**1. Introduction**

Cereals and cereal by‐products constitute a major part of the daily human and animal diet. Latest estimates for world cereal production in 2015 and EU‐28 in 2014 are approximately 2540 and 323 mil tons, respectively [1]. According to the Food and Agriculture Organization of the United Nations (FAO), rice, maize, and wheat are staple foods for 4 bn people and make up about 60% of the world's food energy intake [2]. The FAO estimated that the global

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consumption for wheat is about 66 kg/per capita [3]. Among the most important risks associ‐ ated with cereal consumption are mycotoxins, heavy metals, pesticide residues, and alka‐ loids. Richard et al. [4] estimated annual losses of \$932 million in stored grain in the United States due to mycotoxin contamination. Cereal and cereal products can be contaminated with mycotoxins produced by a variety of fungi that colonize crops in the field or postharvest [5–8]. Mycotoxins are toxic secondary fungal metabolites that can cause a variety of adverse health effects in humans and animals, depending on the type of mycotoxin and the contamination levels. There are 300–400 mycotoxins known today. However, for practical consideration in food manufacturing, because of their worldwide occurrence and concern regarding human and animal diseases, the number is considerably less. The most important mycotoxins in wheat are mainly *Fusarium* toxins, such as deoxynivalenol (DON), zearalenone (ZEA), nivale‐ nol (NIV), fumonisins (FUM), T‐2, and HT‐2 toxins [8–14]. Moreover, recent studies provided increased evidence for the presence of modified *Fusarium* mycotoxins and so‐called emerging mycotoxins, particularly enniatins [15, 16]. Multi‐mycotoxin contamination is the most com‐ mon type of contamination [10, 14, 17–22]. This is a topic of great concern, as co‐contaminated samples might still exert adverse health effects due to additive/synergistic interactions of the mycotoxins.

Mycotoxin regulations have been established in more than 100 countries, and the maximum acceptable limits vary greatly from country to country. The globalization of the trade in agri‐ cultural commodities and the lack of legislative harmonization have contributed significantly to the discussion about the awareness of mycotoxins entering the food supply chain. The European Union harmonized regulations for the maximum levels of mycotoxins in food and feed [23, 24]. Moreover, two EFSA scientific opinions recommended that the presence of mod‐ ified and emerging mycotoxins must be considered by the European legislation in the near future [25, 26].

Fungal growth and mycotoxin contamination can occur during several steps of the food sup‐ ply chain. Despite efforts in controlling fungal growth, mycotoxin co‐contamination repre‐ sents an unavoidable risk, occurring pre‐ and postharvest and resulting in reduced nutritional value and possible risks for human and animal health. In addition to health risks, fungal growth and mycotoxins have a detrimental effect on the quality and the processing perfor‐ mance of wheat. *Fusarium* damage may reduce wheat milling performance and affect flour yield and flour ash, with a strong negative effect on flour brightness, and baking performance [27–29].

Many factors with pre‐ and postharvest origins must be taken into account to manage the challenge of mycotoxins in wheat. Preharvest events are predominantly dictated by environ‐ mental factors and good agronomic/cultural practices, whereas storage and processing are the major areas where contamination can be prevented at postharvest level. The aim of this chapter is to present an overview of the most recent findings on wheat mycotoxin contamina‐ tion and of the main pre‐ and postharvest strategies as mitigation measures, focusing on those more consolidated and used by the wheat industry chain. Other promising measures, but still studied at research level, will be presented with papers and reviews to which the reader is directed for specific insights.

**2. Mycotoxin occurrence in wheat**

consumption for wheat is about 66 kg/per capita [3]. Among the most important risks associ‐ ated with cereal consumption are mycotoxins, heavy metals, pesticide residues, and alka‐ loids. Richard et al. [4] estimated annual losses of \$932 million in stored grain in the United States due to mycotoxin contamination. Cereal and cereal products can be contaminated with mycotoxins produced by a variety of fungi that colonize crops in the field or postharvest [5–8]. Mycotoxins are toxic secondary fungal metabolites that can cause a variety of adverse health effects in humans and animals, depending on the type of mycotoxin and the contamination levels. There are 300–400 mycotoxins known today. However, for practical consideration in food manufacturing, because of their worldwide occurrence and concern regarding human and animal diseases, the number is considerably less. The most important mycotoxins in wheat are mainly *Fusarium* toxins, such as deoxynivalenol (DON), zearalenone (ZEA), nivale‐ nol (NIV), fumonisins (FUM), T‐2, and HT‐2 toxins [8–14]. Moreover, recent studies provided increased evidence for the presence of modified *Fusarium* mycotoxins and so‐called emerging mycotoxins, particularly enniatins [15, 16]. Multi‐mycotoxin contamination is the most com‐ mon type of contamination [10, 14, 17–22]. This is a topic of great concern, as co‐contaminated samples might still exert adverse health effects due to additive/synergistic interactions of the

Mycotoxin regulations have been established in more than 100 countries, and the maximum acceptable limits vary greatly from country to country. The globalization of the trade in agri‐ cultural commodities and the lack of legislative harmonization have contributed significantly to the discussion about the awareness of mycotoxins entering the food supply chain. The European Union harmonized regulations for the maximum levels of mycotoxins in food and feed [23, 24]. Moreover, two EFSA scientific opinions recommended that the presence of mod‐ ified and emerging mycotoxins must be considered by the European legislation in the near

Fungal growth and mycotoxin contamination can occur during several steps of the food sup‐ ply chain. Despite efforts in controlling fungal growth, mycotoxin co‐contamination repre‐ sents an unavoidable risk, occurring pre‐ and postharvest and resulting in reduced nutritional value and possible risks for human and animal health. In addition to health risks, fungal growth and mycotoxins have a detrimental effect on the quality and the processing perfor‐ mance of wheat. *Fusarium* damage may reduce wheat milling performance and affect flour yield and flour ash, with a strong negative effect on flour brightness, and baking performance

Many factors with pre‐ and postharvest origins must be taken into account to manage the challenge of mycotoxins in wheat. Preharvest events are predominantly dictated by environ‐ mental factors and good agronomic/cultural practices, whereas storage and processing are the major areas where contamination can be prevented at postharvest level. The aim of this chapter is to present an overview of the most recent findings on wheat mycotoxin contamina‐ tion and of the main pre‐ and postharvest strategies as mitigation measures, focusing on those more consolidated and used by the wheat industry chain. Other promising measures, but still studied at research level, will be presented with papers and reviews to which the reader is

mycotoxins.

228 Wheat Improvement, Management and Utilization

future [25, 26].

[27–29].

directed for specific insights.

**Figure 1.** World mycotoxin occurrence (% of positive samples) in wheat and wheat bran (modified from Ref. [8]).

Results from worldwide mycotoxin occurrence studies indicate that DON is the most common mycotoxin contaminant of wheat and wheat‐based products. Moreover, results highlighted the presence of considerable differences regarding the type and prevalence of mycotoxin contamination in different regions of the world, confirming that contamination is strongly dependent on regional climatic conditions [10, 14, 17–22]. Differences in mycotoxin occur‐ rence and concentration between distant geographical areas are uncontroversial. Within each geographical area, seasonal and local weather conditions during critical crop growing stages are of great importance to explain the variation in mycotoxin occurrence. In general, envi‐ ronmental conditions, such as excessive moisture, temperature extremes, humidity, drought conditions, insect damage, crop systems, and some agronomic practices, can cause stress and predispose wheat in the field to mold and determine the severity of mycotoxin contamination [20, 30–32]. Moreover, the high variability in the occurrence and level of mycotoxins may be the results of several factors, such as the years of the surveys, the annual weather fluctuations, and the storage conditions (**Figure 2**).

Data on the occurrence of *Fusarium* mycotoxins in durum wheat are quite limited. Available data indicated that durum wheat was generally more contaminated than common wheat, but, with the exception of a few samples, no durum wheat sample was noncompliant to the maximum permitted level for DON and ZEA [33].

Another important point highlighted from studies on the worldwide mycotoxin occurrence in wheat and cereals is that the levels of detected mycotoxins are extremely variable. Average

The major mycotoxins occurring in wheat, at levels of potential concern for human and ani‐ mal health, are *Fusarium* mycotoxins [8–14] (**Figure 1**).

levels of mycotoxin contamination may be low and rarely exceed risk threshold levels, but as the content range is very wide, several samples may exceed the maximum or recommended levels for mycotoxin contamination (**Table 1**) [11, 14, 17, 18, 20, 22, 34].

**Figure 2.** Year‐by‐year average mycotoxin concentration in wheat and wheat bran samples (modified from Ref. [20]).


AFLA, aflatoxins; DON, deoxynivalenol; FUM, fumonisins; OTA, ochratoxin A; T‐2, T‐2 toxin; ZEA, zearalenone; Aw, water activity; n.a., not available; W, wheat for direct human consumption; UW, unprocessed wheat.

\*Commission Regulation (EC) No 1881/2006 of 19 December 2006 setting maximum levels for certain contaminants in foodstuffs.

\*\*Indicates recommendations (2013/165/EU: Commission Recommendation of 27 March 2013 on the presence of T‐2 and HT‐2 toxin in cereals and cereal products).

**Table 1.** Results of mycotoxin occurrence in wheat in 2015 (modified from Ref. [22]).

Another important point highlighted from mycotoxin researches is that mycotoxin co‐con‐ tamination is more the rule than the exception. Several studies reported a high incidence of multi‐mycotoxin contamination in cereals and agricultural commodities [10, 14, 17–22]. A recent survey showed that in 2015, 46% of wheat samples were co‐contaminated by two to six mycotoxins [35]. A study carried out in Italy showed that at least 80% of wheat samples were contaminated with one mycotoxin, while two mycotoxins were found in 27% of contam‐ inated samples; 38% of the analyzed samples were contaminated with three or more myco‐ toxins [36]. Multi‐mycotoxin contamination is a topic of great concern, as co‐contaminated samples, although at lower levels than those indicated by EU regulations, might still exert adverse effects on animals due to additive/synergistic interactions of the mycotoxins.

A further scenario is represented by the climate changes. Estimates suggest that climate change will reduce wheat production globally by 29–34% by 2050 in developing countries [37]. This will have a great impact on food security. In terms of food safety and mycotoxin contamination, although aflatoxin is the mycotoxin that is most likely to increase under near‐ future climate scenario, problems concerning also *Fusarium* toxins may represent a challenge if the temperature increases in cool or temperate climate countries [38, 39].

In terms of mycotoxin contamination, new issues for cereal safety include both emerging mycotoxins and modified forms [15, 16, 25, 26, 40]. Mycotoxin contamination by emerging *Fusarium* mycotoxins, such as beauvericin and enniatins, represents a problem of global con‐ cern, especially in Northern Europe [15, 25, 36, 40]. Modified mycotoxins represent another emerging topic. Plant metabolites have been identified so far for DON, NIV, fusarenon‐X, T‐2 toxin, HT‐2 toxin, ZEA, ochratoxin A (OTA), destruxins, fusaric acid, and modified fumonisins have been found, especially in wheat and other cereal commodities [41–46]. The acetylated derivatives of DON, 3‐ADON, and 15‐ADON are frequently detected in DON‐contaminated grains [47].
