The decomposition of zearalenone, an estrogenic mycotoxin produced by Fusarium spp., during either heating of wheat-flour cake or cooking of foods including bread, instant noodles, and biscuit was studied. The effects of food additives such as ammonium persulfate and potassium carbonate on the decomposition were also investigated.
1) The decomposition of zearalenone spiked in wheat-flour cake was dependent upon heating time. At 100°C, about 10% of the toxin was decomposed, suggesting that the bulk of zearalenone present in foods may remain unaffected during usual cooking procedures of boiling and steaming. At 200°C the amount of toxin in the flour cake decreased linearly with heating time; 37% of the toxin was decomposed at 30min after the start of heating and 69% at 60min.
2) Upon treatment with either ammonium persulfate (0.03%) or kansui (1% potassium carbonate), about 30% of the toxin in the wheat-flour cake was decomposed during heating for 15min at 100°C. The levels of these additives were chosen according to the Standard of Food Additives of Japan. The extent of zearalenone decomposition at 15min after the start of heating at 200°C reached 34% with ammonium persulfate and 51% with potassium carbonate. The former rate was 4.5 times higher than that in the wheat-flour cake without any food additive, and the latter was 6.4 times higher.
3) With bread, instant noodles and biscuit, although 15% to 68% of zearalenone disappeared during processing, significant amounts of the toxin still remained in the foods.
4) In view of the significantly lower uterotropic activities of the heated wheat-flour cake and the bread, it is suggested that the decomposition product (s) of zearalenone does not retain significant activity.