Mycotoxins
711
Figure 30–1 Growth and aflatoxin B 1 production on malt extract-glycerine agar at various water activity values
and temperatures. White columns: rate of growth; black columns: average AFB 1 production. Source: From
Northolt et al.,
63 copyright c
1976 by International Association of Milk, Food and Environmental Sanitarians.
The limiting moisture content for AFB 1 and AFB 2 on corn was 17.5% at a temperature of 24
◦ C or
higher, with up to 50 ng/g being produced.
96 No toxin was produced at 13
◦ C. Overall, toxin production
has been observed over the a w range of 0.93–0.98, with limiting values variously reported as being
0.71–0.94.
58 In another study, no detectable quantities of AFB 1 were formed by A. parasiticus at
a w values of 0.83 at 10
◦ C.
63 The optimum temperature at a w 0.94 was 24
◦ C (Figure 30–1). Growth
without demonstrable toxin appeared possible at a w 0.83 on malt agar containing sucrose. It has
been observed by several investigators that rice supports the production of high levels of aflatoxins at
favorable temperatures but none is produced at 5
◦ C on either rice or cheddar cheese.
68
Overall, the minimal and maximal parameters that control growth and toxin production by these
eukaryotic organisms are not easy to define, in part because of their diverse habitats in nature and in
part because of their eukaryotic status. It seems clear that growth can occur without toxin production.
AFG 1 is produced at lower growth temperatures than AFB 1 , and while some investigators have
found more AFB 1 than AFG 1 at around 30
◦ C, others have found equal production. With regard to
A. flavus and A. parasiticus, the former generally produces only AFB 1 and AFG 1 .
22 Aeration favors
aflatoxin production, and amounts of 2 mg/g can be produced on natural substrates such as rice, corn,
soybeans, and the like.
22 Up to 200–300 mg/l can be produced in broth containing appropriate levels
of Zn
2+ . The release of AFB 1 by A. flavus appears to involve an energy-dependent transport system.
Production and Occurrence in Foods
With respect to production in foods, aflatoxin has been demonstrated on fresh beef, ham, and bacon
inoculated with toxigenic cultures and stored at 15
◦ , 20
◦ , and 30
◦ C,
9 and on country-cured hams
711
Figure 30–1 Growth and aflatoxin B 1 production on malt extract-glycerine agar at various water activity values
and temperatures. White columns: rate of growth; black columns: average AFB 1 production. Source: From
Northolt et al.,
63 copyright c
1976 by International Association of Milk, Food and Environmental Sanitarians.
The limiting moisture content for AFB 1 and AFB 2 on corn was 17.5% at a temperature of 24
◦ C or
higher, with up to 50 ng/g being produced.
96 No toxin was produced at 13
◦ C. Overall, toxin production
has been observed over the a w range of 0.93–0.98, with limiting values variously reported as being
0.71–0.94.
58 In another study, no detectable quantities of AFB 1 were formed by A. parasiticus at
a w values of 0.83 at 10
◦ C.
63 The optimum temperature at a w 0.94 was 24
◦ C (Figure 30–1). Growth
without demonstrable toxin appeared possible at a w 0.83 on malt agar containing sucrose. It has
been observed by several investigators that rice supports the production of high levels of aflatoxins at
favorable temperatures but none is produced at 5
◦ C on either rice or cheddar cheese.
68
Overall, the minimal and maximal parameters that control growth and toxin production by these
eukaryotic organisms are not easy to define, in part because of their diverse habitats in nature and in
part because of their eukaryotic status. It seems clear that growth can occur without toxin production.
AFG 1 is produced at lower growth temperatures than AFB 1 , and while some investigators have
found more AFB 1 than AFG 1 at around 30
◦ C, others have found equal production. With regard to
A. flavus and A. parasiticus, the former generally produces only AFB 1 and AFG 1 .
22 Aeration favors
aflatoxin production, and amounts of 2 mg/g can be produced on natural substrates such as rice, corn,
soybeans, and the like.
22 Up to 200–300 mg/l can be produced in broth containing appropriate levels
of Zn
2+ . The release of AFB 1 by A. flavus appears to involve an energy-dependent transport system.
Production and Occurrence in Foods
With respect to production in foods, aflatoxin has been demonstrated on fresh beef, ham, and bacon
inoculated with toxigenic cultures and stored at 15
◦ , 20
◦ , and 30
◦ C,
9 and on country-cured hams