Presence of ochratoxin A on the surface of dry-cured Iberian ham after initial fungal growth in the drying stage

Investigation of ochratoxin A in air-dry-cured hams

The European Union legislation regarding ochratoxin A (OTA) in various foodstuffs has changed relatively recently. Nevertheless, the legislation does not regulate OTA in any meat and meat-derived products. In this legislation update, the European Commission requested new studies, including, besides others, the presence of OTA in hams, which raises the concern that its consumption may pose a potential risk of exposure to OTA. This study aims to investigate OTA in a total of 195 samples of air-dry-cured hams acquired at the Czech market from January to June 2023. The analytical technique of high-performance liquid chromatography in combination with a fluorescence detector with pre-treatment employing immunoaffinity columns was used to determine OTA. OTA was found in 93 (48%) samples of air-dry-cured ham, with the OTA concentration reaching up to 14.58 ng/g. Due to the current absence of regulation limits, the results of this study were compared with the Italian maximum limit of 1 ng/g regulating OTA in porcine meat and byproducts. The Italian OTA maximum limit was exceeded in 22 (11%) samples. This study shows that the population of the Czech Republic is exposed to OTA from this pork byproduct. It is essential to set an OTA regulatory limit for meat and food produced from it to protect human health.

Meat Starter Culture Reduces Aspergillus parasiticus Production of Aflatoxins on Meat-Based and Salami Model Media

There is great concern about the risk posed by the consumption of food contaminated with aflatoxins (AF), produced mostly by Aspergillus strains, that can also be found in dry-fermented meat products (DFMPs). The aim of this study was to investigate the inhibitory effect of meat starter culture (SC), frequently used for fermentation in the meat industry, on A. parasiticus growth and the production of aflatoxin B1 (AFB1), aflatoxin B2 (AFB2), aflatoxin G1 (AFG1), aflatoxin G2 (AFG2), and sterigmatocystin (STE) on different meat-based (CMA) and salami model (SM-G) media. Incubation was carried out under optimal conditions for fungal growth and under typical conditions for ripening of DFMPs for 21 days. Reversed-phase UPLC-MS/MS analysis was performed to determine mycotoxin production. SC reduced A. parasiticus growth more on CMA than on SM-G media. AFB1 formation was inhibited on both types of SC-containing media, although SC generally had a stronger inhibitory effect on AFB1 production on CMA than on SM-G. AFB1 and AFB2 were produced on CMA, while AFB1 dominated in SM-G, AFG1, and AFG2 were not detected in any media. The results show that SC inhibited AFB1 formation of A. parasiticus on SM-G media after 21 days of incubation under typical conditions for the production of DFMPs. These results indicate the necessity to investigate AF on natural matrices in an environment that is as similar as possible to real conditions in the production of DFMPs.

Role of microbiota and its ecological succession on flavor formation in traditional dry-cured ham: a review

Traditional dry cured ham (DCH) is favored by consumers for its distinctive flavor, derived from an array of volatile organic compounds (VOCs). Microbiota play a pivotal role in the formation of VOCs. To fully comprehend the pathway by which the microbiota enhance the flavor quality of DCH, it is imperative to elucidate the flavor profile of DCH, the structural and metabolic activities of the microbiota, and the intricate relationship between microbial and VOCs. Thus far, the impact of microbiota on the flavor profile of DCH has not been comprehensively discussed or reviewed, and the succession of bacteria, especially at distinct phases of processing, has not been adequately summarized. This article aims to encapsulate the considerable potential of ferments in shaping the flavor characteristics of DCH, while elucidating the underlying mechanisms through which VOCs are generated in hams via microbial metabolism. Throughout the various stages of DCH processing, the composition of microbiota undergoes dynamic changes. Furthermore, they directly participate in the formation of VOCs in DCH through the catabolism of amino acids, metabolism of fatty acids, and the breakdown of carbohydrates. Several microorganisms, including Lactobacillus, Penicillium, Debaryomyces, Pediococcus, and Staphylococcus, exhibit considerable potential as fermenters in ham production.

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.

Traditional Meat Products-A Mycotoxicological Review

Traditional meat products are commonly produced in small family businesses. However, big industries are also involved in the production of this kind of product, especially since a growing number of consumers crave the traditional taste and aromas. The popularization of original and organic products has resulted in a return to traditional production methods. Traditional meat products are produced worldwide. However, in such (domesticated) conditions there is a potential danger for mycotoxin contamination. This review aims to present the sources of mycotoxins in traditional meat products, the most common mycotoxins related to such meat products, and future prospects regarding the suppression of their occurrence. Special attention should be paid to reducing the transfer of mycotoxins via the food chain from animal feed to animals to humans (stable-to-table principle), which is also described in this review. Other sources of mycotoxins (spices, environment, etc.) should also be monitored for mycotoxins in traditional production. The importance of monitoring and regulating mycotoxins in meat products, especially in traditional meat products, is slowly being recognized by the institutions and hopefully, in the future, can deliver legally regulated limits for such products. This is especially important since meat products are available to the general population and can seriously affect human health.

Spontaneously growing fungi on the surface and processing areas of matured sheep ham and volatile compounds produced

Raw ham is a dried and matured product traditionally made from pork leg, but other animals, such as sheep, can be used. The natural presence of bacteria and fungi in this product influences its characteristics throughout the process. This study analysed the fungal populations present during raw sheep hams' processing. Two types of products were developed: without and with the addition of seasonings. Mycological analyses were carried out from the ingredients, seasonings, facilities air, as well as on the surfaces of the hams and the air in the chamber throughout the maturation period (0, 45, 90, and 180 days) using 18 % dichloran glycerol agar and the data were submitted to Principal Component Analysis. Volatile compounds were evaluated at the end of the sheep ham manufacturing process through a gas chromatograph coupled to a mass spectrometer. At 45 days of aging, a more remarkable similarity was observed between the fungi present on the non-seasoned hams and those in the ripening chamber's air, while the seasoned hams showed a more evident relation with those fungi present in the spices. With time, the fungi in the air of the ripening chamber started to be influenced by Aspergillus ser. Aspergillus and Aspergillus ser. Rubri already installed in the seasoned hams at 45 days, and then it probably dispersed the non-seasoned ones due to the airborne spores, becoming the most prevalent in both treatments at 90 days. At the end of ripening, the mycobiota of both raw hams was composed mainly by xerophilic species of Aspergillus section Aspergillus. The total fungal count was 5.78 log CFU/cm2 for the non-seasoned and 7.19 log CFU/cm2 for the seasoned ones. A potentially ochratoxigenic Aspergillus ser. Circumdati was detected at the end of aging in raw, unseasoned hams. In conclusion, seasoning directly influences the species developing on the surface of seasoned hams throughout the ripening process, and indirectly affects the mycobiota of the non-seasoned hams when sharing the same ripening chamber. The presence of fungi in the matured sheep ham seems to contribute to the formation of volatile compounds, which are related to the sensory quality of these products.

The prevalence and concentration of ochratoxin A in meat and edible offal: A global systematic review and meta-analysis

The prevalence of ochratoxin A (OTA) in meat, edible offal, and meat products (MOP) was assessed through systematic review and meta-analysis. Four electronic databases were used to gather data from 1975 to September 15, 2022. Seventy-five articles comprising 8585 samples were identified and analyzed. The studies included in the analysis were conducted at a global level, with a predominant focus on Europe [72% (54/75)], Asia [13.33% (10/75)], Africa [13.33% (10/75)], and North America [1.33% (1/75)]. The overall prevalence of OTA in MOP was 39%. The highest and lowest prevalence percentages were recorded in Iraq (77%) and the USA (3%), respectively. Concerning food type, OTA prevalence was highest in the poultry gizzard (66%) and lowest in the cow liver (2%). The overall concentration of OTA in the MOP was 1.789 μg/kg. Poultry kidneys had the highest concentration of OTA (0.880-22.984 μg/kg), while pork had the lowest concentration (0.127-0.824 μg/kg). Conspicuous amounts of OTA contamination have been reported in fermented sausages. The lowest OTA concentration was found in Belgium (0.220 μg/kg) and the highest in Denmark (60.527μg/kg). These results can help food authorities minimize and control OTA in the MOP.

Factors That Interfere in the Action of Sanitizers against Ochratoxigenic Fungi Deteriorating Dry-Cured Meat Products

This study verified the factors affecting the antifungal efficacy of sanitizers against ochratoxin A-producing fungi. The fungi Penicillium nordicum, Penicillium verrucosum, and Aspergillus westerdijkiae were exposed to three sanitizers at three concentrations: peracetic acid (0.3, 0.6, 1%), benzalkonium chloride (0.3, 1.2, 2%), and sodium hypochlorite (0.5, 0.75, 1%) at three exposure times (10, 15, and 20 min), three temperatures (10, 25, and 40 °C), and with the presence of organic matter simulating clean (0.3%) and dirty (3%) environments. All the tested conditions influenced the antifungal action of the tested sanitizers. Peracetic acid and benzalkonium chloride were the most effective sanitizers, and sodium hypochlorite was ineffective according to the parameters evaluated. The amount of organic matter reduced the antifungal ability of all sanitizers. The longer exposure time was more effective for inactivating fungi. The temperature acted differently for benzalkonium chloride, which tended to be favored at low temperatures, than for sodium hypochlorite and peracetic acid, which were more effective at higher temperatures. The knowledge of the parameters that influence the action of sanitizers on spoilage fungi is vital in decision-making related to sanitizing processes in the food industry.

Impact of environmental factors on ochratoxin A: From natural occurrence to control strategy

Ochratoxin A (OTA) contamination and the associated issues of food security, food safety and economic loss are widespread throughout the world. The occurrence of OTA depends on ochratoxigenic fungi, foodstuffs and their environment. In this review, natural occurrence and control strategy of OTA, with a focus on the impact of environmental factors, are summarized. First, this manuscript introduces potentially contaminated foodstuffs, including the emerging ones which are not regulated in international legislation. Secondly, it gives an update of native producers based on foodstuffs and OTA biosynthesis. Thirdly, complicated environmental regulation is disassembled into individual factors in order to clarify their regulatory effect and mechanism. Finally, to emphasize control OTA at all stages of foodstuffs from farm to table, strategies used at crop planting, harvest, storage and processing stages are discussed.

Production of Aflatoxin B1 by Aspergillus parasiticus Grown on a Novel Meat-Based Media

The aim of the present study was to develop meat-based media with compositions similar to those of dry-fermented meat products and to evaluate their use in studying the growth of Aspergillus parasiticus and the kinetics of aflatoxin B1 (AFB1) production. In our previous experiments, we found that the strain A. parasiticus ŽMJ7 produced a high amount of AFB1. Cooked meat agar (CMA2) was used as a novel complex meat-based medium with four variations: CMA2G (CMA2 supplemented with 1% glucose), CMA2YE (CMA2 supplemented with 0.2% yeast extract), and CMA2GYE (CMA2 supplemented with 1% glucose and 0.2% yeast extract). Media were inoculated with an A. parasiticus spore suspension (105 spores/mL) and incubated at 25 °C for up to 15 days. The A. parasiticus lag phase lasted less than 1 day, irrespective of the growth medium, with the exception of control medium CMA1 (cooked meat agar) as an already known meat-based medium. The highest mean colony growth rate was observed on CMA2 and CMA2G. Reversed-phase UPLC-MS/MS analysis was performed to determine the AFB1 concentration in combination with solid phase extraction (SPE). The highest AFB1 concentration in meat-based media was detected in CMA2GYE after 15 days of incubation (13,502 ± 2367 ng/mL media). The results showed that for studying AFB1 production in dry-fermented meat products, novel suitable media such as CMA2-based media are required. This finding could represent a potential concern with regard to the production of dry-fermented meat products.

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.

Gene expression profiling after ochratoxin A treatment in small intestinal epithelial cells from pigs

Ochratoxin A (OTA) is a well-known mycotoxin that causes disease through the ingestion of contaminated food or feed, for example, in the porcine industry. The intestinal epithelium acts as the first barrier against food contamination. We conducted a study on the exposure of the porcine intestinal epithelium to OTA. We used the intestinal porcine epithelial cell line IPEC-J2 as an in vitro model to evaluate the altered molecular mechanisms following OTA exposure. Gene expression profiling revealed that OTA upregulated 782 genes and downregulated 896, totalling 1678 differentially expressed genes. Furthermore, immunofluorescence, quantitative real-time polymerase chain reaction, and western blotting confirmed that OTA damages the tight junction protein ZO-1. Moreover, OTA activated the expression of inflammatory genes (IL-6, IL-8, IL-10, NF-kB, TLR4, and TNF-α). In summary, this study confirmed that OTA alters various molecular mechanisms and has several adverse effects on IPEC-J2 cells.

Investigation of ochratoxin a in blood sausages in the Czech Republic: Comparison with data over Europe

Blood sausages consisting of groats, pork, porcine offal, fat, blood, and spices are very popular in the Czech Republic. All these ingredients are potential sources of dietary exposure to ochratoxin A (OTA). OTA has a strong affinity to serum proteins in porcine blood. Thus, the contamination of blood sausages with OTA can be expected. This study aims to evaluate OTA in 200 samples of porcine blood sausages purchased at the Czech market during 2020-2021. The analytical method high-performance liquid chromatography coupled with fluorescence detection with pre-treatment using immunoaffinity columns was employed to determine OTA. The limit of detection was 0.03 ng/g and the limit of quantification 0.10 ng/g. Recovery was 71.6 %. All samples were positive at contents ranging from 0.15 to 5.68 ng/g with a mean of 1.47 ng/g, and a median of 1.26 ng/g. A total of 66% of these samples contained OTA content exceeding the maximum limit of 1 ng/g set in Italy. This study demonstrates that the Czech population is exposed to OTA from blood sausages. The proposed preliminary action limit for OTA in blood sausages should be set at 1 ng/g. No regulatory limits for OTA in blood sausages have been established yet in the European Union legislation. To protect human health, further monitoring of OTA in these products is necessary.

Recent developments in off-odor formation mechanism and the potential regulation by starter cultures in dry-cured ham

Foul-smelling odors are main quality defects of dry-cured ham, which are connected with the excessive degradation of the structural proteins and excessive oxidation of lipids caused by the abnormal growth of spoilage microorganisms, threatening the development of dry-cured ham industry. Characterizing the key microorganisms and metabolites resulted in the spoilage of dry-cured ham, and discussing the relationship between spoilage microorganisms and metabolites are the key aspects to deeply understand the formation mechanism of off-odor in dry-cured ham. Until now, there is no detailed discussion or critical review on the role of spoilage microorganisms in developing the off-odor of dry-cured ham, and the regulation of off-odor and spoilage microorganisms by starter cultures has been not discussed. This review shows the recent achievement in the off-odor formation mechanism of dry-cured ham, and outlines the potential regulation of off-odor defects in dry-cured ham by starter cultures. Results from current research show that the abnormal growth of Lactic acid bacteria, Micrococcaceae, Enterobacteriaceae, Yeasts and Molds plays a key role in developing the off-odor defects of dry-cured ham, while the key spoilage microorganisms of different type hams are discrepant. High profile of aldehydes, acids, sulfur compounds and biogenic amines are responsible for off-odor development in spoiled dry-cured ham. Several starter cultures derived from these species of Staphylococcus, Penicillium, Debaryomyces, Pediococcus and Lactobacillus show a great potential to prevent microbiological hazards and improve flavor quality of dry-cured ham, whereas, the ecology, function and compatibility of these starter cultures with the processing parameters of dry-cured ham need to be further evaluated in the future.

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.

Potential of Near Infrared Spectroscopy as a Rapid Method to Discriminate OTA and Non-OTA-Producing Mould Species in a Dry-Cured Ham Model System

The ripening process of dry-cured meat products is characterised by the development of fungi on the product's surface. This population plays a beneficial role, but, uncontrolled moulds represent a health risk, since some of them may produce mycotoxins, such as ochratoxin A (OTA). The aim of the present work is to assess the potential of near-infrared spectroscopy (NIRS) for the detection of OTA-producing mould species on dry-cured ham-based agar. The collected spectra were used to develop Support Vector Machines-Discriminant Analysis (SVM-DA) models by a hierarchical approach. Firstly, an SVM-DA model was tested to discriminate OTA and non-OTA producers; then, two models were tested to discriminate species among the OTA producers and the non-OTA producers. OTA and non-OTA-producing moulds were discriminated with 85% sensitivity and 86% specificity in the prediction. Furthermore, the SVM-DA model could differentiate non-OTA-producing species with a 95% sensitivity and specificity. Promising results were obtained for the prediction of the four OTA-producing species tested, with a 69% and 90% sensitivity and specificity, respectively. The preliminary approach demonstrated the high potential of NIR spectroscopy, coupled with Chemometrics, to be used as a real-time automated routine monitorization of dry-cured ham surfaces.

A PCR method to identify ochratoxin A-producing Aspergillus westerdijkiae strains on dried and aged foods

Ochratoxins are a group of mycotoxins that frequently occur as contaminants in agricultural commodities and foods, including dry-cured meats and cheeses. The fungus Aspergillus westerdijkiae is frequently isolated from aged foods and can produce ochratoxin A (OTA). However, individual strains of the fungus can have one of two OTA production phenotypes (chemotypes): OTA production and OTA nonproduction. Monitoring and early detection of OTA-producing fungi in food are the most effective strategies to manage OTA contamination. Therefore, we examined genome sequence data from five A. westerdijkiae strains isolated from the surface of cheese from southern Italy to identify genetic markers indicative of the twoOTA chemotypes. This analysis revealed a naturally occurring deletion of the OTA regulatory gene, otaR, in an OTA-nonproducing isolate.We used this information to design a polymerase chain reaction (PCR) method that could identify A. westerdijkiae and distinguish between the two OTA chemotypes. In this method, the PCR primers were complementary to conserved sequences flanking otaR and yielded different-sized amplicons from strains with the different chemotypes. The primers did not yield ota-region-specific amplicons from other OTA-producing species. Because the method is specific to A. westerdijkiae and can distinguish between the two OTA chemotypes, it has potential to significantly improve OTA monitoring programs.

Influence of an industrial dry-fermented sausage processing on ochratoxin A production by Penicillium nordicum

Dry-fermented sausages are prone to be colonised by Penicillium nordicum, which is one of the main ochratoxin A (OTA)-producing species. Its ability to produce this mycotoxin on dry-fermented sausages has been reported. However, the influence of the conditions of a traditional processing of a Spanish dry-fermented sausage and the intrinsic physicochemical parameters of this product such as water activity (a_w) and pH on OTA production has not been studied yet. Thus, the aim of this study was to evaluate the influence of traditional processing (interaction of relative humidity (RH) x temperature x ripening days) on the evolution of pH and a_w during maturation of dry-fermented sausage "salchichón" and its relationship with OTA synthesis by P. nordicum. The expression of otapks and otanps genes, both involved in the biosynthesis of the mycotoxin, was also assessed. For this, 27 raw sausages were inoculated with P. nordicum and ripened for 26 days in a drying chamber (3 days at 5 °C and 84% RH, 17 days at 12 °C and 84% RH, and 6 days at 12 °C and 80% RH). From results, although it seems that the pH slightly influenced on OTA biosynthesis, the a_w had a great impact on this mycotoxin production. In fact, the two highest OTA concentrations found coincided with a dramatic rise of the a_w value (0.92 a_w) by day 18 of incubation when the RH of the drying chamber was still 84% and at the end of the incubation time when the a_w decreased noticeably (0.87 a_w). The expression of the otapks and otanps genes correlated with the OTA produced by P. nordicum. Results from this work confirm that the traditional processing of Spanish dry-fermented sausages favours itself OTA synthesis by P. nordicum. Our findings may help in informed decision-making in relation to RH/temperature of drying chambers and shortening of the ripening process. This may be then effectively incorporated into the hygienic production system in the framework of HACCP together with other measures including the use of Penicillium nalgiovense as protective culture or the monitoring of otapks gene expression, and a_w during the processing of dry-fermented sausages. All these strategies together may put ochratoxigenic Penicillia at a disadvantage and minimise OTA contamination risks in dry-fermented sausages.

Effect of a Debaryomyces hansenii and Lactobacillus buchneri Starter Culture on Aspergillus westerdijkiae Ochratoxin A Production and Growth during the Manufacture of Short Seasoned Dry-Cured Ham

Recently, specific dry-cured hams have started to be produced in San Daniele and Parma areas. The ingredients are similar to protected denomination of origin (PDO) produced in San Daniele or Parma areas, and include pork leg, coming from pigs bred in the Italian peninsula, salt and spices. However, these specific new products cannot be marked as a PDO, either San Daniele or Parma dry cured ham, because they are seasoned for 6 months, and the mark PDO is given only to products seasoned over 13 months. Consequently, these products are called short-seasoned dry-cured ham (SSDCH) and are not branded PDO. During their seasoning period, particularly from the first drying until the end of the seasoning period, many molds, including Eurotium spp. and Penicillium spp., can grow on the surface and work together with other molds and tissue enzymes to produce a unique aroma. Both of these strains typically predominate over other molds. However, molds producing ochratoxins, such as Aspergillus ochraceus and Penicillium nordicum, can simultaneously grow and produce ochratoxin A (OTA). Consequently, these dry-cured hams may represent a potential health risk for consumers. Recently, Aspergillus westerdijkiae has been isolated from SSDCHs, which could represent a potential problem for consumers. Therefore, the aim of this study was to inhibit A. westerdijkiae using Debaryomyces hansenii or Lactobacillus buchneri or a mix of both microorganisms. Six D. hansenii and six L. buchneri strains were tested in vitro for their ability to inhibit A. westerdijkiae. The strains D. hansenii (DIAL)1 and L. buchneri (Lb)4 demonstrated the highest inhibitory activity and were selected for in situ tests. The strains were inoculated or co-inoculated on fresh pork legs for SSDCH production with OTA-producing A. westerdijkiae prior to the first drying and seasoning. At the end of seasoning (six months), OTA was not detected in the SSDCH treated with both microorganisms and their combination. Because both strains did not adversely affect the SSDCH odor or flavor, the combination of these strains are proposed for use as starters to inhibit OTA-producing A. westerdijkiae.

Determination of ochratoxin A in edible pork offal: intra-laboratory validation study and estimation of the daily intake via kidney consumption in Belgium

Pork-derived products can contribute to the overall ochratoxin A (OTA) intake via carry-over from contaminated feed or via mould spoilage of meat products (salami, dry-cured ham, sausage). An analytical method using liquid chromatography coupled with mass spectrometry (LC-MS/MS) was developed and validated in accordance with the specifications laid down by European Commission. It offered quantification limits of 0.2 for kidney, liver and 0.4 μg/kg for black sausage. Spiking experiments of blank samples at 5-10 μg/kg showed recoveries ranging from 88 to 101%, 89 to 97% and 80 to 85% for kidney, liver and black sausage, respectively. The respective intra-laboratory repeatabilities ranged between 9.8-11.1%, 9.4-14.4% and 9.7-14.2%, and extended measurement uncertainties MU_(k = 2) were 33%, 35% and 43% for kidney, liver and black sausage. Next, the validated method was applied to kidney (110), liver (20) and black sausage (20) samples collected in Belgium in the period 2012-2019. Neither liver nor black sausage samples were contaminated with OTA. Kidney samples (37.3%) were OTA contaminated at the mean level of 0.22 ± 0.25 μg/kg (up to 1.91 μg/kg). These data combined with the offal consumption in the Belgian population revealed average daily OTA exposures ranged from 0.167 and 0.319 ng/kg bw for 3 age groups (3-9, 10-17 and 18-64 years). Taking into account, the OTA non-neoplastic and neoplastic effects, risk characterization assessed via the margin of exposure for reference endpoints revealed no potential health risk for the consumers. As the presence of low OTA content in foods together with other mycotoxins or derivatives may interactively potentiate its toxicity, monitoring of OTA and its metabolites in meat and meat by-products is advised.

Selection and Evaluation of Staphylococcus xylosus as a Biocontrol Agent against Toxigenic Moulds in a Dry-Cured Ham Model System

Toxigenic moulds can develop on the surface of dry-cured meat products during ripening due to their ecological conditions, which constitutes a risk for consumers. A promising strategy to control this hazard is the use of antifungal microorganisms usually found in these foods. However, to date, the effectiveness of gram-positive catalase-positive cocci (GCC+) has not been explored. The aim of this work was to select GCC+ isolates with antifungal activity to study its effectiveness in a dry-cured ham model system at the environmental conditions reached during the ripening. Forty-five strains of GCC+ were evaluated and the isolate Staphylococcus xylosus Sx8 was selected to assess its efficacy at two different concentrations (106 and 104 cfu/mL) against Penicillium nordicum, Aspergillus flavus, Aspergillus parasiticus, and Penicillium griseofulvum at 15, 20, and 25 °C. The results showed that the inoculation of 106 cfu/mL of S. xylosus completely inhibited the growth of most fungi. In addition, in the presence of this strain at 104 cfu/mL, a significant reduction in fungal growth and mycotoxins production was observed at the three temperatures studied. In conclusion, S. xylosus Sx8 possesses great potential as a biological agent to control toxigenic moulds in dry-cured meat products.

Effects of mycotoxin-contaminated feed on farm animals

Mycotoxins are secondary products produced by fungi in cereals and are frequently found in the livestock industry as contaminants of farm animal feed. Studies analyzing feed mycotoxins have been conducted worldwide and have confirmed the presence of mycotoxins with biological activity, including aflatoxin, ochratoxin A, fumonisin, zearalenone, and deoxynivalenol, in a large proportion of feed samples. Exposure to mycotoxins can cause immunotoxicity and impair reproductive function in farm animals. In addition, exposure of tissues, such as the kidneys, liver, and intestines, to mycotoxins can exert histopathological changes that can interfere with animal growth and survival. This review describes previous studies regarding the presence of major mycotoxins in the feed of farm animals, especially pigs and poultry. Moreover, it describes the adverse effects of mycotoxins in farm animals following exposure, as well as the biological activity of mycotoxins in animal-derived cells. Mycotoxins have been shown to regulate signaling pathways, oxidative stress, endoplasmic reticulum stress, apoptosis, and proliferation in porcine and bovine cells. A clear understanding of the effects of mycotoxins on farm animals will help reduce farm household economic loss and address the health concerns of people who consume these meat and dairy products.

Risk assessment of ochratoxin A in food

The European Commission asked EFSA to update their 2006 opinion on ochratoxin A (OTA) in food. OTA is produced by fungi of the genus Aspergillus and Penicillium and found as a contaminant in various foods. OTA causes kidney toxicity in different animal species and kidney tumours in rodents. OTA is genotoxic both in vitro and in vivo; however, the mechanisms of genotoxicity are unclear. Direct and indirect genotoxic and non-genotoxic modes of action might each contribute to tumour formation. Since recent studies have raised uncertainty regarding the mode of action for kidney carcinogenicity, it is inappropriate to establish a health-based guidance value (HBGV) and a margin of exposure (MOE) approach was applied. For the characterisation of non-neoplastic effects, a BMDL 10 of 4.73 μg/kg body weight (bw) per day was calculated from kidney lesions observed in pigs. For characterisation of neoplastic effects, a BMDL 10 of 14.5 μg/kg bw per day was calculated from kidney tumours seen in rats. The estimation of chronic dietary exposure resulted in mean and 95th percentile levels ranging from 0.6 to 17.8 and from 2.4 to 51.7 ng/kg bw per day, respectively. Median OTA exposures in breastfed infants ranged from 1.7 to 2.6 ng/kg bw per day, 95th percentile exposures from 5.6 to 8.5 ng/kg bw per day in average/high breast milk consuming infants, respectively. Comparison of exposures with the BMDL 10 based on the non-neoplastic endpoint resulted in MOEs of more than 200 in most consumer groups, indicating a low health concern with the exception of MOEs for high consumers in the younger age groups, indicating a possible health concern. When compared with the BMDL 10 based on the neoplastic endpoint, MOEs were lower than 10,000 for almost all exposure scenarios, including breastfed infants. This would indicate a possible health concern if genotoxicity is direct. Uncertainty in this assessment is high and risk may be overestimated.

Competitiveness of three biocontrol candidates against ochratoxigenic Penicillium nordicum under dry-cured meat environmental and nutritional conditions

The environmental conditions during the ripening of dry-cured meats and their nutritional composition promote the colonisation of their surface by Penicillium spp., including P. nordicum producer of ochratoxin A (OTA). The objective of this work was to study the competitiveness of three potential biocontrol candidates (Debaryomyces hansenii FHSCC 253H, Enterococcus faecium SE920 and Penicillium chrysogenum CECT, 20922) against the ochratoxigenic P. nordicum FHSCC4 under environmental and nutritional conditions simulating the ripening of dry-cured meat products. For this, the nutritional utilisation pattern, niche overlap index (NOI), interactions by dual-culture assays and OTA production were determined. The number of carbon sources (CSs) metabolised depended on the microorganism and the interacting water activity (a_w) x temperature conditions. The number of CSs utilised by both filamentous fungi was quite similar and higher than those utilised by D. hansenii and E. faecium. The yeast isolate metabolised a number of CSs much larger than the bacterium. The NOI values showed that, in general, P. nordicum nutritionally dominated E. faecium and D. hansenii regardless of the environmental conditions evaluated. The relationship between the toxigenic and non-toxigenic fungal isolates depended on the a_w x temperature combinations, although in none of the conditions a dominance of P. nordicum was observed. According to the interaction assays, both D. hansenii and P. chrysogenum decreased the growth of P. nordicum. The effect of D. hansenii could be attributed to the production of some extra-cellular compounds, while the action of P. chrysogenum is likely related to nutritional competition. In addition, both P. chrysogenum and D. hansenii reduced the OTA levels produced by P. nordicum. The effect of the yeast was more pronounced decreasing the concentration of OTA at quantities lower than the limit established by the Italian legislation. Therefore, P. chrysogenum and D. hansenii can be suggested as biocontrol candidates in the manufacture of dry-cured meat products.

Determination of ochratoxin A in pork meat products: single laboratory validation method and preparation of homogeneous batch materials

Ochratoxin A is one of the most diffused mycotoxin present in a large spectrum of food commodities, mainly produced by Aspergillus ochraceus, Aspergillus carbonarius, Aspergillus niger and Penicillium verrucosum. EU has set maximum limits for a number of matrices such as cereals, wine, spices and liquorice, whilst other commodities such as beer and meat products that are susceptible of OTA contamination and are largely consumed are not included. In 2013, within the framework of the Regulation (EC) 882/2004 on official controls, the European Commission issued the mandate M/520 regarding the standardisation for methods of analysis for mycotoxins in food to the European Committee for Standardisation. Of the 11 priorities of the mandate, the one on "HPLC determination of OTA in meat, meat products and edible offal" was assigned to the Italian National Reference Laboratory for feed and food. The method was single-laboratory validated, and all the performance characteristics of the method were compliant with the corresponding reference values indicated in Regulation (EC) n. 401/2006. The method was applied to characterise a set of 5 pork-based materials (ham, kidney, liver and canned chopped pork) to be used for an inter-laboratory method validation study. Three ham materials (levels of contamination of 0.77, 2.22 and 12.3 μg/kg, respectively), one liver material (contamination level of 2.80 μg/kg) and one chopped pork meat (contamination level of 0.66 μg/kg) were tested for homogeneity and stability.

Efficacy of the Combined Protective Cultures of Penicillium chrysogenum and Debaryomyces hansenii for the Control of Ochratoxin A Hazards in Dry-Cured Ham

The ecological conditions during the ripening of dry-cured ham favour the development of moulds on its surface, being frequently the presence of Penicillium nordicum, a producer of ochratoxin A (OTA). Biocontrol using moulds and yeasts usually found in dry-cured ham is a promising strategy to minimize this hazard. The aim of this work is to evaluate the effect of previously selected Debaryomyces hansenii and Penicillium chrysogenum strains on growth, OTA production, and relative expression of genes involved in the OTA biosynthesis by P. nordicum. P. nordicum was inoculated against the protective cultures individually and combined on dry-cured ham for 21 days at 20 °C. None of the treatments reduced the growth of P. nordicum, but all of them decreased OTA concentration. The lower production of OTA could be related to significant repression of the relative expression of otapksPN and otanpsPN genes of P. nordicum. The efficacy of the combined protective cultures was tested in 24 dry-cured hams in industrial ripening (an 8 month-long production). OTA was detected in nine of the 12 dry-cured hams in the batch inoculated only with P. nordicum. However, in the batch inoculated with both P. nordicum and the combined protective culture, a considerable reduction of OTA contamination was observed. In conclusion, although the efficacy of individual use P. chrysogenum is great, the combination with D. hansenii enhances its antifungal activity and could be proposed as a mixed protective culture to control the hazard of the presence of OTA in dry-cured ham.

A study of surface moulds and mycotoxins in Croatian traditional dry-cured meat products

Xerophilic species of Aspergillus, Penicillium and Eurotium genera from surfaces of dry-cured traditional meat products (TMPs) can cause mycotoxin contamination during uncontrolled household processing. The aim of this study was to investigate into surface moulds growing on Croatian prosciuttos and fermented sausages produced in different climate regions using different technologies (n = 160), and to relate the occurrence of aflatoxin B₁ (AFB₁) and ochratoxin A (OTA) to their presence. The results revealed the Penicillium (79%) to be the dominating contaminating mould, while Aspergillus (11%), Eurotium (7%) and Mucor (4%) species were present in a significantly lower number of isolates, with higher prevalence and greater diversity in prosciuttos than in sausages, relative of the production technology and regional climate. OTA contamination (14% of samples) was significantly more frequent than that with AFB₁ (8% of samples), with OTA concentration rising to the maximal 6.86 μg/kg, whereas AFB₁ concentrations were slightly higher than, or around, the limit of quantification of the method in use, with the maximal value of 1.92 μg/kg. The presence of AFB₁ in absence of toxicogenic moulds, observed in some samples, can be attributed to contaminated spices used in TMP production or an indirect contamination via a carry-over effect.

Enterococcus faecium: a promising protective culture to control growth of ochratoxigenic moulds and mycotoxin production in dry-fermented sausages

Moulds positively contribute to the development of typical characteristic flavour and aroma of dry-fermented sausages. However, some mould species, such as Penicillium nordicum and Penicillium verrucosum, may contaminate this product with ochratoxin A (OTA). For this reason, the control of toxigenic moulds is needed. Strategies based on the use of antifungal microorganisms present in the native microbial population in the dry-fermented sausage processing could be a promising strategy. The aim of this work was to study the effect of Enterococcus faecium strains on P. nordicum and P. verrucosum growth and OTA production in a dry-fermented sausage-based medium at conditions of temperature and water activity similar to those occurring during the ripening of these meat products. Six strains were screened to evaluate their growth capacity and antifungal activity against P. nordicum and P. verrucosum at three fixed temperatures related to the sausage ripening. The two E. faecium strains that decreased growth of both species were chosen to further evaluate their effect on growth of P. verrucosum and P. nordicum and their mycotoxin production under conditions simulating the dry-fermented sausage ripening. The presence of E. faecium SE920 significantly reduced OTA production of P. nordicum although it did not affect P. verrucosum. E. faecium SE920, isolated from dry-fermented sausages, could be a good candidate to reduce OTA production by P. nordicum in dry-fermented sausages.

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

The objectives of the present work were to survey, for the first time, the contamination of Portuguese fresh and dry-cured meat products with ochratoxin A (OTA) and aflatoxin B₁ (AFB₁), and to determine the fungi potentially responsible for this contamination. A total of 128 samples including pork fresh legs, dry-cured legs and shoulders, as well as goat and sheep dry-cured legs were analysed. Mycological analysis of these samples yielded a total of 630 fungal isolates. Penicillium sp. was the dominant fungal genus in all products (66% of all isolates). Penicillium nordicum and Aspergillus westerdijkiae were only rarely isolated from pork ham samples. In fresh pork meat, 40% of the samples were contaminated with OTA at levels below 1 μg/kg. In pork dry-cured legs with 20 to 25 months of ripening, 43% of the samples showed detectable contamination, while 18% of the shoulder hams were contaminated. OTA was not detected in any of the goat and sheep samples. OTA contamination does not seem to be a risk in small-piece and short-ripe products like goat and sheep legs, but affects longer ripe products like pork legs and shoulders. Although aflatoxigenic fungi were identified, AFB₁ was not detected in any sample, and it should not be considered a risk in dry-cured hams.

Role of Starter Cultures on the Safety of Fermented Meat Products

Starters are microbial cultures used to promote and conduct the fermentation of meat products. Bacteria, particularly lactic acid bacteria (LAB) and coagulase-negative staphylococci (CNS), as well as yeasts and molds, may be used as starters. They can increase the safety of fermented meat products by means of rapid matrix acidification or due to the production of antimicrobial substances, such as bacteriocins. Besides, starters may help to standardize product properties and shorten ripening times. Safety of fermented meat products may be jeopardized by microbiological, namely foodborne pathogens (Salmonella spp., Listeria spp., etc), and chemical hazards, particularly biogenic amines, nitrosamines, polycyclic aromatic hydrocarbons (PAH), and mycotoxins. Biogenic amines (BA) are potentially unsafe nitrogenous compounds that result from the decarboxylation of some amino acids. Some microorganisms may be responsible for their formation. Starters can cause a fast pH decrease, inhibiting the development of microorganisms with amino acid decarboxylative ability, thus preventing the accumulation of BA in fermented meat products. Besides, starters can compete with the autochthonous, non-starter microbiota throughout ripening and storage, thus reducing BA production. Some strains of Lactobacillus sakei and Lactobacillus plantarum have been shown to reduce the formation/accumulation of BA. On the other hand, Staphylococcus xylosus and Debaryomyces hansenii strains have been reported to degrade BA in food. PAH are organic compounds containing multiple aromatic rings and produced by the incomplete combustion of organic matter, such as the wood used for smoking meat. Mixed starters containing Lactobacillus spp., Gram-positive catalase-positive cocci and yeasts have been used in the manufacturing of traditional meat sausages. However, the effect of starters on reducing the accumulation of PAH is poorly understood. Starters may also be engaged in competitive exclusion, outcompeting the spoiling or deteriorating autochthonous microbiota. For example, Pediococcus acidilactici has been shown to inhibit Listeria monocytogenes in meat products. Additionally, the role of molds, such as Penicillium nalgiovense, in the competitive exclusion of undesired filamentous fungi, has also been demonstrated. Most of these undesired fungi produce mycotoxins, secondary metabolites capable of causing disease. The current review addresses the role of starters on the microbiological and chemical safety of fermented meat products.

Relationship between cyclopiazonic acid production and gene expression in Penicillium griseofulvum under dry-cured ham processing environmental conditions

Cyclopiazonic acid (CPA)-producing Penicillium griseofulvum is usually found on the dry-cured ham surface during its ripening. The objective of this work was to evaluate the effect of temperature and water activity (a_w) of dry-cured ham processing on growth, CPA production, and temporal relative expression of genes involved in CPA biosynthesis on dry-cured meat-based media. P. griseofulvum CECT 2919 grew faster than P. griseofulvum IBT 14319 in all conditions tested, although no growth occurred at 0.85 a_w. Besides, the dry-cured ham-based medium favoured CPA synthesis for both strains compared to the meat-based medium. For the strain CECT 2919, the expression of the mfs-1 and pks-nrps genes were stimulated at 0.90 and 0.95 a_w, respectively, while the dmaT gene expression was inhibited during the incubation time. By contrast, the strain IBT 14319 showed that the dmaT gene expression was stimulated at 0.90 a_w, while the pks-nrps and mfs-1 genes were repressed throughout incubation time. In conclusion, it is necessary to reduce a_w on the surface of the hams below 0.85 during ripening before to increase temperature to reduce growth of P. griseofulvum and CPA production. This information may be useful to design preventive and corrective actions to minimise risks associated with the presence of CPA in dry-cured ham.

Biocontrol of aflatoxigenic Aspergillus parasiticus by native Debaryomyces hansenii in dry-cured meat products

Dry-cured meat products, such as dry-cured ham or dry-fermented sausages, are characterized by their particular ripening process, where a mould population grows on their surface. Some of these moulds are hazardous to the consumers because of their ability to produce mycotoxins including aflatoxins (AFs). The use of native yeasts could be considered a potential strategy for controlling the presence of AFs in dry-cured meat products. The aim of this work was to evaluate the antagonistic activity of two native Debaryomyces hansenii strains on the relative growth rate and the AFs production in Aspergillus parasiticus. Both D. hansenii strains significantly reduced the growth rates of A. parasiticus when grown in a meat-model system at different water activity (a_w) conditions. The presence of D. hansenii strains caused a stimulation of AFs production by A. parasiticus at 0.99 a_w. However, at 0.92 a_w the yeasts significantly reduced the AFs concentration in the meat-model system. The relative expression levels of the aflR and aflS genes involved in the AFs biosynthetic pathway were also repressed at 0.92 a_w in the presence of both D. hansenii strains. These satisfactory results were confirmed in dry-cured ham and dry-fermented sausage slices inoculated with A. parasiticus, since both D. hansenii strains significantly reduced AFs amounts in these matrices. Therefore, both tested D. hansenii strains could be proposed as biocontrol agents within a HACCP framework to minimize the hazard associated with the presence of AFs in dry-cured meat products.

Biocontrol of Penicillium griseofulvum to reduce cyclopiazonic acid contamination in dry-fermented sausages

Dry-fermented sausages are very appreciated by consumers. The environmental conditions during its ripening favor colonization of their surface by toxigenic molds. These molds contribute to the development of sensory characteristics; however, some of them could produce mycotoxins such as cyclopiazonic acid (CPA). CPA is mainly produced by Penicillium commune and Penicillium griseofulvum which have been found in dry-cured meat products. Thus, strategies to prevent the CPA contamination in dry-fermented sausages are needed. The objective of this work was to evaluate the ability of P. griseofulvum to produce CPA in dry-fermented sausage during its ripening as well as to test different strategies to prevent CPA production. The ability of PgAFP antifungal protein-producing Penicillium chrysogenum, Debaryomyces hansenii and Pediococcus acidilactici for inhibiting CPA production by P. griseofulvum was tested on dry-fermented sausage-based medium. Only P. chrysogenum inhibited the CPA production, so this mold was co-inoculated with P. griseofulvum on sausages whose ripening was performed at low temperature. CPA reached around 800 ng/g in the control batch, being reduced to 20 ng/g by the presence of P. chrysogenum. This work demonstrates the risk posed by CPA on dry-fermented sausages, and provides a successful strategy to prevent this hazard.

Effects of environmental conditions and substrate on growth and ochratoxin A production by Penicillium verrucosum and Penicillium nordicum: Relative risk assessment of OTA in dry-cured meat products

Ecological conditions during ripening of dry-cured meat products favour the growth of an uncontrolled mould population that could suppose a risk of ochratoxin A (OTA) production. In this work the influence of water activity (a_w), temperature and substrate composition on fungal growth and OTA production by Penicillium nordicum and Penicillium verrucosum isolated from dry-cured meat products have been studied. In addition, the relative risk of OTA presence on dry-cured meat products has been evaluated using the Risk Ranger software. Fungal growth was observed in the range of 0.99-0.90 a_w and 15-25 °C being mainly temperature-dependent. P. nordicum and P. verrucosum were able to produce OTA in every substrate in these ranges of a_w and temperature. The production of OTA by P. verrucosum was mainly influenced by temperature and media composition. However, P. nordicum it is affected mainly by substrate or temperature depending on the strain studied. Both species produce a large amount of OTA on dry-cured ham and on dry-cured fermented sausage "salchichón" in environmental conditions usually found throughout the ripening of these products. The Risk Ranger software reveals that the relative risk of OTA on dry-cured meat products is 75%. Thus, control measures during dry-cured meat products processing to prevent OTA risk should be established.

Inhibitory Effect of PgAFP and Protective Cultures on Aspergillus parasiticus Growth and Aflatoxins Production on Dry-Fermented Sausage and Cheese

Aflatoxigenic molds can grow and produce aflatoxins on dry-fermented meat and cheese. The small, basic, cysteine-rich antifungal protein PgAFP displays a time-limited inhibitory ability against unwanted molds by increasing reactive oxygen species (ROS), which can lead to increased aflatoxin production. However, calcium abolishes the inhibitory effect of PgAFP on certain Aspergillus spp. To maximize the antifungal effect, this protein may be combined with protective cultures. Yeasts and lactic acid bacteria may counteract the impact of calcium on PgAFP fungal inhibition. The objective of this work was to study the effect of PgAFP and different combined treatments with Debaryomyces hansenii and/or Pediococcus acidilactici against growth of and aflatoxin production by an aflatoxigenic strain of Aspergillus parasiticus in both culture media and dry-fermented foods with low or high calcium levels. Aflatoxins production was increased by PgAFP but dramatically reduced by P. acidilactici in low calcium culture medium, whereas in the Ca-enriched culture medium, all treatments tested led to low aflatoxins levels. To study whether PgAFP and the protective microorganisms interfere with ROS and aflatoxin production, the relative expression of genes foxA, which is involved in peroxisomal β-oxidation, and aflP, which is required for aflatoxin biosynthesis, were evaluated. The aflatoxin overproduction induced by PgAFP seems not to be linked to peroxisomal β-oxidation. The combination of PgAFP and D. hansenii provided a successful inhibitory effect on A. parasiticus growth as well as on aflatoxin production on sliced dry-fermented sausage and cheese ripened up to 15 days, whereas P. acidilactici did not further enhance the protective effect of the two former agents. Therefore, the combined treatment of PgAFP and D. hansenii seems to provide a promising protective mean against aflatoxin-producing A. parasiticus on dry-fermented foods.