216
spp. In cool temperate zones, contamination of cereals with OTA occurs as the
result of invasion by P. verrucosum. Aspergillus westerdijkiae and other related species belonging to section Circumdati are found sporadically in a wide range of
stored commodities, including cereals, but are seldom the cause of substantial concentrations of OTA. However, since the first description of OTA production by
Aspergillus niger and Aspergillus carbonarius, members of Aspergillus section
Nigri have achieved greater significance because of their potential to contaminate
diverse food commodities with OTA (Alborch et al. 2011).
Environmental conditions such as moisture, temperature, incubation time, and
substrate type as well as other factors such as the presence of competitive flora and
the integrity of the seed (Marquardt and Frohlich 1992) play an important role in the
colonization by A. ochraceus and amount of ochratoxin produced. The most important factors influencing fungal development in stored grain ecosystems are the water
availability (water activity, a w ), storage temperature, and the intergranular gas composition (Ramos et al. 1998; Pardo et al. 2005).
A significant but often unrecognized toxin burden comes from coffee (StuderRohr et al. 1995), beer, and juices. Instant coffee is even more critical since it was
shown to contain significantly higher levels of OTA than coffee prepared from
roasted beans. Black tea was found not to be contaminated by OTA, whereas 42%
of children’s herbal teas contained relatively high toxin concentrations of up to
10 mg/kg.
OTA in meat and meat products presents a special problem (Gareis and Scheuer
2000), as OTA carryover from feed to meat has been shown experimentally (Madsen
et al. 1982). The kidney is highly contaminated followed by the liver, muscle, and
fat. Considerable amounts of OTA have also been found in blood (Mortensen et al.
1983), the incidence of OTA in blood sausages from swine being 77.2%, followed
by liver-type sausage (67.9%), and raw sausages (46.7%). This corresponds to maximum OTA levels of 4.6 and 3.2 ppb in blood- and liver-type sausages, respectively.
It was noted that OTA contamination of meat products, e.g., beef sausages, may also
arise from spices carrying the mycotoxin. In lean pork, only small amounts of the
mycotoxin, at a maximum concentration of 0.14 mg/kg, were detected, in as many
as 17.2% of the samples. OTA was essentially absent in meat from poultry, whereas
low-level OTA was present at levels around the detection limit of 0.01 mg/kg in
poultry sausage.
It was already noted that the repeated uptake of food with OTA concentrations
very close to or just above the recommended limit of 5 mg OTA/kg cereal or cereal
products means that the acceptable daily intake (ADI) of 5 ng OTA/kg BW per day
may be rapidly achieved (Petzinger and Ziegler 2000). Elimination of OTA in
humans is extremely slow, since the toxin has the longest half-life known for living
mammals. Repeated, almost daily uptake of OTA, therefore, will cause low albeit
toxicologically relevant toxin concentrations in blood. The delayed excretion of the
toxin in man may be due to reabsorption during an enterohepatic circulation, due to
reabsorption from the urine after tubular secretion, and due to extensive protein
binding. Since the toxin is ingested with almost every meal, humans may not be free
of toxin for very long periods. The toxin has been considered by the International
N. M. Abdelmotilib et al.
spp. In cool temperate zones, contamination of cereals with OTA occurs as the
result of invasion by P. verrucosum. Aspergillus westerdijkiae and other related species belonging to section Circumdati are found sporadically in a wide range of
stored commodities, including cereals, but are seldom the cause of substantial concentrations of OTA. However, since the first description of OTA production by
Aspergillus niger and Aspergillus carbonarius, members of Aspergillus section
Nigri have achieved greater significance because of their potential to contaminate
diverse food commodities with OTA (Alborch et al. 2011).
Environmental conditions such as moisture, temperature, incubation time, and
substrate type as well as other factors such as the presence of competitive flora and
the integrity of the seed (Marquardt and Frohlich 1992) play an important role in the
colonization by A. ochraceus and amount of ochratoxin produced. The most important factors influencing fungal development in stored grain ecosystems are the water
availability (water activity, a w ), storage temperature, and the intergranular gas composition (Ramos et al. 1998; Pardo et al. 2005).
A significant but often unrecognized toxin burden comes from coffee (StuderRohr et al. 1995), beer, and juices. Instant coffee is even more critical since it was
shown to contain significantly higher levels of OTA than coffee prepared from
roasted beans. Black tea was found not to be contaminated by OTA, whereas 42%
of children’s herbal teas contained relatively high toxin concentrations of up to
10 mg/kg.
OTA in meat and meat products presents a special problem (Gareis and Scheuer
2000), as OTA carryover from feed to meat has been shown experimentally (Madsen
et al. 1982). The kidney is highly contaminated followed by the liver, muscle, and
fat. Considerable amounts of OTA have also been found in blood (Mortensen et al.
1983), the incidence of OTA in blood sausages from swine being 77.2%, followed
by liver-type sausage (67.9%), and raw sausages (46.7%). This corresponds to maximum OTA levels of 4.6 and 3.2 ppb in blood- and liver-type sausages, respectively.
It was noted that OTA contamination of meat products, e.g., beef sausages, may also
arise from spices carrying the mycotoxin. In lean pork, only small amounts of the
mycotoxin, at a maximum concentration of 0.14 mg/kg, were detected, in as many
as 17.2% of the samples. OTA was essentially absent in meat from poultry, whereas
low-level OTA was present at levels around the detection limit of 0.01 mg/kg in
poultry sausage.
It was already noted that the repeated uptake of food with OTA concentrations
very close to or just above the recommended limit of 5 mg OTA/kg cereal or cereal
products means that the acceptable daily intake (ADI) of 5 ng OTA/kg BW per day
may be rapidly achieved (Petzinger and Ziegler 2000). Elimination of OTA in
humans is extremely slow, since the toxin has the longest half-life known for living
mammals. Repeated, almost daily uptake of OTA, therefore, will cause low albeit
toxicologically relevant toxin concentrations in blood. The delayed excretion of the
toxin in man may be due to reabsorption during an enterohepatic circulation, due to
reabsorption from the urine after tubular secretion, and due to extensive protein
binding. Since the toxin is ingested with almost every meal, humans may not be free
of toxin for very long periods. The toxin has been considered by the International
N. M. Abdelmotilib et al.