does not derive from a more or less incomplete extraction with
aqueous-organic solvents but from the fact that the AC in the
residues of the extracts is not taken into account (Pe´ rez-Jime´nez
and Saura-Calixto, 2005). When the residues undergo acidic
hydrolysis, the AC value in the hydrolysates will be high. This AC is
mainly derived from the polyphenols (including ferulic acid)
released by the cell wall or DF matrix. This AC may be even higher
than the AC found in the aqueous-organic extracts. Table 2 shows
AC in extracts (AC1) and residues (AC2) of some cereals; note that
AC2 is significantly higher than AC1 in these samples; this suggests
that the actual total AC of cereals would be AC1 plus AC2. Most
literature data consider just AC1.