**2. Occurrence of Aflatoxin in Oilseeds**

trile. *A. flavus* typically produces AFB1 and AFB2, whereas *A. parasiticus* produce AFG1 and AFG2 as well as AFB1 and AFB2. Four other aflatoxins M1, M2, B2A, G2A which may be produced in minor amounts were subsequently isolated from cultures of *A. flavus* and *A. parasiticus*. A number of closely related compounds namely aflatoxin GM1, parasiticol and aflatoxicol are also produced by *A. flavus.* The order of acute and chronic toxicity is AFB1 > AFG1 > AFB2 > AFG2, reflecting the role played by epoxidation of the 8,9-double bond and also the greater potency associated with the cyclopentenone ring of the B series, when com‐ pared with the six-membered lactone ring of the G series. AFM1 and AFM2 are hydroxylat‐ ed forms of AFB1 and AFB2 [5]. AFM1 and AFM2 are major metabolites of AFB1 and AFB2 in humans and animals and may be present in milk from animals fed on AFB1 and AFB2 contaminated feed [6, 7]. AFM1 may be also present in egg [8], corn [9] and peanut [10, 11].

AFs interact with the basic metabolic pathways of the cell disrupting key enzyme process‐ es including carbohydrate and lipid metabolism and protein synthesis [12]. The health ef‐ fects of aflatoxins have been reviewed by a number of expert groups. Aflatoxins are among the most potent carcinogenic, teratogenic and mutagenic compounds in nature [13]. The In‐ ternational Agency for Research on Cancer (IARC) has concluded that naturally occurring aflatoxins are carcinogenic to humans (group 1), with a role in etiology of liver cancer, no‐ tably among subjects who are carriers of hepatitis B virus surface antigens. In experimen‐ tal animals there was sufficient evidence for carcinogenicity of naturally occurring mixtures of aflatoxins and of AFB1, AFG1 and AFM1, limited evidence for AFB2 and inadequate evi‐ dence for AFG2. The principal tumors were in the liver, although tumors were also found at other sites including the kidney and colon. AFB1 is consistently genotoxic in vitro and

The Joint Food and Agriculture Organization of the United Nations (FAO)/World Health Organization (WHO) Expert Committee on Food Additives (JECFA) estimated potency val‐ ues for AFB1 from the epidemiological data. These corresponded to 0.3 cancers/year per 100,000 population per ng aflatoxin/kg body weight (b.w). per day (uncertainty range: 0.05-0.5) in hepatitis B virus antigen positive individuals and 0.01 cancers/year per 100,000 population per ng aflatoxin/kg b.w. per day (uncertainty range: 0.002-0.03) in hepatitis B vi‐ rus antigen negative individuals. AFM1 has been evaluated separately from AFB1 by the JECFA, because of its potential to be present in milk and milk products of livestock fed on aflatoxins contaminated feed [14]. The JECFA concluded that AFM1 should be presumed to induce liver cancer in rodents by a similar mechanism to AFB1, and that estimates of the po‐ tency of AFB1 can be used for determining the risk due to intake of AFM1, including those for populations with a high prevalence of carriers of hepatitis B virus. The carcinogenic po‐ tency of AFM1 was estimated to be one-tenth that of AFB1, based on a comparative study in

Humans can be exposed to aflatoxins by the periodic consumption of contaminated food, contributing to an increase in nutritional deficiencies, immunosuppression and hepatocellu‐ lar carcinoma. AFs have a wide occurrence in different kind of matrices, such as spices, cere‐ als, oils, fruits, vegetables, milk, meat, etc. [5]. About 4.5 billion people, mostly in developing countries, are at risk of chronic exposure to aflatoxins from contaminated food

in vivo [3].

144 Aflatoxins - Recent Advances and Future Prospects

the Fischer rat conducted by Cullen et al. [15].

Oilseed crops are primarily soybeans, sunflower seed, canola, rapeseed, safflower, flaxseed, mustard seed, peanuts and cottonseed, used for the production of cooking oils, protein meals for livestock, and industrial uses. These specific oilseeds are eligible for nonrecourse loans. Other oilseed crops include castor beans and sesame. After extraction of the oil the residue is a valuable source of protein, especially for animal feeding stuffs, as in oil-seed cake or press cake. Oilseeds and their products are mainly consumed as snacks as well as part of the ingredients of certain dishes in human daily diet [18].

According to many reports (Table 1), peanuts are the main susceptible products for aflatoxin contamination [19-21]. Tree nuts such as almonds, walnuts, and pistachios may be contami‐ nated with aflatoxin, though at lower levels than for cottonseed and corn; however, the problem is very significant to producers because: (1) the crop has a high unit value, and (2) much of the crop is sold to European markets that enforce limits significantly lower than those in some countries [22].

For over all sanitary precaution, the European Union has enacted in 1998, very severe afla‐ toxin tolerance standards of 2 µg kg-1 AFB1 and 4 µg kg-1 total aflatoxins for nuts and cere‐ als for human consumption and this has come into effect from January, 2001. Consumers in the developed world are well aware of the carcinogenic effect of aflatoxins and will thus stay away from a product that has aflatoxin beyond the acceptance level. Exports of agricul‐ tural products particularly groundnuts and other oilseeds from developing countries have dropped considerately in recent years resulting in major economic losses to producing coun‐ tries as a result of this restriction. According to the World Bank estimate, the policy change by the European Union will reduce by 64%, imports of cereals, dried fruits, oil seeds and nuts from nine African countries namely Chad, Egypt, Gambia, Mali, Nigeria, Senegal, South Africa, Sudan and Zimbabwe and this will cost African countries about US \$670 million in trade per year. However, the new rule of the EU has been criticized as being too strin‐ gent. There is the need for mycotoxin surveillance because of its wide occurrence in conta‐ minated commodities [23].

Aflatoxin contamination of peanut, resulting from invasion by *A. flavus* or *A. parasiticus*, is a major problem in semi-arid tropical regions where plants are primarily rain-fed. Light sandy soils, where peanut is typically cultivated, favor these fungi. While *A. flavus* infection of pea‐ nuts does not affect yield, the fungus can produce high levels of aflatoxin in infected nuts, and these toxins can pose serious health risks to humans and animals [24]. The environmen‐ tal conditions required to induce pre-harvest aflatoxin contamination of peanuts were stud‐ ied. In the study, peanuts did not become contaminated with aflatoxins in the absence of severe and prolonged drought stress even when the frequency of infection by *A. flavus* and *A. parasiticus* was up to 80%. Also, larger, more mature peanut kernels required considera‐ bly more drought stress to become contaminated than did smaller, immature kernels [25]. Peanuts become infected with aflatoxigenic fungus when seed pods come into direct contact with aflatoxigenic fungus in soil. These fungi can invade and produce toxins in peanut ker‐ nels before harvest, during drying, and in storage [26].

Peanut butter

Peanut butters

Cacao hazelnut cream

Diced almonds

Sesame paste

Unsorted, inshell almonds

California, USA

California, USA

a. Total: AFB1+ AFB2+ AFG1+ AFG2

c. ND: Not detected d. LOD: Limit of detection

**Table 1.** Aflatoxins in oilseeds.

Sudan 120/120 AFB1 17-170 Fluorome

China 31/33 Totale 0.7-96 UHPLC-

Turkey 38/40 Totala <0.625-10 ELISA [36]

10/74 Totala 1-107 TLC [37]

13/27 Totala <LOD-119 TLC [37]

Pistachio Turkey 48/95 Totala 0.007-7.72 HPLC [33]

Pistachio Iran 3699/10068 AFB1 5.9 ± 41.7 (Mean) HPLC [34] Hazelnut Egypt 18/20 Totala 25-175 TLC [35] Walnut Egypt 15/20 Totala 15-25 TLC [35] Walnut China 31/48 Totala 0.02-1.20 HPLC [28] Hazelnut Turkey 43/51 Totala <0.625-10 ELISA [36]

Sesame Malaysia 7/8 AFB1 0.54-1.82 ELISA [27]

Sunflower Malaysia 6/7 AFB1 1.14-5.33 ELISA [27] Nuts Malaysia 2/7 AFB1 0.66-1.09 ELISA [27] Pine nut China 2/12 Totala 0.19-0.25 HPLC [28]

Dried apricotIran 9/30 AFB1 "/0.2 HPLC [38] Prune Iran 2/15 AFB1 "/0.2 HPLC [38]

b. Total AFs including AFM1 (ND-64.7 ppb) and AFM2 (ND-3.6 ppb)

e. Total AFs including AFM1 (ND-4.2 ppb) and AFM2 (ND-1.8)

China 37/100 AFB1 <LOD-20.45 HPLC [31]

ter

MS/MS

[32]

Occurrence of Aflatoxins in Food http://dx.doi.org/10.5772/51031 147

[10]

Dried fruits can be contaminated with aflatoxins. Maximum permitted levels for total afla‐ toxins in the European Union are 4 µg kg−1 in dried fruit intended for direct human con‐ sumption. AFB1 was the most common mycotoxin encountered as a natural contaminant in stored samples [25].



a. Total: AFB1+ AFB2+ AFG1+ AFG2

b. Total AFs including AFM1 (ND-64.7 ppb) and AFM2 (ND-3.6 ppb)

c. ND: Not detected

d. LOD: Limit of detection

e. Total AFs including AFM1 (ND-4.2 ppb) and AFM2 (ND-1.8)

**Table 1.** Aflatoxins in oilseeds.

Aflatoxin contamination of peanut, resulting from invasion by *A. flavus* or *A. parasiticus*, is a major problem in semi-arid tropical regions where plants are primarily rain-fed. Light sandy soils, where peanut is typically cultivated, favor these fungi. While *A. flavus* infection of pea‐ nuts does not affect yield, the fungus can produce high levels of aflatoxin in infected nuts, and these toxins can pose serious health risks to humans and animals [24]. The environmen‐ tal conditions required to induce pre-harvest aflatoxin contamination of peanuts were stud‐ ied. In the study, peanuts did not become contaminated with aflatoxins in the absence of severe and prolonged drought stress even when the frequency of infection by *A. flavus* and *A. parasiticus* was up to 80%. Also, larger, more mature peanut kernels required considera‐ bly more drought stress to become contaminated than did smaller, immature kernels [25]. Peanuts become infected with aflatoxigenic fungus when seed pods come into direct contact with aflatoxigenic fungus in soil. These fungi can invade and produce toxins in peanut ker‐

Dried fruits can be contaminated with aflatoxins. Maximum permitted levels for total afla‐ toxins in the European Union are 4 µg kg−1 in dried fruit intended for direct human con‐ sumption. AFB1 was the most common mycotoxin encountered as a natural contaminant in

AFG1

Peanut Botswana 94/120 Totala 12-329 ELISA [20]

Peanut China 2/16 AFB1+AFB2 1.96 (mean) UHPLC [21] Peanut Malaysia 11/13 AFB1 1.47-15.33 ELISA [27] Peanut China 15/65 Totala 0.03-28.39 HPLC [28]

China 14/35 Totala 0.3-7.4 UHPLC-

China 5/5 Totalb 1.2-1482 UHPLC-

Trinidad 0/186 AFB1 NDc Charm II [29]

Brazil 41/80 Totala 43-1099 TLC [30]

China 41/50 AFB1 <LODd-68.51 HPLC [31]

**Aflatoxin Concentration (ppb)**

> 435-625 for AFB1 83-625 for AFG1

**Method Reference**

TLC [19]

MS/MS

MS/MS

[10]

[10]

nels before harvest, during drying, and in storage [26].

146 Aflatoxins - Recent Advances and Future Prospects

**Country Contaminated/**

Peanut Argentina 2/50 AFB1

**Total examined**

stored samples [25].

**Food Type**

Fresh Peanuts

Musty Peanuts

Peanut and products

Peanut and products

Peanut butter
