Novel strategies for degradation of aflatoxins in food and feed: A review

Epigallocatechin Gallate and Glutathione Attenuate Aflatoxin B1-Induced Acute Liver Injury in Ducklings via Mitochondria-Mediated Apoptosis and the Nrf2 Signalling Pathway

Aflatoxin B1 (AFB1) exists widely in feed and food with severe hazards, posing a serious threat to human and animal health. Epigallocatechin gallate (EGCG) and glutathione (GSH) have been reported as having anti-oxidative and other functions. The present study aimed to investigate the detoxification effect of EGCG and GSH alone or in combination on AFB1 exposure in ducklings. Fifty one-day-old male ducklings were randomly assigned into five experimental groups (n = 10): 1. Control (CTR); 2. 0.3 mg/kg BW AFB1 (AFB1); 3. 0.3 mg/kg BW AFB1 + 100 mg/kg BW EGCG (AFB1 + EGCG); 4. 0.3 mg/kg BW AFB1 + 30 mg/kg BW GSH (AFB1 + GSH); 5. 0.3 mg/kg BW AFB1 + 100 mg/kg BW EGCG + 30 mg/kg BW GSH (AFB1 + EGCG + GSH). The experiment lasted for seven days. Compared with the CTR group, AFB1 reduced growth performance, total serum protein and albumin content, increased serum enzyme activity (alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, and γ-glutamyl transpeptidase), and caused pathological damage to the ducklings' livers. AFB1 exposure increased malondialdehyde content and decreased superoxide dismutase, total antioxidant capacity, catalase, glutathione peroxidase activities, and glutathione content in the liver. EGCG and GSH alone or in combination mitigated these adverse effects. Meanwhile, EGCG and GSH attenuate apoptosis of hepatocytes, and regulated AFB1-induced changes in the abundance of genes contained in the Keap1/Nrf2 signalling and apoptotic pathways. Collectively, these results suggest that EGCG and GSH alleviate the hepatocyte injury induced by AFB1 by inhibiting oxidative stress and attenuating excessive mitochondria-mediated apoptosis.

Stability Evaluation of Aflatoxin B1 Solution Certified Reference Material via Ultra-High Performance Liquid Chromatography Coupled with High-Resolution Mass Spectrometry

Aflatoxin B₁ (AFB₁) solution certified reference materials (CRMs) have been widely utilized in the measurements of AFB₁ contaminations in foods and agricultural products. It is of great importance to evaluate the stability of AFB₁ solution CRMs in different matrices for their practical applications. In this study, the stability of AFB₁ solution CRM was investigated and its degradation products under various conditions were elucidated using ultra-high performance liquid chromatography coupled with high-resolution mass spectrometry for the first time. Exposure to high temperatures and UV light irradiation accelerated the degradation of AFB₁ solution significantly, and the degradation products were largely dependent on the solvents. Two degradation pathways were proposed based on the degradation products. The addition reaction, oxidation reaction, and modification of the methoxy group are the major processes involved in the degradation of the AFB₁ solution. The results of this study indicate that the property value of the acetonitrile solution of AFB₁ can be well retained when it is stored at temperatures lower than 60 °C, and the exposure to UV light irradiation is avoided.

Single, Subsequent, or Simultaneous Treatments to Mitigate Mycotoxins in Solid Foods and Feeds: A Critical Review

Mycotoxins in solid foods and feeds jeopardize the public health of humans and animals and cause food security issues. The inefficacy of most preventive measures to control the production of fungi in foods and feeds during the pre-harvest and post-harvest stages incited interest in the mitigation of these mycotoxins that can be conducted by the application of various chemical, physical, and/or biological treatments. These treatments are implemented separately or through a combination of two or more treatments simultaneously or subsequently. The reduction rates of the methods differ greatly, as do their effect on the organoleptic attributes, nutritional quality, and the environment. This critical review aims at summarizing the latest studies related to the mitigation of mycotoxins in solid foods and feeds. It discusses and evaluates the single and combined mycotoxin reduction treatments, compares their efficiency, elaborates on their advantages and disadvantages, and sheds light on the treated foods or feeds, as well as on their environmental impact.

Kinetics of microbial and photochemical degradation of aflatoxin B1 in a sandy loam and clay soil

In a 28-days experiment, we investigated the dissipation of aflatoxin B1 (AFB1) (0.5–500 \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\upmu }\text {g}\,\text {kg}^{-1}$$\end{document}μgkg-1) by microbial (MD) and photodegradation (PD) in two contrasting soils (sandy loam and clay). Sterile incubation in darkness served as control (C). AFB1 was degraded in all scenarios according to simple first-order kinetics with 50% dissipation times of 20–32 (PD), 19–48 (MD), and 56–65 days (C), respectively. Dissipation rates were significantly lower (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\text {p}<0.001$$\end{document}p<0.001) in the clay soil than in the sandy loam soil, likely due to photoquenching and strong binding of AFB1 by clay minerals and humic substances. In the sandy loam, dissipation rate of MD decreased in function of initial AFB1 concentration, probably due to toxic effects on degrading microbes. In contrast, in the clay soil the dissipation rate increased with increasing concentration up to 250 \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\upmu \text {g}\,\text {kg}^{-1}$$\end{document}μgkg-1, followed by a sharp decrease at 500 \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\upmu \text {g}\,\text {kg}^{-1}$$\end{document}μgkg-1, indicating an effect of soil texture on the bioavailability of AFB1 to soil microbes. AFB2a was identified as a transformation product in all scenarios. These results confirm the function of soil for AFB1 degradation, which is modulated by abiotic and biotic processes, soil characteristics and initial AFB1 concentration.

The influence of ultraviolet radiation on aflatoxin producing Aspergillus species' isolated from Iranian rice

Cereal grains are a favorable habitat for aflatoxin- producing fungus to develop. the current investigation was carried out to evaluate the quantity and kind of contaminated imported grains and rice generated in the province of Shiraz, Iran. A total of 60 random rice samples were taken from paddy fields in October and November 2020. Aspergillus genera were detected using PCR. HPLC was used to determine the quantity and type of aflatoxin and mycotoxins in samples collected. Irradiation studies were carried out utilizing a collimated beam system with wavelengths ranging from 200 to 360 nm. The quality of rice was assessed using UV light therapy on some of the changed factors, such as amylose content, aroma, and brightness [P < 0.05]. Aspergillus genera were found in 33.3% [20 samples of 60] of rice samples after morphological and molecular analysis of the ITS gene. According to the sequencing experiment, 12 strains [60%] were identified as Aspergillus flavus, whereas 8 strains [40%] were identified as Aspergillus parasiticus. Ver-1 and afl-R genes were positive in 12/12 [100%] Aspergillus flavus and 87.5% in Aspergillus parasiticus. According to the HPLC findings, three Aspergillus parasiticus strains [37.5%] were able to create all four types of aflatoxins, and aflatoxins B1, B2, G1, G2 were produced by 16.6% of Aspergillus flavus strains. Aflatoxin-1 (AFG1) was lowered to 35.1, 48.2, 59.9, and 65.2%, significantly, at doses of 1.22, 2.44, 3.66, and 4.88 Jcm-2 [P < 0.01]. Furthermore, at doses of 1.22, 2.44, 3.66, and 4.88 Jcm-2, AFB2 and AFG2 was shown to be reduced by 13.1%, 11.7%, 30.3%, and 28.9%. [P < 0.05]. At a maximum dose of 4.88 Jcm-2, AFB1 was shown to be extremely susceptible to UV irradiation, with a > 70% decrease seen [P < 0.001]. Our findings imply that UV irradiation with lower energy and lower danger can help minimize aflatoxin contamination in food.

Antimicrobial action of phenolic acids combined with violet 405-nm light for disinfecting pathogenic and spoilage fungi

The aim of this study is to investigate the fungicidal spectrum of six phenolic-cinnamic and -benzoic acid derivatives using four fungi, Aspergillus niger, Cladosporium cladosporioides, Trichophyton mentagrophytes and Candida albicans, in a photocombination system with violet 405-nm light. This is the first study to examine the fungicidal mechanism involving oxidative damage using the conidium of A. niger, as well as an assessment of cellular function and chemical characteristics. The results of the screening assay indicated that ferulic acid (FA) and vanillic acid (VA), which possess 4-hydroxyl and 3-methoxy groups in their phenolic acid structures, produced synergistic activity with 405-nm light irradiation. FA and VA (5.0 mM) significantly decreased the viability of A. niger by 2.4 to 2.6-logs under 90-min irradiation. The synergistic effects were attenuated by the addition of the radical scavenger dimethyl sulfoxide. Generation of reactive oxygen species (ROS), such as hydrogen peroxide and hydroxyl radicals, were confirmed in the phenolic acid solutions tested after irradiation with colorimetric and electron spin resonance analyses. Adsorption of FA and VA to conidia was greater than other tested phenolic acids, and produced 1.55- and 1.85-fold elevation of intracellular ROS levels, as determined using an oxidant-sensitive probe with flow cytometry analysis. However, cell wall or membrane damage was not the main mechanism by which the combination-induced fungal death was mediated. Intracellular ATP was drastically diminished (5% of control levels) following combined treatment with FA and light exposure, even under a condition that produced negligible decreases in viability, thereby resulting in pronounced growth delay. These results suggest that the first stage in the photofungicidal mechanism is oxidative damage to mitochondria or the cellular catabolism system associated with ATP synthesis, which is a result of the photoreaction of phenolic acids adsorbed and internalized by conidia. This photo-technology in combination with food-grade phenolic acids can aid in developing alternative approaches for disinfection of pathogenic and spoilage fungi in the fields of agriculture, food processing and medical care.

Approaches to Inactivating Aflatoxins-A Review and Challenges

According to the World Health Organization, the contamination of crops with aflatoxins poses a significant economic burden, estimated to affect 25% of global food crops. In the event that the contaminated food is processed, aflatoxins enter the general food supply and can cause serious diseases. Aflatoxins are distributed unevenly in food or feedstock, making eradicating them both a scientific and a technological challenge. Cooking, freezing, or pressurizing have little effect on aflatoxins. While chemical methods degrade toxins on the surface of contaminated food, the destruction inside entails a slow process. Physical techniques, such as irradiation with ultraviolet photons, pulses of extensive white radiation, and gaseous plasma, are promising; yet, the exact mechanisms concerning how these techniques degrade aflatoxins require further study. Correlations between the efficiency of such degradation and the processing parameters used by various authors are presented in this review. The lack of appropriate guidance while interpreting the observed results is a huge scientific challenge.

Occurrence of Aflatoxin B1, deoxynivalenol and zearalenone in feeds in China during 2018-2020

BACKGROUND

The current study was conducted to investigate the individual and combined occurrence of aflatoxin B1 (AFB1), deoxynivalenol (DON) and zearalenone (ZEN) in feeds from various Provinces of China during 2018 to 2020. A total of 3,507 feed samples, including 2,090 feed ingredients and 1,417 complete feed samples, were collected from different areas of China for mycotoxins analysis.

RESULTS

The individual contamination of AFB1, DON and ZEN were present in more than 81.9%, 96.4% and 96.9% of feed samples, respectively, with average concentration ranges of AFB1 between 1.2-27.4 μg/kg, DON between 458.0-1,925.4 μg/kg and ZEN between 48.1-326.8 μg/kg. Notably, 0.9%, 0.5% and 0.1% of feed ingredients, and 1.2-12.8%, 0.9-2.9% and 0-8.9% of complete feeds for pigs, poultry and ruminants with AFB1, ZEN and DON that exceeded China's safety standards, respectively. Moreover, more than 81.5% of feed ingredients and 95.7% of complete feeds were co-contaminated with various combinations of these mycotoxins.

CONCLUSION

This study indicates that the feeds in China were universally contaminated with AFB1, DON and ZEN during the past 3 years. These findings highlight the significance of monitoring mycotoxin contaminant levels in the domestic animal feed, and the importance of carrying out feed administration and remediation strategies for mycotoxin control.

Recombinant Expression of Trametes versicolor Aflatoxin B1-Degrading Enzyme (TV-AFB1D) in Engineering Pichia pastoris GS115 and Application in AFB1 Degradation in AFB1-Contaminated Peanuts

Aflatoxins seriously threaten the health of humans and animals due to their potential carcinogenic properties. Enzymatic degradation approach is an effective and environmentally friendly alternative that involves changing the structure of aflatoxins. In this study, Trametes versicolor aflatoxin B₁-degrading enzyme gene (TV-AFB₁D) was integrated into the genome of Pichia pastoris GS115 by homologous recombination approach. The recombinant TV-AFB₁D was expressed in engineering P. pastoris with a size of approximately 77 kDa under the induction of methanol. The maximum activity of TV-AFB₁D reached 17.5 U/mL after the induction of 0.8% ethanol (v/v) for 84 h at 28 °C. The AFB₁ proportion of 75.9% was degraded using AFB₁ standard sample after catalysis for 12 h. In addition, the AFB₁ proportion was 48.5% using AFB₁-contaminated peanuts after the catalysis for 18 h at 34 °C. The recombinant TV-AFB₁D would have good practical application value in AFB₁ degradation in food crops. This study provides an alternative degrading enzyme for the degradation of AFB₁ in aflatoxin-contaminated grain and feed via enzymatic degradation approach.