Rice phenolic compounds include benzoic and hydroxycinnamic
acids, mainly ferulic acid and diferulates, whose concentrations
increase from the endosperm to aleurone (Zhou et al., 2004).
The most soluble compounds are compartmentalized within the
cell vacuoles, and they are in free form or conjugated, whereas
insoluble phenols are linked to cell wall structures, esterified with
arabinose and galactose residues of pectic or hemicellulosic components