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

Unveiling the emerging role of curcumin to alleviate ochratoxin A-induced muscle toxicity in grass carp (Ctenopharyngodon idella): in vitro and in vivo studies

BACKGROUND

Ochratoxin A (OTA), a globally abundant and extremely hazardous pollutant, is a significant source of contamination in aquafeeds and is responsible for severe food pollution. The developmental toxicity of OTA and the potential relieving strategy of natural products remain unclear. This study screened the substance curcumin (Cur), which had the best effect in alleviating OTA inhibition of myoblast proliferation, from 96 natural products and investigated its effect and mechanism in reducing OTA myotoxicity in vivo and in vitro.

METHODS

A total of 720 healthy juvenile grass carp, with an initial average body weight of 11.06 ± 0.05 g, were randomly assigned into 4 groups: the control group (without OTA and Cur), 1.2 mg/kg OTA group, 400 mg/kg Cur group, and 1.2 mg/kg OTA + 400 mg/kg Cur group. Each treatment consisted of 3 replicates (180 fish) for 60 d.

RESULTS

Firstly, we cultured, purified, and identified myoblasts using the tissue block culture method. Through preliminary screening and re-screening of 96 substances, we examined cell proliferation-related indicators such as cell viability and ultimately found that Cur had the best effect. Secondly, Cur could alleviate OTA-inhibited myoblast differentiation and myofibrillar development-related proteins (MyoG and MYHC) in vivo and in vitro and improve the growth performance of grass carp. Then, Cur could also promote the expression of OTA-inhibited protein synthesis-related proteins (S6K1 and TOR), which was related to the activation of the AKT/TOR signaling pathway. Finally, Cur could downregulate the expression of OTA-enhanced protein degradation-related genes (murf1, foxo3a, and ub), which was related to the inhibition of the FoxO3a signaling pathway.

CONCLUSIONS

In summary, our data demonstrated the effectiveness of Cur in alleviating OTA myotoxicity in vivo and in vitro. This study confirms the rapidity, feasibility, and effectiveness of establishing a natural product screening method targeting myoblasts to alleviate fungal toxin toxicity.

Occurrence of ochratoxin A in Sichuan bacon from different geographical regions and characterization and biocontrol of ochratoxigenic Aspergillus westerdijkiae strain 21G2-1A

Sichuan bacon represents the most prevalent dry-cured meat product across Southwest China, but it is vulnerable to fungal spoilage. In the present study, a total of 47 Sichuan bacons were obtained from different regions of the Sichuan Province and analyzed for the presence of ochratoxin A (OTA), yielding a positive rate of 23.4 % (11/47). All the observed OTA concentrations exceeded the maximum admissible dose in meat products (1 μg/kg) established by some EU countries, with the highest OTA concentration being 250.75 μg/kg, which raises a food safety concern and reveals the need for a standardized scientific processing protocol. Then, an OTA-producing fungus named 21G2-1A was isolated from positive samples and found to be Aspergillus westerdijkiae. Further characterization suggested a positive correlation between fungal growth and OTA production. The optimal temperature for the former was 25 °C, while it was 20 °C for the latter. Although the A. westerdijkiae strain 21G2-1A demonstrated greater mycelium growth in the presence of NaCl, OTA production was significantly dismissed when the salinity was greater than 5 %. Four lactic acid bacteria (LAB) were screened out as antagonists against the ochratoxigenic fungus. In vitro evaluation of the antagonists revealed that live cells inhibited fungal growth, and adsorption also contributed to OTA removal at different levels. This study sheds some light on OTA control in Sichuan bacon through a biological approach.

Relevant mycotoxins in oil crops, vegetable oils, de-oiled cake and meals: Occurrence, control, and recent advances in elimination

Mycotoxins in agricultural commodities have always been a concern due to their negative impacts on human and livestock health. Issues associated with quality control, hot and humid climate, improper storage, and inappropriate production can support the development of fungus, causing oil crops to suffer from mycotoxin contamination, which in turn migrates to the resulting oil, de-oiled cake and meals during the oil processing. Related research which supports the development of multi-mycotoxin prevention programs has resulted in satisfactory mitigation effects, mainly in the pre-harvest stage. Nevertheless, preventive actions are unlikely to avoid the occurrence of mycotoxins completely, so removal strategies may still be necessary to protect consumers. Elimination of mycotoxin has been achieved broadly through the physical, biological, or chemical course. In view of the steadily increasing volume of scientific literature regarding mycotoxins, there is a need for ongoing integrated knowledge systems. This work revisited the knowledge of mycotoxins affecting oilseeds, food oils, cake, and meals, focusing more on their varieties, toxicity, and preventive strategies, including the methods adopted in the decontamination, which supplement the available information.

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.

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.

Manufacture of a Potential Antifungal Ingredient Using Lactic Acid Bacteria from Dry-Cured Sausages

The growing interest in functional foods has fueled the hunt for novel lactic acid bacteria (LAB) found in natural sources such as fermented foods. Thus, the aims of this study were to isolate, identify, characterize, and quantify LAB’s antifungal activity and formulate an ingredient for meat product applications. The overlay method performed a logical initial screening by assessing isolated bacteria’s antifungal activity in vitro. Next, the antifungal activity of the fermented bacteria-free supernatants (BFS) was evaluated by agar diffusion assay against six toxigenic fungi. Subsequently, the antifungal activity of the most antifungal BFS was quantified using the microdilution method in 96-well microplates. The meat broth that showed higher antifungal activity was selected to elaborate on an ingredient to be applied to meat products. Finally, antifungal compounds such as organic acids, phenolic acids, and volatile organic compounds were identified in the chosen-fermented meat broth. The most promising biological candidates belonged to the Lactiplantibacillus plantarum and Pediococcus pentosaceus. P. pentosaceus C15 distinguished from other bacteria by the production of antifungal compounds such as nonanoic acid and phenyl ethyl alcohol, as well as the higher production of lactic and acetic acid.

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.

Potential Correlation between Microbial Diversity and Volatile Flavor Compounds in Different Types of Korean Dry-Fermented Sausages

The microbial community in fermented sausages plays an important role in determining their quality characteristics. The objective of this study was to investigate the correlation between microbial diversity and volatile compounds in dry-fermented sausages procured from different regions of Korea. Results from metagenomics analysis showed that Lactobacillus and Staphylococcus were the predominant bacterial genera, and Penicillium, Debaryomyces, and Candida were the predominant fungal genera. Twelve volatile compounds were detected using an electronic nose. Leuconostoc exhibited a positive correlation with esters and volatile flavor, whereas Debaryomyces, Aspergillus, Mucor, and Rhodotorula exhibited a negative correlation with methanethiol, thus revealing the involvement of the microorganisms in flavor formation. The results of this study may help in understanding the microbial diversity of dry-fermented sausages in Korea and provide a rationale and quality control guideline through potential correlation with volatile flavor analysis.

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.

Analysis of Key Control Points of Microbial Contamination Risk in Pork Production Processes Using a Quantitative Exposure Assessment Model

Pork is one of the most common foods causing microbial foodborne diseases. Since pork directly enters the market after slaughtering, the control of microbial contamination in the slaughtering processes is the key to ensuring the quality and safety of pork. The contamination level of Escherichia coli, a health-indicator bacterium, can reflect the risk level of potential pathogens. In order to assess the E. coli exposure risk of pork during slaughtering and to identify the key control points, we established an E. coli quantitative exposure assessment model for swine-slaughtering processes in slaughterhouses of different sizes. The model simulation data indicated the E. coli contamination pattern on the surfaces of swine carcasses during slaughtering. The changes in E. coli contamination were analyzed according to the simulation data of each slaughtering process. It was found that the number of E. coli after trimming in big and small slaughterhouses increased to the maximum values for the whole processes, which were 3.63 and 3.52 log₁₀ CFU/100 cm², respectively. The risk contribution of each slaughtering process to the E. coli contamination on the surface of terminal swine carcasses can be determined by correlation analysis. Because the absolute value of correlation coefficient during the trimming process was maximum (0.49), it was regarded as the most important key control point. This result can be further proved via the multilocus sequence typing of E. coli. The dominant sequence type before trimming processes was ST10. ST1434 began to appear in the trimming process and then became the dominant sequence type in the trimming and pre-cooling processes. The model can provide a theoretical basis for microbial hygiene supervision and risk control in swine-slaughtering processes.

Ochratoxin A: Occurrence and recent advances in detoxification

Ochratoxin A (OTA), one of the most important mycotoxins, is mainly produced by fungi in the genera Aspergillus and Penicillium, and commonly found in food and agricultural products. In addition to causing significant economic losses, the occurrence of OTA in foods poses a serious threat to human health. Therefore, it is very important to develop approaches to control or detoxify OTA contamination and thus ensure food safety. In this paper, we review the source and occurrence of OTA in food and agricultural products and the latest achievements in the removal and detoxification of OTA using physical, chemical, and biological methods, with specific attention to influencing factors and mechanisms related to the biodetoxification of OTA. Moreover, the advantages and disadvantages of these methods and their potential application prospect were also discussed.

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.

Distribution, toxicity, interactive effects, and detection of ochratoxin and deoxynivalenol in food: A review

Mycotoxins are secondary metabolites of fungi that cause severe damage to agricultural products and food in the food supply chain. These detrimental pollutants have been directly linked with poor socioeconomic patterns and human health issues. Among the natural micropollutants, ochratoxin A (OTA) and deoxynivalenol (DON) are widely distributed in food materials. The primary occurrence of these mycotoxins is reported in almost all cereal grains and fresh agro-products. Both mycotoxins have shown harmful effects, such as nephrotoxic, hepatotoxic, and genotoxic effects, in humans due to their complex structural formation during the degradation/acetylation reaction. In addition, improper preharvest, harvest, and postharvest handling tend to lead to the formation of OTA and DON in various food commodities, which allows different harmful fungicides in practice. Therefore, this review provides more insight into the distribution and toxicity of OTA/DON in the food matrix and human health. Furthermore, the interactive effects of OTA/DON with co-contaminated organic and inorganic compounds are discussed. Finally, international regulation and mitigation strategies for detoxication are critically evaluated to meet food safety and good agriculture practices.

Microbial Ecology of French Dry Fermented Sausages and Mycotoxin Risk Evaluation During Storage

Dry fermented sausages are produced worldwide by well-controlled fermentation processes involving complex microbiota including many bacterial and fungal species with key technological roles. However, to date, fungal diversity on sausage casings during storage has not been fully described. In this context, we studied the microbial communities from dry fermented sausages naturally colonized or voluntarily surface inoculated with molds during storage using both culture-dependent and metabarcoding methods. Staphylococci and lactic acid bacteria largely dominated in samples, although some halotolerant genera (e.g., Halomonas, Tetragenococcus, and Celerinatantimonas spp.) were also frequently observed. Fungal populations varied from 7.2 to 9.8 log TFU/cm² sausage casing during storage, suggesting relatively low count variability among products. Fungal diversity identified on voluntarily inoculated casings was lower (dominated by Penicillium nalgiovense and Debaryomyces hansenii) than naturally environment-inoculated fermented sausages (colonized by P. nalgiovense, Penicillium nordicum, and other Penicillium spp. and sporadically by Scopulariopsis sp., D. hansenii, and Candida zeylanoïdes). P. nalgiovense and D. hansenii were systematically identified, highlighting their key technological role. The mycotoxin risk was then evaluated, and in situ mycotoxin production of selected mold isolates was determined during pilot-scale sausage productions. Among the identified fungal species, P. nalgiovense was confirmed not to produce mycotoxins. However, some P. nordicum, Penicillium chrysogenum, Penicillium bialowienzense, Penicillium brevicompactum, and Penicillium citreonigrum isolates produced one or more mycotoxins in vitro. P. nordicum also produced ochratoxin A during pilot-scale sausage productions using “worst-case” conditions in the absence of biotic competition. These data provide new knowledge on fermented sausage microbiota and the potential mycotoxin risk during storage.

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.

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.

Development of a Methodology for Estimating the Ergosterol in Meat Product-Borne Toxigenic Moulds to Evaluate Antifungal Agents

Antifungal agents are commonly used in the meat industry to prevent the growth of unwanted moulds, such as toxigenic ones, on dry-cured meat products. For enhancing the application of antifungals, their mode of action must be evaluated. Their effect on the mould ergosterol content is one of the most studied ones, since it is the target site of some commercialised antifungals or of those that are in development. The aim of this study was to develop a methodology for determining how the antifungal agents used in the meat industry work. A method for analysing ergosterol was firstly developed using high-performance liquid chromatography with fluorescence detection coupled to a diode array detector (HPLC-FLD/DAD). The chromatographically optimised conditions (gradient and mobile phases) allowed us to reduce the time per analysis with respect to previously published methods up to 22 min. Withing the six checked extraction methods, method 5, showing the best mean recovery values (99.51%), the shortest retention time (15.8 min), and the lowest standard deviation values (9.92) and working temperature (60 °C), was selected. The limit of detection and limit of quantification were 0.03 and 0.1 µg/mL, respectively. All the validation parameters corroborated the method's suitability. Finally, its feasibility for evaluating the effect of a commercial antifungal preparation (AP) and different herbs that are frequently added to meat products on the ergosterol content of several toxigenic moulds was studied. Differences at the strain level were obtained in the presence of AP. Moreover, the addition of herbs significantly reduced the ergosterol content in Penicillium nordicum up to 83.91%. The developed methodology is thus suitable for screening the antifungals' role in altering mould ergosterol biosynthesis before their application in real meat products.

Application of new technologies in decontamination of mycotoxins in cereal grains: Challenges, and perspectives

Emerging decontamination technologies have been attracted considerable attention to address the consumers' demand for high quality and safe food products. As one of the important foods in the human diet, cereals are usually stored for long periods, resulting in an increased risk of contamination by different hazards. Mycotoxins comprise one of the significant contaminants of cereals that lead to enormous economic losses to the industry and threats to human health. While prevention is the primary approach towards reducing human exposure to mycotoxins, decontamination methods have also been developed as complementary measures. However, some conventional methods (chemical treatments) do not fulfill industries' expectations due to limitations like safety, efficiency, and the destruction of food quality attributes. In this regard, novel techniques have been proposed to food to comply with the industry's demand and overcome conventional methods' limitations. Novel techniques have different efficiencies for removing or reducing mycotoxins depending on processing conditions, type of mycotoxin, and the food matrix. Therefore, this review provides an overview of novel mycotoxin decontamination technologies such as cold plasma, irradiation, and pulse light, which can be efficient for reducing mycotoxins with minimum adverse effects on the quality and nutritional properties of produce.

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.

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.

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.

Modelling Fungal Growth, Mycotoxin Production and Release in Grana Cheese

No information is available in the literature about the influence of temperature (T) on Penicillium and Aspergillus spp. growth and mycotoxin production on cheese rinds. The aim of this work was to: (i) study fungal ecology on cheese in terms of T requirements, focusing on the partitioning of mycotoxins between the rind and mycelium; and (ii) validate predictive models previously developed by in vitro trials. Grana cheese rind blocks were inoculated with A. versicolor, P. crustosum, P. nordicum, P. roqueforti, and P. verrucosum, incubated at different T regimes (10–30 °C, step 5 °C) and after 14 days the production of mycotoxins (ochratoxin A (OTA); sterigmatocystin (STC); roquefortine C (ROQ-C), mycophenolic acid (MPA), Pr toxin (PR-Tox), citrinin (CIT), cyclopiazonic acid (CPA)) was quantified. All the fungi grew optimally around 15–25 °C and produced the expected mycotoxins (except MPA, Pr-Tox, and CIT). The majority of the mycotoxins produced remained in the mycelium (~90%) in three out of five fungal species (P. crustosum, P. nordicum, and P. roqueforti); the opposite occurred for A. versicolor and P. verrucosum with 71% and 58% of STC and OTA detected in cheese rind, respectively. Available predictive models fitted fungal growth on the cheese rind well, but validation was not possible for mycotoxins because they were produced in a very narrow T range.

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.

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.

Effect of Spanish smoked paprika "Pimentón de La Vera" on control of ochratoxin A and aflatoxins production on a dry-cured meat model system

Environmental conditions during ripening of dry-cured meat products favour growth of fungal population on their surface. Some of these moulds can produce mycotoxins. Paprika is one of the ingredients usually used in the formulation of raw-cured sausages, and its addition could influence the growth and production of mycotoxins of the moulds present in these products. In this work the effect of Spanish smoked paprika "Pimentón de la Vera" on growth of Aspergillus parasiticus and Penicillium nordicum and production of aflatoxins B₁ (AFB₁), G₁ (AFG₁) and ochratoxin A (OTA) respectively, was evaluated. Moulds were grown in a culture medium made from lyophilized fresh pork meat added with 4% salt and different concentrations of Spanish smoked paprika (1, 2 and 3%) at several water activity values (0.98, 0.94 and 0.87) and temperature (20-25 °C), to simulate conditions usually found during ripening of dry-cured meat products. Mould growth was evaluated by measuring the diameter of the colony every 24 h, and the production of mycotoxins by UHPLC-MS/MS every 2 days, during 10 days of incubation. Addition of paprika favours growth of the two mould species tested. However, the synthesis of mycotoxins was reduced at 0.94 and 0.98 a_w when at least a 2% of paprika was added. Therefore, the addition of Spanish smoked paprika at 2-3% in the formulations may help to minimize AFs and OTA production in dry-cured meat products such as loins or "chorizo" sausages.