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Occurrence and Importance of Mycotoxins in FoodsDuring different food processing technologies, including cooking, boiling, baking, frying, baking,and pasteurizing, most mycotoxins remain chemically and thermally stable.
Food processing can lead to a reduction of contaminants, such as mycotoxins. However, for food processing operations where thermal energy is employed, it is often not clear whether a reduction of mycotoxins also results in a mitigation of the toxicological impact. This is often due to the reason that the formed degradation products are not characterized and data on their toxicity is scarce.
in food processing operations where thermal energy is used (e.g. baking [5], nixtamalization [3], extrusion [6] and roasting [7]), mycotoxins may be degraded by reactions with chemicals, enzymes or matrix components. The degradation products may have different toxicokinetic and toxicodynamic properties than the parent mycotoxin.
Thermal food processing was shown to be effective in reducing the concentration of trichothecenes (e.g. deoxynivalenol (DON)), ochratoxin A (OTA), zearalenone (ZEN), aflatoxins (e.g. aflatoxin B1 (AfB1)) and fumonisins (e.g. fumonisin B1 (FB1)) [1]. Although many studies on the reduction of mycotoxins during food processing exist, much less information about the formed degradation products is available.
Toxicity studies show that the degradation products can have a completely different toxicity than the parent mycotoxins. For example, isoDON [5], norDONs A–C [11], norNIVs A–C [12] and NCM-FB1 [13] were found to be considerably less toxic than the respective parent mycotoxin. Some degradation products, such as 14-R-OTA which was shown to be a factor 10 less cytotoxic than OTA, can retain some toxicity [14]. Therefore, the identification and quantification of not only the parent mycotoxin but also the formed degradation products are essential for a complete risk assessment of the toxicological impact of mycotoxins that are present in thermally processed food commodities.
AflatoxinsAflatoxins are secondary metabolites, and they belong to the category of difuranocoumarins [44].Under warm and humid conditions,Aspergillus flavus, A. nomius, andA. parasiticusproduce AFs [22,45],commonly found in food and feeds. The speciesA. flavusandA. parasiticusare found worldwide in thesoil and in the air [46], preferring to grow at temperatures between 22 and 35◦C and awbetween 0.95and 0.98 [47]. Other species producing aflatoxins similar toA. flavusareA. zhaoqingensisandA. bombycis,while those similar toA. parasiticusareA. toxicariusandA. parvisclerotigenus. Moreover,A. pseudotamarii,A. ochraceoroseus,A. rambellii,A. toxicarius,Emericella astellata,E. olivicola, andE. venezuelensisaresome species of mycotoxin producers. Two other recently described aflatoxigenic species areA.minisclerotigenesandA. arachidicola[48].AFs are the best known among all mycotoxins, because of their serious impact on human andanimal health. Four main types of aflatoxins are the most studied among more than 20 known ones;these are aflatoxin AFB1, AFB2, AFG1, and AFG2, named after the fluorescence they display in UVlight (B for blue and G for green). The hydroxylated metabolites of AFB1 and AFB2 are aflatoxinM1 (AFM1) and aflatoxin M2 (AFM2), which are present in the meat of animals that consumedaflatoxin-contaminated feed, as well as animal products such as eggs, milk, and cheese [22]. AflatoxinB1 is a carcinogenic substance (according to the classification by the IARC in 1987) (category 1A), whileAFM1 is a potentially carcinogenic substance (category 2B) [49], with a toxicity range of B1>G1>B2>G2 [50]. AFB1 is considered to be the most potent carcinogenic toxin known in mammals [51], and foodcontamination should be reduced to the lowest possible level, since no food or health organizationestablished a tolerable daily intake for humans (tolerable daily intake, TDI) [52]. Exposure to chronichepatitis B virus infection and aflatoxin may increase liver cancer risk by up to 30 times compared tothe risk in individuals exposed to aflatoxin only [53]. The risk of exposure to contaminated foods withvarying levels of AFs worldwide exists for more than 4.5 billion people [54]. At present, levels of AFsin food and feed are established in approximately 100 countries [55]. The EU legal limit for AFB1 inprocessed cereal foods is 0.02μg/kg [56]. Different maximum upper limits are set worldwide for AFM1in milk or milk products, with Codex Alimentarius and the EU setting the limit to 0.05μg/kg AFM1,whereas the US and some Latin American countries set it to 0.
Because the production of AFs depends on the awinteraction with temperature, maintaining thetemperature in the storage area below 15◦C leads to minimum awfor the production of mycotoxins at0.934. Moreover, the formation of AFs can cause damage to the products [59].Aflatoxins are linked to various diseases, such as aflatoxicosis, in animals, pets, and humans aroundthe world [44], and they are considered to be particularly harmful as they have carcinogenic, mutagenic(DNA damaging), teratogenic, and immunosuppressive effects [51]. Symptoms of acute aflatoxicosisin humans include vomiting, abdominal pain, jaundice, pulmonary edema, coma, convulsions, anddeath [5,60], while chronic aflatoxicosis occurs via cancer, immune system inhibition, and liver damage.There are significant differences in species sensitivity, with the size of the reaction depending on avariety of factors, such as age, sex, weight, nutrition, metabolism, exposure to infectious agents, andthe occurrence of other mycotoxins [5], as well as the type of toxin, mechanism of action, and levels ofintake.
Processing techniques can reduce the concentration of mycotoxins, but they cannot completelydestroy them [257]. The level of mycotoxin contamination can be reduced by softening, because thefungi accumulate on the surface of the granules. A study in Kenya showed a decrease in AFs in maizeby peeling. The final flour was less contaminated, while mycotoxins DON and ZEN were detected onthe surface of the granules at high levels. Temperature and time can affect the mycotoxin content of thefinal product. Although mycotoxins are thermally stable compounds, some conventional methodsof preparing food (baking, frying) at temperatures above 100◦C may reduce certain mycotoxins.The processing temperature and moisture content of the granules affect the reduction of AFs by50%–80% during the extrusion process [258]. Moreover, temperatures of 150–200◦C significantlyreduced AFB1, causing 79% average reduction, being more effective at high humidity [259
Occurrence and Importance of Mycotoxins in FoodsDuring different food processing technologies, including cooking, boiling, baking, frying, baking,and pasteurizing, most mycotoxins remain chemically and thermally stable.
Food processing can lead to a reduction of contaminants, such as mycotoxins. However, for food processing operations where thermal energy is employed, it is often not clear whether a reduction of mycotoxins also results in a mitigation of the toxicological impact. This is often due to the reason that the formed degradation products are not characterized and data on their toxicity is scarce.
in food processing operations where thermal energy is used (e.g. baking [5], nixtamalization [3], extrusion [6] and roasting [7]), mycotoxins may be degraded by reactions with chemicals, enzymes or matrix components. The degradation products may have different toxicokinetic and toxicodynamic properties than the parent mycotoxin.
Thermal food processing was shown to be effective in reducing the concentration of trichothecenes (e.g. deoxynivalenol (DON)), ochratoxin A (OTA), zearalenone (ZEN), aflatoxins (e.g. aflatoxin B1 (AfB1)) and fumonisins (e.g. fumonisin B1 (FB1)) [1]. Although many studies on the reduction of mycotoxins during food processing exist, much less information about the formed degradation products is available.
Toxicity studies show that the degradation products can have a completely different toxicity than the parent mycotoxins. For example, isoDON [5], norDONs A–C [11], norNIVs A–C [12] and NCM-FB1 [13] were found to be considerably less toxic than the respective parent mycotoxin. Some degradation products, such as 14-R-OTA which was shown to be a factor 10 less cytotoxic than OTA, can retain some toxicity [14]. Therefore, the identification and quantification of not only the parent mycotoxin but also the formed degradation products are essential for a complete risk assessment of the toxicological impact of mycotoxins that are present in thermally processed food commodities.
AflatoxinsAflatoxins are secondary metabolites, and they belong to the category of difuranocoumarins [44].Under warm and humid conditions,Aspergillus flavus, A. nomius, andA. parasiticusproduce AFs [22,45],commonly found in food and feeds. The speciesA. flavusandA. parasiticusare found worldwide in thesoil and in the air [46], preferring to grow at temperatures between 22 and 35◦C and awbetween 0.95and 0.98 [47]. Other species producing aflatoxins similar toA. flavusareA. zhaoqingensisandA. bombycis,while those similar toA. parasiticusareA. toxicariusandA. parvisclerotigenus. Moreover,A. pseudotamarii,A. ochraceoroseus,A. rambellii,A. toxicarius,Emericella astellata,E. olivicola, andE. venezuelensisaresome species of mycotoxin producers. Two other recently described aflatoxigenic species areA.minisclerotigenesandA. arachidicola[48].AFs are the best known among all mycotoxins, because of their serious impact on human andanimal health. Four main types of aflatoxins are the most studied among more than 20 known ones;these are aflatoxin AFB1, AFB2, AFG1, and AFG2, named after the fluorescence they display in UVlight (B for blue and G for green). The hydroxylated metabolites of AFB1 and AFB2 are aflatoxinM1 (AFM1) and aflatoxin M2 (AFM2), which are present in the meat of animals that consumedaflatoxin-contaminated feed, as well as animal products such as eggs, milk, and cheese [22]. AflatoxinB1 is a carcinogenic substance (according to the classification by the IARC in 1987) (category 1A), whileAFM1 is a potentially carcinogenic substance (category 2B) [49], with a toxicity range of B1>G1>B2>G2 [50]. AFB1 is considered to be the most potent carcinogenic toxin known in mammals [51], and foodcontamination should be reduced to the lowest possible level, since no food or health organizationestablished a tolerable daily intake for humans (tolerable daily intake, TDI) [52]. Exposure to chronichepatitis B virus infection and aflatoxin may increase liver cancer risk by up to 30 times compared tothe risk in individuals exposed to aflatoxin only [53]. The risk of exposure to contaminated foods withvarying levels of AFs worldwide exists for more than 4.5 billion people [54]. At present, levels of AFsin food and feed are established in approximately 100 countries [55]. The EU legal limit for AFB1 inprocessed cereal foods is 0.02μg/kg [56]. Different maximum upper limits are set worldwide for AFM1in milk or milk products, with Codex Alimentarius and the EU setting the limit to 0.05μg/kg AFM1,whereas the US and some Latin American countries set it to 0.
Because the production of AFs depends on the awinteraction with temperature, maintaining thetemperature in the storage area below 15◦C leads to minimum awfor the production of mycotoxins at0.934. Moreover, the formation of AFs can cause damage to the products [59].Aflatoxins are linked to various diseases, such as aflatoxicosis, in animals, pets, and humans aroundthe world [44], and they are considered to be particularly harmful as they have carcinogenic, mutagenic(DNA damaging), teratogenic, and immunosuppressive effects [51]. Symptoms of acute aflatoxicosisin humans include vomiting, abdominal pain, jaundice, pulmonary edema, coma, convulsions, anddeath [5,60], while chronic aflatoxicosis occurs via cancer, immune system inhibition, and liver damage.There are significant differences in species sensitivity, with the size of the reaction depending on avariety of factors, such as age, sex, weight, nutrition, metabolism, exposure to infectious agents, andthe occurrence of other mycotoxins [5], as well as the type of toxin, mechanism of action, and levels ofintake.
Processing techniques can reduce the concentration of mycotoxins, but they cannot completelydestroy them [257]. The level of mycotoxin contamination can be reduced by softening, because thefungi accumulate on the surface of the granules. A study in Kenya showed a decrease in AFs in maizeby peeling. The final flour was less contaminated, while mycotoxins DON and ZEN were detected onthe surface of the granules at high levels. Temperature and time can affect the mycotoxin content of thefinal product. Although mycotoxins are thermally stable compounds, some conventional methodsof preparing food (baking, frying) at temperatures above 100◦C may reduce certain mycotoxins.The processing temperature and moisture content of the granules affect the reduction of AFs by50%–80% during the extrusion process [258]. Moreover, temperatures of 150–200◦C significantlyreduced AFB1, causing 79% average reduction, being more effective at high humidity [259