Within the bread crust, a number of phenolic acids were not detectable. This may be due to interactions with Maillard reaction adducts or thermal degradation. Phenolic acids have been demonstrated to react, via redox reactions, with intermediates of the Maillard reaction forming phenolic acid-Maillard adducts (Jiang and Peterson, 2010). As the bread crust has more favourable conditions for the Maillard reaction to occur than in crackers, including moisture, pH and processing conditions (Capuano et al., 2008) the reaction of phenolic acids with Maillard intermediates may be a plausible reason as to why phenolic acids were not detected within the bread crusts, but detectable within crackers.