Foreword

The safety of food and feed—in particular the presence of food contaminants—has become of increasing concern for consumers, governments and producers. Trace levels of chemical contaminants can originate from natural sources such as mycotoxins, which are secondary metabolites produced by fungi on agricultural commodities in the field and during storage under a wide range of climatic conditions. The occurrence of mycotoxin contamination in various crops is of major concern since it has significant implications for food and feed safety, food security and international trade. The Food and Agriculture Organization (FAO) has estimated that 25% of the world's food crops are affected by mycotoxins, including many basic foodstuffs and animal feeds. In fact, due to the availability of ultra-sensitive high-performance analytical instrumentation, especially in modern liquid chromatography–mass spectrometry (LC-MS), the percentage of samples that have tested positive for mycotoxins in more recent studies is actually much higher. More than 300 mycotoxins have been identified so far with widely different chemical structures and differing modes of action—some target the kidney, liver or the immune system and some are carcinogenic. Common mycotoxins include trichothecenes, such as deoxynivalenol, fumonisins, zearalenone, ochratoxin A and aflatoxins. The potential health risks to animals and humans posed by food- and feed-borne mycotoxin intoxication have been recognised by national and international institutions and organisations such as the European Commission (EC) and its European Food Safety Authority (EFSA), the US Food and Drug Administration (FDA), the World Health Organisation (WHO) and the FAO, which has resulted in improved risk assessment and adopted regulatory limits for major mycotoxin classes and selected individual mycotoxins.

The term “masked mycotoxins”, introduced in 1990, has now been established internationally as mycotoxin derivatives that are undetectable by conventional analytical techniques because their structure has been changed in the plant. In the last decade, masked mycotoxins have become a hot topic in mycotoxin research. To harmonise future scientific wording and subsequent legislation, it has been suggested to use the term “masked mycotoxins” for the fraction of biologically modified mycotoxins that were conjugated by plants.

The role of plant metabolites of mycotoxins is manifold. First and foremost, plants are capable of overcoming or at least diminishing fungal invasion by a variety of mechanisms. The metabolisation of xenobiotics to less deleterious compounds, such as masked mycotoxins, obviously is an important one. Plant breeding efforts have been leading to the selection for those varieties that are more efficient at detoxifying pathogenicity or virulence factors, such as certain mycotoxins. It is therefore not too surprising that a multitude of masked mycotoxins must exist. The tremendous pace in the development of modern analytical equipment and methods has enabled the discovery of many such compounds, in particular during the last couple of years. While there are still plenty of shortcomings to overcome—including the lack of analytical standards, the trueness of analytical results or matrix reference materials—the (analytical) community has taken some important steps in the right direction.

Food safety has to address all compounds with potential negative health effects. Hence, masked mycotoxins along with their parent compounds have to be considered within a sound risk assessment analysis. If and to what extent masked mycotoxins are risk factors for humans and animals is a question that will keep scientists in the field of mycotoxins busy for years to come. The assumption that masked mycotoxins are cleaved during digestion took surprisingly long to prove, showing how complex the topic is. While certain gut microbes that are more abundant in certain animal species are quite capable of cleaving masked mycotoxins, others are not. Only recently has the direct action of masked mycotoxins before cleavage been assessed. Equally importantly, masked mycotoxins might liberate toxins in areas of the body in which mycotoxins normally do not occur.

This is the first book that is exclusively dedicated to the topic of masked mycotoxins and all its facets. It will provide the interested reader with an excellent overview on the topic as well as with detailed insights into the rapidly developing field of these important mycotoxin metabolites produced by plants. In particular, analytical methods, the occurrence of masked mycotoxins, the potential effects of food processing and in vitro and in vivo toxicity assessment, as well as detoxification strategies for mycotoxins in plant breeding, are discussed in dedicated chapters. Masked Mycotoxins in Food enables both the newcomer and the veteran in the field to get a full picture of the current knowledge on masked mycotoxins.

Enjoy reading this book!

Rudolf Krska

University of Natural Resources and Life Sciences, Vienna, Austria