Aflatoxins and food pathogens: impact of biologically active aflatoxins and their control strategies

Globally disease outbreaks as a result of the consumption of contaminated food and feedstuffs are a regular primary problem. The foremost elements contributing to contamination are microorganisms, particularly fungi, which produce low‐molecular weight secondary metabolites, with demonstrated toxic properties that are referred to as mycotoxins. Aflatoxins contaminate agricultural commodities and may cause sickness or fatality in humans and animals. Moreover, poor conditions of storage and a deficiency in regulatory measures in food quality control aggravate the main issue. For that reason, mycotoxin‐related illness of nutrition represents a major health hazard for local populations. Government policies should make regulations aiming to avoid the entry of aflatoxins into food stuffs. For consumer safety, control and management strategies should be developed and implemented by regulatory authorities. There is the need for attention from farmers, scientists, government and collaborative minds throughout the country to ensure aflatoxin‐free food. The present review is informative not only for health‐conscious consumers, but also for relevant authorities with respect to paving the way for future research aiming to fill the existing gaps in our knowledge with regard to mycotoxins and food security. © 2016 Society of Chemical Industry     

Mycotoxin Contamination of the Food Supply Chain - Implications for One Health Programme

Mycotoxins are a group of naturally occurring toxic chemical substances, produced by different fungal species, which can cause illness or even death due to their toxigenic, carcinogenic, mutagenic and teratogenic effects. Though more than 400 mycotoxins are known to have toxic effects on human when ingested along with contaminated food, mycotoxins like aflatoxins, ochratoxins, zeralenone, trichothecenes and fumonisins are the major mycotoxins influencing the public health and agriculture. Due to the global nature of the food supply and advances in analytical capabilities, mycotoxin contamination will continue to be an area of concern for regulatory agencies, the food industry, and consumers.     

Mycotoxin problem in Africa: current status, implications to food safety and health and possible management strategies

Mycotoxins are toxic secondary metabolites of fungal origin and contaminate agricultural commodities before or under post-harvest conditions. They are mainly produced by fungi in the Aspergillus, Penicillium and Fusarium genera. When ingested, inhaled or absorbed through the skin, mycotoxins will cause lowered performance, sickness or death on humans and animals. Factors that contribute to mycotoxin contamination of food and feed in Africa include environmental, socio-economic and food production. Environmental conditions especially high humidity and temperatures favour fungal proliferation resulting in contamination of food and feed. The socio-economic status of majority of inhabitants of sub-Saharan Africa predisposes them to consumption of mycotoxin contaminated products either directly or at various points in the food chain. The resulting implications include immuno-suppression, impaired growth, various cancers and death depending on the type, period and amount of exposure. A synergistic effect between mycotoxin exposure and some important diseases in the continent such as malaria, kwashiorkor and HIV/AIDS have been suggested. Mycotoxin concerns have grown during the last few decades because of their implications to human and animal health, productivity, economics of their management and trade. This has led to development of maximum tolerated limits for mycotoxins in various countries. Even with the standards in place, the greatest recorded fatal mycotoxin-poisoning outbreak caused by contamination of maize with aflatoxins occurred in Africa in 2004. Pre-harvest practices; time of harvesting; handling of produce during harvesting; moisture levels at harvesting, transportation, marketing and processing; insect damage all contribute to mycotoxin contamination. Possible intervention strategies include good agricultural practices such as early harvesting, proper drying, sanitation, proper storage and insect management among others. Other possible interventions include biological control, chemical control, decontamination, breeding for resistance as well as surveillance and awareness creation. There is need for efficient, cost-effective sampling and analytical methods that can be used for detection analysis of mycotoxins in developing countries.     

Post-harvest control strategies: minimizing mycotoxins in the food chain

Contamination of cereal commodities by moulds and mycotoxins results in dry matter, quality, and nutritional losses and represents a significant hazard to the food chain. Most grain is harvested, dried and then stored on farm or in silos for medium/long term storage. Cereal quality is influenced by a range of interacting abiotic and biotic factors. In the so-called stored grain ecosystem, factors include grain and contaminant mould respiration, insect pests, rodents and the key environmental factors of temperature, water availability and intergranular gas composition, and preservatives which are added to conserve moist grain for animal feed. Thus knowledge of the key critical control points during harvesting, drying and storage stages in the cereal production chain are essential in developing effective prevention strategies post-harvest. Studies show that very small amounts of dry matter loss due to mould activity can be tolerated. With <0.5% dry matter loss visible moulding, mycotoxin contamination and downgrading of lots can occur. The key mycotoxigenic moulds in partially dried grain are Penicillium verrucosum (ochratoxin) in damp cool climates of Northern Europe, and Aspergillus flavus (aflatoxins), A. ochraceus (ochratoxin) and some Fusarium species (fumonisins, trichothecenes) on temperate and tropical cereals. Studies on the ecology of these species has resulted in modelling of germination, growth and mycotoxin minima and prediction of fungal contamination levels which may lead to mycotoxin contamination above the tolerable legislative limits (e.g. for ochratoxin). The effect of modified atmospheres and fumigation with sulphur dioxide and ammonia have been attempted to try and control mould spoilage in storage. Elevated CO2 of >75% are required to ensure that growth of mycotoxigenic moulds does not occur in partially dried grain. Sometimes, preservatives based on aliphatic acids have been used to prevent spoilage and mycotoxin contamination of stored commodities, especially feed. These are predominantly fungistats and attempts have been made to use alternatives such as essential oils and anti-oxidants to prevent growth and mycotoxin accumulation in partially dried grain. Interactions between spoilage and mycotoxigenic fungi and insect pests inevitably occurs in stored grain ecosystems and this can further influence contamination with mycotoxins. Effective post-harvest management of stored commodities requires clear monitoring criteria and effective implementation in relation to abiotic and biotic factors, hygiene and monitoring to ensure that mycotoxin contamination is minimised and that stored grain can proceed through the food chain for processing.     

Naturally occurring phenolic compounds as promising antimycotoxin agents: Where are we now?

Mycotoxins are metabolites produced by molds that contaminate food commodities, are harmful to both humans and animals, as well as cause economic losses. Many countries have set regulatory limits and strict thresholds to control the level of mycotoxins in food and feedstuffs. New technologies and strategies have been developed to inhibit toxigenic fungal invasion and to decontaminate mycotoxins. However, many of these strategies do not sufficiently detoxify mycotoxins and leave residual toxic by-products. This review focuses on the use of phenolic compounds obtained from botanical extracts as promising bioagents to inhibit fungal growth and/or to limit mycotoxin yields. The mechanism of these botanicals, legislation concerning their use, and their safety are also discussed. In addition, recent strategies to overcome stability and solubility constraints of phenolic compounds to be used in food and feed stuffs are also mentioned.     

Advances in Mycotoxin Research: Public Health Perspectives

Aflatoxins, ochratoxins, fumonisins, deoxynivalenol, and zearalenone are of significant public health concern as they can cause serious adverse effects in different organs including the liver, kidney, and immune system in humans. These toxic secondary metabolites are produced by filamentous fungi mainly in the genus Aspergillus, Penicillium, and Fusarium. It is challenging to control the formation of mycotoxins due to the worldwide occurrence of these fungi in food and the environment. In addition to raw agricultural commodities, mycotoxins tend to remain in finished food products as they may not be destroyed by conventional processing techniques. Hence, much of our concern is directed to chronic health effects through long‐term exposure to one or multiple mycotoxins from contaminated foods. Ideally risk assessment requires a comprehensive data, including toxicological and epidemiological studies as well as surveillance and exposure assessment. Setting of regulatory limits for mycotoxins is considered necessary to protect human health from mycotoxin exposure. Although advances in analytical techniques provide basic yet critical tool in regulation as well as all aspects of scientific research, it has been acknowledged that different forms of mycotoxins such as analogs and conjugated mycotoxins may constitute a significant source of dietary exposure. Further studies should be warranted to correlate mycotoxin exposure and human health possibly via identification and validation of suitable biomarkers.     

Mycotoxin contamination of foods in Southern Africa: A 10-year review (2007–2016)

Major staple foods in Southern Africa are prone to mycotoxin contamination, posing health risks to consumers and consequent economic losses. Regional climatic zones favor the growth of one or more main mycotoxin producing fungi, Aspergillus, Fusarium and Penicillium. Aflatoxin contamination is mainly reported in maize, peanuts and their products, fumonisin contamination in maize and maize products and patulin in apple juice. Lack of awareness of occurrence and risks of mycotoxins, poor agricultural practices and undiversified diets predispose populations to dietary mycotoxin exposure. Due to a scarcity of reports in Southern Africa, reviews on mycotoxin contamination of foods in Africa have mainly focused on Central, Eastern and Western Africa. However, over the last decade, a substantial number of reports of dietary mycotoxins in South Africa have been documented, with fewer reports documented in Botswana, Lesotho, Malawi, Mozambique, Zambia and Zimbabwe. Despite the reported high dietary levels of mycotoxins, legislation for their control is absent in most countries in the region. This review presents an up-to-date documentation of the epidemiology of mycotoxins in agricultural food commodities and discusses the implications on public health, current and recommended mitigation strategies, legislation, and challenges of mycotoxin research in Southern Africa.     

Strategies to reduce mycotoxin levels in maize during storage: a review

Maize (Zea mays L.) is one of the main cereals as a source of food, forage and processed products for industry. World production is around 790 million tonnes of maize because as a staple food it provides more than one-third of the calories and proteins in some countries. Stored maize is a man-made ecosystem in which quality and nutritive changes occur because of interactions between physical, chemical and biological factors. Fungal spoilage and mycotoxin contamination are of major concern. Aspergillus and Fusarium species can infect maize pre-harvest, and mycotoxin contamination can increase if storage conditions are poorly managed. Prevention strategies to reduce the impact of mycotoxin in maize food and feed chains are based on using a hazard analysis critical control point systems (HACCP) approach. To reduce or prevent production of mycotoxins, drying should take place soon after harvest and as rapidly as feasible. The critical water content for safe storage corresponds to a water activity (a _w) of about 0.7. Problems in maintaining an adequately low a _w often occur in the tropics where high ambient humidity make the control of commodity moisture difficult. Damage grain is more prone to fungal invasion and, therefore, mycotoxin contamination. It is important to avoid damage before and during drying, and during storage. Drying maize on the cob before shelling is a very good practice. In storage, many insect species attack grain and the moisture that can accumulate from their activities provides ideal conditions for fungal activity. To avoid moisture and fungal contamination, it is essential that the numbers of insects in stored maize should be kept to a minimum. It is possible to control fungal growth in stored commodities by controlled atmospheres, preservatives or natural inhibitors. Studies using antioxidants, essential oils under different conditions of a _w, and temperature and controlled atmospheres have been evaluated as possible strategies for the reduction of fungal growth and mycotoxin (aflatoxins and fumonisins) in stored maize, but the cost of these treatments is likely to remain prohibitive for large-scale use.     

Mycotoxins in Bovine Milk and Dairy Products: A Review

This paper presents a literature review of the occurrence of several mycotoxins in bovine milk and dairy products, because it is the main type of milk produced and marketed worldwide. Mycotoxins are produced by different genera of filamentous fungi and present serious health hazards such as carcinogenicity and mutagenicity. Under favorable growth conditions, toxigenic fungi produce mycotoxins which contaminate the lactating cow's feedstuff. During metabolism, these mycotoxins undergo biotransformation and are secreted in milk. Data show that there is a seasonal trend in the levels of mycotoxins in milk, with these being higher in the cold months probably due to the prolonged storage required for the cattle feeds providing favorable conditions for fungal growth. Good agricultural and storage practices are therefore of fundamental importance in the control of toxigenic species and mycotoxins. Although aflatoxins (especially aflatoxin M₁) are the mycotoxins of greater incidence in milk and dairy products, this review shows that other mycotoxins, such as fumonisin, ochratoxin A, trichothecenes, zearalenone, T‐2 toxin, and deoxynivalenol, can also be found in these products. Given that milk is widely consumed and is a source of nutrients, especially in childhood, a thorough investigation of the occurrence of mycotoxins as well the adoption of measures to minimize their contamination of milk is essential.     

Impact of mycotoxins on human health in developing countries

Adverse human health effects from the consumption of mycotoxins have occurred for many centuries. Although mycotoxin contamination of agricultural products still occurs in the developed world, the application of modern agricultural practices and the presence of a legislatively regulated food processing and marketing system have greatly reduced mycotoxin exposure in these populations. At the mycotoxin contamination levels generally found in food products traded in these market economies, adverse human health effects have largely been overcome. However, in the developing world, where climatic and crop storage conditions are frequently conducive to fungal growth and mycotoxin production, much of the population relies on subsistence farming or on unregulated local markets. The extent to which mycotoxins affect human health is difficult to investigate in countries whose health systems lack capacity and in which resources are limited. Aflatoxin B₁, the toxin on which major resources have been expended, has long been linked to liver cancer, yet its other effects, such as immune suppression and growth faltering previously observed in veterinary studies, are only now being investigated and characterized in human populations. The extent to which factors such as immune suppression contribute to the overall burden of infectious disease is difficult to quantify, but is undoubtedly significant. Thus, food safety remains an important opportunity for addressing current health problems in developing countries.     

Modelling a two-dimensional spatial distribution of mycotoxin concentration in bulk commodities to design effective and efficient sample selection strategies

Mycotoxins in agricultural commodities are a hazard to human and animal health. Their heterogeneous spatial distribution in bulk storage or transport makes it particularly difficult to design effective and efficient sampling plans. There has been considerable emphasis on identifying the different sources of uncertainty associated with mycotoxin concentration estimations, but much less on identifying the effect of the spatial location of the sampling points. This study used a two-dimensional statistical modelling approach to produce detailed information on appropriate sampling strategies for surveillance of mycotoxins in raw food commodities. The emphasis was on deoxynivalenol (DON) and ochratoxin A (OTA) in large lots of grain in storage or bulk transport. The aim was to simulate a range of plausible distributions of mycotoxins in grain from a set of parameters characterising the distributions. For this purpose, a model was developed to generate data sets which were repeatedly sampled to investigate the effect that sampling strategy and the number of incremental samples has on determining the statistical properties of mycotoxin concentration. Results showed that, for most sample sizes, a regular grid proved to be more consistent and accurate in the estimation of the mean concentration of DON, which suggests that regular sampling strategies should be preferred to random sampling, where possible. For both strategies, the accuracy of the estimation of the mean concentration increased significantly up to sample sizes of 40–60 (depending on the simulation). The effect of sample size was small when it exceeded 60 points, which suggests that the maximum sample size required is of this order. Similar conclusions about the sample size apply to OTA, although the difference between regular and random sampling was small and probably negligible for most sample sizes.     

食品中主要真菌毒素生物合成途径研究进展

真菌毒素是真菌重要的次生代谢产物。食品和饲料等农产品在收获、储藏、加工过程中广泛受其污染,造成品质下降、经济损失巨大,并严重威胁人身健康。本文对食品中5种常见真菌毒素(黄曲霉毒素、赭曲霉毒素、伏马菌素、玉米赤霉烯酮和脱氧雪腐镰刀菌烯醇)的生物合成途径分别进行阐释。采用克隆基因的传统分子生物学方法和基因组测序的现代测序技术研究发现,真菌毒素的生物合成基因大多成簇存在,该簇中包含控制合成基因表达的调控基因,并受多种应对外部环境的调控基因所控制。因此本文还结合5种真菌毒素的生物合成基因簇及其基因功能进行综合解析。真菌毒素生物合成的研究将为食品和饲料等农产品的防控、预警以及脱毒提供理论基础和指导方向。     

Food Safety and Increasing Hazard of Mycotoxin Occurrence in Foods and Feeds

The possible hazard of mycotoxin occurrence in foods and feeds and some food-borne mycotoxicoses is reviewed. Management of the risk of mycotoxin contamination using some useful preventive measures against mycotoxin contamination of foods/feeds during pre- and post-harvesting periods is considered. The physical and chemical methods of mycotoxin decontamination of foods/feeds are briefly described. The use of various feed additives as a method for prevention of the adverse effects of mycotoxins is reviewed. The processing of various foods and feeds is considered in a view to possible mycotoxin decontamination. The necessary hygiene control and risk assessment in regard to mycotoxin contamination of foods and feeds in addition to some useful prophylactic measures are briefly described. A short reference is made concerning the most successful methods of veterinary hygiene control in order to prevent a possible entering of some mycotoxins in commercial channels with a view to human health.     

镰孢菌毒素的主要类型及其收获前后的生物防控方法

镰孢菌毒素是镰孢菌属真菌产生的多种有毒性的次级代谢产物的总称,在自然界中分布极为广泛,是常见的污染粮食和饲料的真菌毒素种类,严重威胁人畜健康。近年来镰孢菌毒素污染粮食和饲料的问题日益严重,已成为普遍关注的食品安全和饲料安全热点问题之一。由于农产品收获后的物理、化学的脱毒方法存在着脱毒不彻底、营养成分流失和化学试剂残留对人畜健康的不确定性等问题;因此以生物技术为基础的综合防控镰孢菌及其毒素危害的方法成为了近年来的研究热点之一。本文将重点介绍镰孢菌毒素的主要类型及其对动植物的危害,阐述农产品收获前后生物防治镰孢菌及其毒素危害的方法,并探讨各种防控方法的优缺点以及未来可能的研究方向,以期为镰孢菌毒素综合防控策略的制定提供参考。     

真菌毒素多重检测技术研究进展

真菌毒素分布广、污染重、防控难,从农田到餐桌的全过程均易污染农产品,严重威胁人畜健康和生态环境安全。据统计,农产品真菌毒素的污染中超过75%为多种真菌毒素的混合污染,因此建立高灵敏、高通量的真菌毒素检测技术成为当今食品安全检测领域普遍面临的重大挑战。本文综述了近5 年真菌毒素多重检测技术的研究进展,主要包括高效液相色谱-串联质谱法、免疫层析法、化学比色法、电化学法、化学发光法、荧光法、拉曼光谱法等,分析了这些方法在真菌毒素多重检测中的应用与亟待解决的问题,并对其未来的发展应用前景进行了展望。     

Mycotoxin Contamination of Maize in China

China is a major cereal‐producing country and almost one third of the annual cereal yield is maize. The maize plant and kernel are prone to infection by fungal attack and are most likely to be contaminated with mycotoxins under suitable temperature and humidity conditions, during both the growing and storage period. A number of investigations conducted in China have demonstrated that maize had been infected by fungi and contaminated with mycotoxins to varying degrees. Although most of the maize produced in China is used as feed and raw materials for the chemistry industry, a small amount of maize is consumed directly by humans and the hazards of mycotoxin to humans cannot be ignored. The state of mycotoxin contamination of maize in China is analyzed in this review. Due to unfavorable weather and poor storage conditions, the high incidences of mycotoxin contamination of maize are of great concern to the Chinese. It is imperative for the national and local governments to increase investments on building large‐scale modern warehouses and instructing farmers to grow, harvest, and store maize safely. Meanwhile, due to accumulative toxic effects of mycotoxins, quality control should be enforced to guarantee that animal products are safe for human consumption.     

便携式生物传感器在真菌毒素检测中的应用研究进展

食品在贮藏、运输和加工过程中易受真菌侵染。由真菌代谢所产生的真菌毒素对食品造成了严重的污染，并引发了严峻的食品安全问题。传统的检测方法大多需要大型精密仪器设备、繁琐的操作步骤以及专业技术人员，这在很大程度上限制了这些方法在现场即时检测中的应用。便携式传感器允许用户利用小型化设备实时监测真菌毒素的污染情况，具有操作简便、用户友好、检测速度快、灵敏度高等优点，受到越来越多的科研工作者及社会各界人士的青睐。本文重点对试纸条、个人血糖仪、手持式pH计、气压计、智能手机、微流控芯片以及基于可视化、电化学、等离子体等输出信号的便携式生物传感器在真菌毒素检测中的应用和发展前景进行综述，以期为真菌毒素新型便携式生物传感器的研发提供参考。     

Risk Assessment of Mycotoxins and Predictive Mycology in Sri Lankan Spices: Chilli and Pepper

This research contributes to a better understanding of the mycotoxin problem associated with two important spices in world trade;, chilli and pepper by a multidisciplinary approach including analytical chemistry, risk assessment, food chemistry and predictive mycology. More specifically, this work provides important insights in mycotoxin contamination of these spices and associated risks in Sri Lanka. Firstly, a simple extraction method based on the QuEChERS approach was developed and successfully validated for the simultaneous determination of multiple mycotoxins using an advanced chromatographic technique, LC-MS/MS. The method was applied on complex spices for quantitative screening of seventeen mycotoxins. In addition to the classical aflatoxins and ochratoxin A, the spices were also found to be contaminated with several other toxicologically significant mycotoxins. Chilli samples (87%) were more frequently contaminated with mycotoxins than peppers (65%). Subsequently, the mycotoxins screening results and the collected consumption data were integrated in a quantitative risk assessment study. The results showed that AFB1 exposure via chilli consumption is of a public health concern in Sri Lanka, pepper is of lesser extent a risk due to the lower consumption. The toxigenic mould characterization in black peppers showed that Aspergillus flavus and/or Aspergillus parasiticus were the predominant moulds (73%) found, with considerable contamination (60%) of Penicillium spp. and A. niger. Furthermore, predictive mould growth models on peppercorns were developed at three temperatures and seven water activity levels for both A. flavus and A. parasiticus isolates. Based on the research, suitable storage conditions for black peppercorns were suggested and the way forward in managing the risk towards mycotoxins posed by the consumption of these two spices in Sri Lanka.     

Irradiation for Mold and Mycotoxin Control: A Review

The mycotoxin issue requires constant vigilance from economic, regulatory, and scientific agents to minimize its toxicological effects on human and animals. The implementation of good practices to avoid fungal growth and mycotoxin production on agricultural commodities is essential to achieve most restrictive safety standards; however, the contribution of novel technologies that may act on postharvesting and poststorage situations may be equally important. Several methodologies, more or less technologically advanced, may be used for this purpose. In this work, we review the role, contribution, and impact of irradiation technology to control the presence of fungi and mycotoxins in food and in feed. The effect of this technology on the viability of mold spores and on the elimination of mycotoxins is reviewed. A critical evaluation of the advantages and disadvantages of irradiation in this context is presented.     

粮食类饲料资源真菌毒素防制技术探讨

真菌毒素是一类有毒次级代谢物,对人畜健康有严重的影响,粮食饲料中一旦发生真菌毒素的污染,将对畜牧产品造成极大的经济损失.本文介绍了粮食饲料中真菌毒素的危害,并给出了可能的预防和控制措施.在真菌毒素控制方法中,根据它们降解毒素的不同原理,分成物理、化学、生物方法分别做了介绍.这些预防措施已经在一些领域使用.