Mycobiota and mycotoxins in Portuguese pork, goat and sheep dry-cured hams

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.

Regional distribution and diversity of Aspergillus and Penicillium species on Croatian traditional meat products

Various factors, such as weather and production practices (e.g., environmental hygiene, process duration, raw material quality, ripening temperature, and relative humidity), in combination with the intrinsic product properties (e.g., pH, aw, salt content), significantly affect the growth of surface moulds. The aim of this study was to isolate and identify surface moulds retrieved from traditional meat products (TMPs) and correlate these data to the production region and production technology. The surface of 250 TMPs (dry-fermented sausages, n = 108; dry-cured meat products, n = 142) from five Croatian regions were sampled during a two-year period. Dry-fermented sausages had a significantly higher pH and a lower salt concentration when compared to dry-cured meat products. In total, 528 isolates were obtained, comprising 20 Penicillium and 17 Aspergillus species. The species most frequently isolated from the dry-fermented sausages were P. commune (32.4 %), A. proliferans (33 %), and P. solitum (14.8 %), while A. proliferans (52.1 %), P. commune (28.9 %) and P. citrinum (19.7 %) predominated in dry-cured meat products. Aspergillus predominated on the TMPs from southern Croatia, while Penicillium was prevalent on products from the other four regions, possibly due to differences in weather conditions. Seven potentially mycotoxigenic species (A. creber, A. flavus, A. niger, A. westerdijkiae, P. citrinum, P. commune, and P. nordicum) were isolated and identified. Regular monitoring of mould species and their toxigenic metabolites present on traditional meat products is of the utmost importance from the public health perspective, while the results of such a monitoring can prove beneficial for the tailoring of the production technology development.

Deciphering Staphylococcus xylosus and Staphylococcus equorum mode of action against Penicillium nordicum in a dry-cured ham model system

Penicillium nordicum is one of the major producers of ochratoxin A (OTA) in dry-cured ham. Staphylococcus xylosus Sx8 and Staphylococcus equorum Se31 have been previously proposed as biocontrol agents (BCAs) to prevent the OTA contamination, although their antifungal mode of action has not been established yet. Thus, the aim of this work was to elucidate their mode of action against P. nordicum in a dry-cured ham model system. For this, the effect of live cells, dead cells, and cell-free broth; the nutritional utilisation pattern, niche overlap index (NOI), interactions by dual-culture assays, antifungal effect of volatile compounds, OTA detoxification, and effect on fungal proteome were determined. No fungal growth was observed after 14 days of co-culture with live cells of each staphylococcus at 15 or 20 °C. However, such inhibition was not observed with either dead cells or extracellular extracts. The number of carbon sources utilised by P. nordicum was higher than those used by both cocci at 20 °C, whilst the opposite occurred at 15 °C. According to NOI, nutritional dominance depends on temperature, at 20 °C P. nordicum dominated the niche, but at 15 °C the mould is dominated by the BCAs. The volatile pattern generated by each coccus did not show antifungal effect, and both staphylococci failed to degrade or adsorb OTA. However, in the interaction assay, S. xylosus and S. equorum were able to decrease the fungal growth and its OTA production. In addition, proteomic analyses showed changes in the abundance of proteins related to the cell wall integrity (CWI), carbohydrate metabolism and the biosynthesis of secondary metabolites such as OTA. In conclusion, overall, the antagonistic effects of the two studied cocci against P. nordicum are greater at 15 °C than at 20 °C, being linked to competition for space and nutrients, triggering alterations in CWI pathway, OTA biosynthesis, and carbohydrate metabolism.

Ochratoxin A in Dry-Cured Ham: OTA-Producing Fungi, Prevalence, Detection Methods, and Biocontrol Strategies-A Review

Traditional dry-cured hams are easily contaminated by toxigenic fungi during the fermentation and ripening stages. The detection and positive rates of ochratoxin A (OTA) are the highest among mycotoxins detected in traditional dry-cured hams, indicating that OTA in hams is a potential safety hazard to human health. This review addresses the mycotoxin-producing fungal species, the toxigenic conditions causing OTA contamination worldwide, the prevalence of OTA contamination in dry-cured hams, and the detection methods applied in OTA analysis. Additionally, this study introduces methods to prevent and control OTA in traditional dry-cured hams. The growth of common mycotoxin-producing fungi and the accumulation of mycotoxins in dry-cured ham can be controlled by a microbial starter. This review provides an important theoretical foundation for the research and control of OTA in traditional dry-cured hams.

Underreported Human Exposure to Mycotoxins: The Case of South Africa

South Africa (SA) is a leading exporter of maize in Africa. The commercial maize farming sector contributes to about 85% of the overall maize produced. More than 33% of South Africa’s population live in rural settlements, and their livelihoods depend entirely on subsistence farming. The subsistence farming system promotes fungal growth and mycotoxin production. This review aims to investigate the exposure levels of the rural population of South Africa to dietary mycotoxins contrary to several reports issued concerning the safety of South African maize. A systematic search was conducted using Google Scholar. Maize is a staple food in South Africa and consumption rates in rural and urban communities are different, for instance, intake may be 1–2 kg/person/day and 400 g/person/day, respectively. Commercial and subsistence maize farming techniques are different. There exist differences influencing the composition of mycotoxins in food commodities from both sectors. Depending on the levels of contamination, dietary exposure of South Africans to mycotoxins is evident in the high levels of fumonisins (FBs) that have been detected in SA home-grown maize. Other potential sources of exposure to mycotoxins, such as carryover effects from animal products and processed foods, were reviewed. The combined effects between FBs and aflatoxins (AFs) have been reported in humans/animals and should not be ignored, as sporadic breakouts of aflatoxicosis have been reported in South Africa. These reports are not a true representation of the entire country as reports from the subsistence-farming rural communities show high incidence of maize contaminated with both AFs and FBs. While commercial farmers and exporters have all the resources needed to perform laboratory analyses of maize products, the greater challenge in combatting mycotoxin exposure is encountered in rural communities with predominantly subsistence farming systems, where conventional food surveillance is lacking.

Ochratoxin A in Slaughtered Pigs and Pork Products

Ochratoxin A (OTA) is a mycotoxin that is produced after the growth of several Aspergillus and Penicillium spp. in feeds or foods. OTA has been proved to possess nephrotoxic, hepatotoxic, teratogenic, neurotoxic, genotoxic, carcinogenic and immunotoxic effects in animals and humans. OTA has been classified as possibly carcinogenic to humans (Group 2B) by the IARC in 2016. OTA can be mainly found in animals as a result of indirect transmission from naturally contaminated feed. OTA found in feed can also contaminate pigs and produced pork products. Additionally, the presence of OTA in pork meat products could be derived from the direct growth of OTA-producing fungi or the addition of contaminated materials such as contaminated spices. Studies accomplished in various countries have revealed that pork meat and pork meat products are important sources of chronic dietary exposure to OTA in humans. Various levels of OTA have been found in pork meat from slaughtered pigs in many countries, while OTA levels were particularly high in the blood serum and kidneys of pigs. Pork products made from pig blood or organs such as the kidney or liver have been often found to becontaminated with OTA. The European Union (EU) has established maximum levels (ML) for OTA in a variety of foods since 2006, but not for meat or pork products. However, the establishement of an ML for OTA in pork meat and meat by-products is necessary to protect human health.

The Influence of Surface Mycobiota on Sensory Properties of “Istarski pršut” and “Dalmatinski pršut”

This study aimed to identify surface mould species overgrowing the Croatian protected meat products “Istarski pršut” and “Dalmatinski pršut” and their effect on sensory properties. Dry-cured hams were produced in 2018/2019 and obtained from annual fairs. The predominant surface species found on “Dalmatinski pršut” were Aspergillus chevalieri, Penicillium citrinum and Aspergillus cibarius, whereas those overgrowing “Istarski pršut” were Aspergillus proliferans, P. citrinum and Penicillium salamii. The results show species diversity, higher presence, and greater variety of Aspergillus species in “Dalmatinski pršut” in comparison to “Istarski pršut”, and significant variations in 9 of 20 sensory attributes. Principal component analysis revealed a clear distinction between the two, and a large contribution of P. salamii and Penicillium bialowienzense to one principal component. The texture traits, smoky odour, muscle and subcutaneous fatty tissue colour, and mould species found are valuable for product characterisation. The results also indicate that mould species may be responsible for some sensory traits, such as tenderness, juiciness, and lesser freshness.

Multi-mycotoxin occurrence in feed, metabolism and carry-over to animal-derived food products: A review

The world requests for raw materials used in animal feed has been steadily rising in the last years driven by higher demands for livestock production. Mycotoxins are frequent toxic metabolites present in these raw materials. The exposure of farm animals to mycotoxins could result in undesirable residues in animal-derived food products. Thus, the potential ingestion of edible animal products (milk, meat and fish) contaminated with mycotoxins constitutes a public health concern, since they enter the food chain and may cause adverse effects upon human health. The present review summarizes the state-of-the-art on the occurrence of mycotoxins in feed, their metabolism and carry-over into animal source foodstuffs, focusing particularly on the last decade. Maximum levels (MLs) for various mycotoxins have been established for a number of raw feed materials and animal food products. Such values are sometimes exceeded, however. Aflatoxins (AFs), fumonisins (FBs), ochratoxin A (OTA), trichothecenes (TCs) and zearalenone (ZEN) are the most prevalent mycotoxins in animal feed, with aflatoxin M₁ (AFM1) predominating in milk and dairy products, and OTA in meat by-products. The co-occurrence of mycotoxins in feed raw materials tends to be the rule rather than the exception, and the carry-over of mycotoxins from feed to animal source foods is more than proven.

Tissue Type: A Crucial Factor Influencing the Fungal Diversity and Communities in Sichuan Pork Bacon

This study aimed to the variations of fungal diversity and community structure in different parts of traditional homemade Sichuan pork bacon. A total of seven phyla and 91 fungal genera were identified. Among them, Ascomycota and Basidiomycota were the first and second most abundant phyla in the bacon tissues. In addition, five dominant genera (Aspergillus, Candida, Debaryomyces, Malassezia, and Penicillium) were shared by all bacon tissues. The numbers of OTUs unique to individual groups were 14, 67, and 65 for the muscle tissue, the adipose tissue, and pork skin, respectively. Linear discriminant analysis showed that a total of 31 taxa significantly differed among the groups. Results of redundancy analysis indicated that fat content, protein content, aw, and pH of bacon tissue shaped the bacon fungal communities. Results of network analysis also indicated that tissue type was a crucial factor influencing the fungal interactions in different tissues. This study can lay a foundation for further isolation and identification of fungi in the product and provides a basis for further research of food health in homemade traditional pork bacon.

Mycotoxins-Biomonitoring and Human Exposure

Mycotoxins are secondary metabolites produced by fungal species that commonly have a toxic effect on human and animal health. Different foodstuff can be contaminated and are considered the major source of human exposure to mycotoxins, but occupational and environmental exposure can also significantly contribute to this problem. This review aims to provide a short overview of the occurrence of toxigenic fungi and regulated mycotoxins in foods and workplaces, following the current literature and data presented in scientific papers. Biomonitoring of mycotoxins in plasma, serum, urine, and blood samples has become a common method for determining the exposure to different mycotoxins. Novel techniques are more and more precise and accurate and are aiming toward the simultaneous determination of multiple mycotoxins in one analysis. Application of liquid chromatography (LC) methodologies, coupled with tandem mass spectrometry (MS/MS) or high-resolution mass spectrometry (HRMS) has become a common and most reliable method for determining the exposure to mycotoxins. Numerous references confirm the importance of mycotoxin biomonitoring to assess the exposure for humans and animals. The objectives of this paper were to review the general approaches to biomonitoring of different mycotoxins and the occurrence of toxigenic fungi and their mycotoxins, using recent literature sources.

Sheep and Goat Meat Processed Products Quality: A Review

Even though sheep and goat processed meat products are not as popular as pork, beef or poultry and are generally considered not as important, they have a very important role in meat consumption around the world. A concise review of the origin and type of the most important sheep and goat processed meat products produced in different countries and world regions is made. The manuscript also summarizes the most recent studies on sheep and goat processed meats on the physicochemical characterizations, sensory quality, microbiological quality and safety. Some conclusions and future trends in production, processing and commercial potentiality for sheep and goat processed meat products are discussed. Several possibilities exist to make them more diversified and appealing to the market. Processing meat from culled animals is an interesting way to value animals with low market acceptability. Some as fermented sausages, cured legs and pâtés have great commercial potential as highly acceptable consumer commodities. An interesting field of food research is the rediscovery of a new generation of goat and sheep meat products as functional foods that will respond to the constant innovation required by the meat industry. Everything related to food safety must be considered in the future.