at time of processing. In this study, the microbiota of 26 carcasses of pigs originating from different farms (i.e., batches) were compared to determine if an association could be observed between carcass surface microbiota (top and bottom) and the origin of slaughtered animals. The microbiota of the top and bottom carcass surface areas was analyzed by culturing classical indicator microorganisms (mesophilic aerobic bacteria, Enterobacteria, Escherichia coli, Pseudomonas, and lactic bacteria), by the detection of Salmonella, and by 16S rRNA gene sequencing. Culture results showed higher Enterobacteria, E. coli, and lactic bacteria counts for the bottom areas of the carcasses (neck/chest/shoulder) when compared to the top areas. Salmonella was not detected in any samples. Globally, 16S rRNA gene sequencing showed a similar composition and diversity between the top and bottom carcass areas. Despite the presence of some genera associated with fecal contamination such as Terrisporobacter, Escherichia-Shigella, Turicibacter, Clostridium sensustricto1, and Streptococcus on the carcass surface, sequencing analysis suggested that there was no difference between the different batches of samples from the top and bottom areas of the carcasses. The primary processing therefore appears to cause a uniformization of the carcass global surface microbiota, with some specific bacteria being different depending on the carcass area sampled.

A risk assessment model for Salmonella spp. in swine carcasses

Salmonellosis is one of the most important food‐borne outbreaks that occurs in the EU/EEA. From the first production stages at slaughter, meat is susceptible to spoilage and can be a substrate for the pathogenic microorganisms growth. Among the pathogens, the presence of Salmonella is mainly due to mishandling during the evisceration stage. For the year 2019, according to the collected data from MSs, on the 17.9% of all food‐borne outbursts, the presence Salmonella was confirmed. Pork meat is considered as one of the four most commonly reported foods in cases of salmonellosis. For the training purposes of this project, Salmonella isolation and identification along with RA for carcass contamination, was performed. Pig carcasses were sampled using the non‐destructive technique. The sampling took place post dressing and before the stage of chilling. For the Salmonella detection, a three phases process was performed (pre‐enrichment, enrichment, isolation). A total of 757 samples were collected, 19 were found to be positive for Salmonella. The most common was found to be Salmonella Derby, which was identified eight times. The main objective of the project was to determine the prevalence of Salmonella spp. in swine carcasses. Moreover, certain parameters were evaluated in terms of their influence on the prevalence of Salmonella. A stochastic simulation model was developed in Microsoft Office Excel 2019 by using the add‐in @Risk v.8.1. The prevalence was estimated to be 2.6%. For the pigs sampled, the average value of the distance from farm to slaughterhouse was 200.92 km. Additionally, the average weight of the carcasses was 127.97 kg. The prevalence of Salmonella between the samples that came from farms with a distance above the average, was higher by 1.7 units, while the prevalence for the samples with weight above the average was higher by 0.2 units. According to the stochastic model, it is specified that the prevalence is higher with greater distance, and there is an 8.1% probability the prevalence will exceed the legislation’s – hygiene criteria. In addition, the prevalence of Salmonella was shown to increase, as well in the case of samples from weightier animals, but to a lesser extent.

Consumers' Perception and Preference for the Consumption of Wild Game Meat among Adults in Poland

Wild game meat can be a healthier, safer, and more environmentally friendly alternative to meat from farm animals. The aims of this study were to know the preferences and opinions of Polish consumers regarding game meat and its use in their diet, and to identify consumer segments based on differences in individual game meat choices, concerns, and eating habits related to game meat. The survey was conducted using the platform for online surveys among 1261 adult Poles. Six clusters characterizing the behavior of game consumers were identified (casual consumers, occasional game gourmets, indifferent consumers, occasional consumers, accidental consumers, wild game lovers) and four clusters among those who do not eat game (uninterested, restricted, dislikers, fearful). It has been found that wild game is more often eaten by hunters and their family or friends. The most common reasons for not consuming game are high prices, low availability, no family tradition, and unacceptable taste. Many positive respondents eat game because of its nutritional value but are concerned about the potential health risks and lack of cooking skills. The results of this study indicate the need for information programs for consumers about this meat. They will provide guidance to meat companies about consumer preferences for game and allow them to develop appropriate marketing strategies.

Analysis of microbiota structure in cooked ham as influenced by chemical composition and processing treatments: Identification of spoilage bacteria and elucidation on contamination route

Spoilage in cooked ham is one of the main challenges where microbial contamination can play a fundamental role. This study aimed to characterize pork-cooked ham's microbial community changes among different food production conditions (formulation and processing) using 16S rRNA sequencing and also to investigate the spoilage bacteria in order to elucidate their contamination route. Samples of three pork-cooked ham references with and without post-pasteurization treatment and in contact with the slicing-packaging conveyor belt and slicer and packager surfaces were performed by 16S rRNA gene sequencing. In order to clarify the contamination route, surfaces were sampled by conventional microbiological methods. Results showed that Leuconostoc spp. was the principal genera in spoiled cooked ham and had no relation neither to formulation nor contact with the slicing-packaging conveyor belt. The contamination route found for Leuconostoc spp. was associated with the storage and packaging zone. In addition, the calculated shelf-life decreased to 57.5% independently of the environment interaction minimization when ham casing permeability was changed and linked to contamination of spoilage bacteria during the slicing and packaging process. This research illustrates how the combined approach provides complementary results to implement suggestions in the facility to reduce the cross-contamination with spoilage bacteria. It also generates tools to comprehend and propose transference models understanding the environmental and intrinsic factors related to microbial transfer rate.

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The structure of the bacterial community in cooked ham had no relation to the formulation.

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Genus Leuconostoc dominated the spoilage in cooked ham.

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The methodology allows validating the contamination route for spoilage bacteria.

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Post-pasteurization treatment reduce microbiota diversity.

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The ham shelf lifetime decrease get related to cross-contamination during slicing.