To my knowledge ultrasonification might speed up chemical reactions but not induce new ones to occur. Changing the structure of the aflatoxin molecules does not necessarily mean that they will be less toxic or carcinogenic. Intermediates are believed to be be more reactive and might cause more problems than the parent compounds.

The (food) material containing the aflatoxins must be harshly treated in order to extract them. Thus the original structure will be totally gone and its nutritive value also is quite questionable.

So I always advocate prevention as trying to solve the problem afterwards might sometimes be technically possible, but rarely economically feasible.

The structures of aflatoxins are highly stable and their complete removal is difficult and might be possible some 10-20 % reduction. I have use gamma radiation for aflatoxins in red chilies and found effective.