acids evaluated. The pH of the adjusted sorghum (data
not presented) was essentially the same as those registered
for extrudates (Table 1). As the MC and acid concentration
increased, lower pH values were observed. Samples
with no acid (control) presented a pH value of 6Æ10,
while the lowest pH values of 3Æ47 and 3Æ74 were
observed in samples prepared with 30% MC and
8Æ0 mol l)1 lactic and citric acid respectively. EU adjusted
with lactic acid presented lower pH values than those
adjusted with citric acid, at the same concentrations.
The stability of B-aflatoxins in the sorghum was significantly
affected by the extrusion-cooking parameters, the
sample MC as well as acid concentrations (Fig. 2). The
highest reduction in the aflatoxin content (92%) was
observed in extrudates obtained with 30% MC and
8Æ0 mol l)1 citric acid. Under these conditions, the final
aflatoxin content was 11 pbb (Fig. 2, profile a). However,
only a 67% of aflatoxin reduction occurred with lactic
acid at the same extrusion conditions; these samples had
an aflatoxin content of 46 ppb (Fig. 2, profile b).
Discussion
The used techniques (MC, incubation temperature ⁄ time
and fungal spore load) worked as expected to obtain the
aflatoxin-contaminated sorghum. In relation to the spore
load in this cereal, there is no information available.