The development of LC-MS/MS method of determination of cyclopiazonic acid in dry-fermented meat products

Upconversion-Linked Immunosorbent Assay for the Biomimetic Detection of the Mycotoxin Cyclopiazonic Acid

The neurotoxin α-cyclopiazonic acid (CPA) is an emerging mycotoxin produced as a secondary metabolite by several fungi species (i.e., Penicillium spp. and Aspergillus spp.). CPA commonly contaminates maize, crops, cheese, and wine. In this work, CPA detection in foodstuff was accomplished by the innovative integration of two strategies: upconversion nanoparticles (UCNPs) and epitope-mimicking peptides, to develop a competitive upconversion-linked immunosorbent assay (ULISA). We have applied UCNPs (type NaYF4:Yb3+, Er3+) as background-free optical labels due to their anti-Stokes shift with excitation in the near-infrared region and emission in the ultraviolet-visible region. Moreover, a CPA epitope-mimicking cyclic peptide (A2) was used as a substitute for the toxin-conjugates traditionally applied to competitive assays. UCNPs were decorated with an anti-CPA fragment antigen-binding antibody (UCNP-Fab), and CPA detection was achieved through competition with a biotinylated CPA epitope-mimicking cyclic peptide (A2-biotin, ACNWWDLTLC-GGGSK (Biotin)-NH2), anchored to a streptavidin-coated microtiter plate, for antibody binding. The ULISA platform offers ultrasensitive detection of CPA (limit of detection of 1.3 pg mL-1 and IC50 value of 15 pg mL-1), and no cross-reactivity was observed with other coproduced mycotoxins. These results substantially outperformed the analytical features of conventional heterogeneous immunoassays based on enzymatic detection. Additionally, the use of advanced computational tools, such as MOE and Alphafold AI, proved advantageous in elucidating the molecular interactions between the antibody and the epitope, providing insights that enhance the rational design of immunoassays. The proposed ULISA was applied to detect CPA in spiked maize samples, and the results were validated by high-performance liquid chromatography coupled to a tandem mass spectrometry detector (HPLC-MS/MS).

One-Pot Preparation of Mixed-Mode Reversed-Phase Anion-Exchange Silica Sorbent and its Application in the Detection of Cyclopiazonic Acid in Feeds and Agricultural Products

A novel co-bonded octyl and pyridine silica (OPS) sorbent was prepared and applied for the solid phase extraction (SPE) of cyclopiazonic acid (CPA, a type of mycotoxin) in feed and agricultural products for the first time. A simple mixed-ligand one-pot reaction strategy was employed for OPS sorbent preparation. Nitrogen adsorption-desorption measurements, elemental analysis (EI), thermal gravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FT-IR) analysis demonstrated the successful immobilization of octyl and quaternary ammonium groups onto the surface of silica gel. The large specific surface area, high-density functional groups, and mixed-mode anion-exchange characteristics of these silica particles made them the ideal material for the efficient extraction of CPA. Additionally, the OPS sorbents displayed excellent batch-to-batch reproducibility, satisfactory reusability, and low cost. The SPE parameters were optimized to explore the ionic and hydrophobic interactions between CPA and the functional groups, and the ultra-high performance liquid chromatography coupled with triple-quadrupole tandem mass spectrometry (UPLC-MS/MS) parameters were optimized to obtain a desirable extraction efficiency and high sensitivity to CPA. Meanwhile, the OPS sorbent presented a satisfactory extraction selectivity and low matrix effect. Under the optimized conditions, our developed CPA detection method was used to determine CPA level in rice, wheat flour, corn flour, peanut, and feed samples, exhibiting a lower detection limit, better linearity, higher sensitivity, and satisfactory extraction recovery rate than previously reported methods. Therefore, our method can be preferentially used as a method for the detection of CPA in agricultural products and feeds.

Climate Change and Mycotoxins Trends in Serbia and Croatia: A 15-Year Review

This review examines the 15-year presence of mycotoxins in food from Serbia and Croatia to provide a comprehensive overview of trends. Encompassing the timeframe from 2009 to 2023, this study integrates data from both countries and investigates climate change patterns. The results from Serbia focus primarily on maize and milk and show a strong dependence of contamination on weather conditions. However, there is limited data on mycotoxins in cereals other than maize, as well as in other food categories. Conversely, Croatia has a broader spectrum of studies, with significant attention given to milk and maize, along with more research on other cereals, meat, and meat products compared to Serbia. Over the investigated 15-year period, both Serbia and Croatia have experienced notable shifts in climate, including fluctuations in temperature, precipitation, and humidity levels. These changes have significantly influenced agriculture, consequently affecting the occurrence of mycotoxins in various food products. The results summarized in this 15-year review indicate the urgent need for further research and action to address mycotoxins contamination in Serbian and Croatian food supply chains. This urgency is further emphasized by the changing climatic conditions and their potential to exacerbate public health and food safety risks associated with mycotoxins.

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.

Homogeneous immunoassay for cyclopiazonic acid based upon mimotopes and upconversion-resonance energy transfer

Strains of Penicillium spp. are used for fungi-ripened cheeses and Aspergillus spp. routinely contaminate maize and other crops. Some of these strains can produce toxic secondary metabolites (mycotoxins), including the neurotoxin α-cyclopiazonic acid (CPA). In this work, we developed a homogeneous upconversion-resonance energy transfer (UC-RET) immunoassay for the detection of CPA using a novel epitope mimicking peptide, or mimotope, selected by phage display. CPA-specific antibody was used to isolate mimotopes from a cyclic 7-mer peptide library in consecutive selection rounds. Enrichment of antibody binding phages was achieved, and the analysis of individual phage clones revealed four different mimotope peptide sequences. The mimotope sequence, ACNWWDLTLC, performed best in phage-based immunoassays, surface plasmon resonance binding analyses, and UC-RET-based immunoassays. To develop a homogeneous assay, upconversion nanoparticles (UCNP, type NaYF₄:Yb³⁺, Er³⁺) were used as energy donors and coated with streptavidin to anchor the synthetic biotinylated mimotope. Alexa Fluor 555, used as an energy acceptor, was conjugated to the anti-CPA antibody fragment. The homogeneous single-step immunoassay could detect CPA in just 5 min and enabled a limit of detection (LOD) of 30 pg mL^-1 (1.5 μg kg^-1) and an IC₅₀ value of 0.36 ng mL^-1. No significant cross-reactivity was observed with other co-produced mycotoxins. Finally, we applied the novel method for the detection of CPA in spiked maize samples using high-performance liquid chromatography coupled to a diode array detector (HPLC-DAD) as a reference method.

The Occurrence of Five Unregulated Mycotoxins Most Important for Traditional Dry-Cured Meat Products

This study investigated the occurrence of 5 unregulated mycotoxins in a total of 250 traditional dry-cured meat products sampled in 2020 and 2021 in five Croatian regions (eastern, northern, central, western, and southern). Aflatoxin B₁ (AFB₁), ochratoxin A (OTA), sterigmatocystin (STC), citrinin (CIT), and cyclopiazonic acid (CPA) concentrations were related to the geographical region of the product’s origin and to local weather. The results revealed the contamination of 27% of samples, namely, STC in 4% of samples in concentrations of up to 3.93 µg/kg, OTA in 10% of samples in concentrations of up to 4.81 µg/kg, and CPA in 13% of samples in concentrations of up to 335.5 µg/kg. No AFB₁ or CIT contamination was seen. Although no statistically significant differences in concentrations of individual mycotoxins across the production regions were found, differences in mycotoxin occurrence were revealed. The eastern and western regions, with moderate climate, delivered the largest number of contaminated samples, while the southern region, often compared with subtropics, delivered the smallest, so that the determined mycotoxins were probably mainly produced by the Penicillium rather than the Aspergillus species. Due to the interaction of various factors that may affect mycotoxin biosynthesis during production, the detected concentrations cannot be related solely to the weather.

'Kodo poisoning': cause, science and management

Many mycotoxigenic fungi infect the food crops and affect the quality of the produce due to production of mycotoxins. Kodo millet is one of the important minor millets cultivated in India, mostly confined to marginal lands and tribal regions but has high yield potential under good management. The grains are nutritious and have anti-oxidant properties besides having many medicinal properties. However, the consumption is often hindered by the condition called 'kodo poisoning' resulting from fungal contamination producing cyclopiazonic acid, a toxic fungal secondary metabolite. An attempt has been made here to review the limited information available on kodo poisoning, its causes and effects, and proposed management practices by which the contamination can be checked. Further research efforts are essential for identifying sources of natural resistance to fungal metabolite, induction of host resistance through antimicrobial compounds or microbial antagonism to the pathogens to achieve cleaner grains from this crop even under high humid and rainy conditions. By effective adoption of both pre- and post-harvest management the kodo millet grains can be made safe for human consumption and can be popularized as a nutritious grain.

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

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

Pathways of Mycotoxin Occurrence in Meat Products: A Review

Documented cases of mycotoxin occurrence in meat products call for further research into potential contamination sources, especially given an ever more increasing consumption of these nutritionally rich products. These foodstuffs can be contaminated with mycotoxins through three pathways: contaminated spices and other raw materials, mycotoxin-producing moulds present on the surface of dry-cured meat products, and carry-over effect from farm animals exposed to contaminated feed. In order to establish meat products’ mycotoxin contamination more precisely, the concentrations of all mycotoxins of relevance for these products should be determined. This manuscript reviews data on major mycotoxins present in different types of meat products, and discusses the contamination pathways, contamination levels and control & preventative measures.

Mycobiota and Mycotoxin Contamination of Traditional and Industrial Dry-Fermented Sausage Kulen

The aim of this study was to identify and compare surface mycobiota of traditional and industrial Croatian dry-fermented sausage Kulen, especially toxicogenic species, and to detect contamination with mycotoxins recognized as the most important for meat products. Identification of mould species was performed by sequence analysis of beta- tubulin and calmodulin gene, while the determination of mycotoxins aflatoxin B₁ (AFB₁), ochratoxin A (OTA), and cyclopiazonic acid (CPA) was carried out using the LC-MS/MS (liquid chromatography-tandem mass spectrometry) method. The results showed a significantly higher number of mould isolates and greater species (including of those mycotoxigenic) diversity in traditional Kulen samples in comparison with the industrial ones. P. commune, as a potential CPA-producer, was the most represented in traditional Kulen (19.0%), followed by P. solitum (16.6%), which was the most represented in industrial Kulen samples (23.8%). The results also showed that 69% of the traditional sausage samples were contaminated with either CPA or OTA in concentrations of up to 13.35 µg/kg and 6.95 µg/kg, respectively, while in the industrial samples only OTA was detected (in a single sample in the concentration of 0.42 µg/kg). Mycotoxin AFB₁ and its producers were not detected in any of the analysed samples (<LOD).