 The 8-O-4'-DiFA tends to predominate in grasses, but 5,5'-DiFA predominates in barley bran.Rye bread contains ferulic acid dehydrodimers.In chufa (tiger nut, "Cyperus esculentus") and sugar beet the predominant diferulic acids are 8-O-4'-DiFA and 8,5'-DiFA respectively.