【黄曲霉素】

 

1960s: from elements of the modern Latin taxonomic name Aspergillus flavus + toxin.

The term "aflatoxin" is derived from the name of one of the molds that produce it, 

Aspergillus flavus. It was coined around 1960 after its discovery as the source of "Turkey X disease". 

Aflatoxins form one of the major groupings of mycotoxins.

 

Toxins	Producing fungi	Toxicities
Aflatoxin	Aspergillus flavus	Hepatocarcinogen
	Aspergillus parasiticus	and fatty liver

 

Aflatoxins are a family of toxins produced by certain fungi that are found on agricultural crops such as maize (corn), peanuts, cottonseed, and tree nuts. The main fungi that produce aflatoxins are Aspergillus flavus and Aspergillus parasiticus, which are abundant in warm and humid regions of the world. Aflatoxin-producing fungi can contaminate crops in the field, at harvest, and during storage.

 

 

Aflatoxins are quite stable compounds and survive relatively high temperatures with little degradation. Their heat stability is influenced by other factors, such as moisture level and pH, but heating or cooking processes cannot be relied upon to destroy aflatoxins. For example, roasting green coffee at 180^oC for 10 minutes gave only a 50% reduction in aflatoxin B₁ level.

The stability of aflatoxin M₁ in milk fermentation processes has also been studied and although appreciable losses do occur, significant quantities of the toxin were found to remain in both cheese and yoghurt.

Most mycotoxins are chemically and thermally stable though. While conventional food preparation with temperatures up to 100 °C have little effect on most mycotoxins, higher temperatures used in frying, roasting, toasting, and extrusion might reduce mycotoxin contamination.

Aflatoxins can be reduced by extrusion by 50–80 %, depending on grain moisture and temperature (Bullerman and Bianchini 2007). Alkaline treatment (see next chapter) can increase the efficacy of this process. Similar results were achieved for peanut meal, when extrusion alone reduced aflatoxins by 23–66 % and up to 87 % in the presence of ammonium hydroxide (Cheftel 1989). Roasting can reduce the levels of aflatoxins by 50–70 % in peanuts and pecans and by 40–80 % in maize (Conway et al. 1978). Pure aflatoxin B1(AFB1) was destroyed by temperatures above 160 °C; soybean matrix accelerated the process (Raters and Matissek 2008).

Roasting can reduce the content of OTA in coffee beans by up to 97 %, depending on the temperature and particle size (Oliveira et al.2013).

Degradation of OTA in wheat by heating (Boudra et al. 1995) and extrusion (Scudamore et al. 2004) was less efficient. Thermal degradation products of OTA are 14-(R)-ochratoxin A, 14-decarboxy-ochratoxin A and ochratoxin alpha amide, all of which have reduced toxicity (Cramer et al. 2008; Bittner et al. 2015). Cazzaniga et al. (2001) reported drastic reduction of the level of DON under all investigated conditions but other labs found moderate effects depending on the conditions (Wu et al. 2011) or no reduction of DON and nivalenol (NIV) (Scudamore et al. 2008). Extrusion cooking of maize grits contaminated with ZEN reduced the toxin content by 65–83 % (Ryu et al. 1999). Extrusion or roasting was also effective in reducing fumonisins in maize grits by 34–95 % (Bullerman and Bianchini 2007). Increased temperature, decreased screw speed, and glucose addition resulted in higher reduction rates during extrusion. Thermal treatment always involves transformation reactions. Fumonisin in corn extruded with glucose (Bullerman and Bianchini 2007) yielded N-(1-deoxy-d-fructos-1-yl)-fumonisin B1, a compound less toxic than fumonisin B1 to rats (Hahn et al. 2015). Citrinin (CIT) could also be efficiently degraded by heating (Trivede et al. 1992). EAs are partly degraded and epimerized during bread baking; the ratio between epimers shifts towards the -inine forms (EFSA 2012; Merkel et al. 2012).

Around 100 countries around the world have regulations governing aflatoxins in food and most include maximum permitted, or recommended levels for specific commodities.

EU

The EU sets limits for aflatoxin B₁ and for total aflatoxins (B₁, B₂, G₁ and G₂) in nuts, dried fruits, cereals and spices. Limits vary according to the commodity, but range from 2-12 μg/kg for B₁ and from 4-15 μg/kg for total aflatoxins. There is also a limit of 0.050 μg/kg for aflatoxin M₁ in milk and milk products. Sampling and analytical methods are also specified.

Limits of 0.10 μg/kg for B₁ and 0.025 μg/kg for M₁ have been set for infant foods.

USA

US food safety regulations include a limit of 20 μg/kg for total aflatoxins (B₁, B₂, G₁ and G₂) in all foods except milk and a limit of 0.5 μg/kg for M₁ in milk. Higher limits apply in animal feeds.

Others

Both Australia and Canada set limits of 15 μg/kg for total aflatoxins (B₁, B₂, G₁ and G₂) in nuts. This is the same as the international limit recommended for raw peanuts by the Codex Alimentarius Commission.

Toxins	Producing fungi	Toxicities
Aflatoxin	Aspergillus flavus	Hepatocarcinogen
	Aspergillus parasiticus	and fatty liver