Dehydrotriferulic and Dehydrodiferulic Acid Profiles of Cereal and Pseudocereal Flours

Dehydrooligomers of ferulic acid cross-link polysaccharides such as arabinoxylans and pectic polysaccharides in cereal and certain pseudocereal grains, affecting physiological effects of these fiber components and their physicochemical properties during food processing. An HPLC-MS method for the analysis of eight diferulic acids and five triferulic acids in low-lignin samples such as cereal grains and pseudocereals was developed and validated. This method was applied to the analysis of ester-linked diferulates and triferulates in maize, popcorn, wheat, rye, oats, barley, buckwheat, and amaranth, giving a complete profile of this set of diferulates and triferulates in cereals and pseudocereals. Triferulic acid contents of the cereal flours are roughly 1/10 of the diferulic acid contents, ranging between 23 (oats) and 161 (popcorn) mu g/g of flour, with lower amounts for the pseudocereal flours (1-3 mu g/g of flour). Dominating trimers are either the 5-5/8-O-4- and/or the 8-O-4/8-O-4-regioisomers with lower proportions of 8-8cyclic/8-O-4-, 8-5noncyclic/8-O-4-, and 8-5noncyclic/5-5-triferulic acids. A unique diferulate pattern was found for buckwheat, with more than 90% of the dimers being 8-5-coupled. Amaranth contains an unusually high proportion of 8-8cyclic-diferulate, with 27% of the total dimers, whereas oats and barley show comparably high proportions (23%) of the 8-8tetrahydrofuran diferulate.