Processing contaminants may be defined as substances that are produced in a food when it is cooked or
processed, are not present or are present at much lower concentrations in the raw, unprocessed food, and
are undesirable either because they have an adverse effect on product quality or because they are
potentially harmful. The presence of very low levels of processing contaminants in common foods is
becoming an increasingly important issue for the food industry, as developments in analytical techniques
and equipment bring foods under closer and closer scrutiny. This review considers the formation of lipid
oxidation products, hydrogenation of polyunsaturated fatty acids to prevent lipid oxidation and the
associated risk of trans fatty acid formation. The formation of acrylamide in the Maillard reaction is
described, as well as the genetic and agronomic approaches being taken to reduce the acrylamideforming
potential of cereal grain. The multiple routes for the formation of furan and associated chemicals,
including hydroxymethylfurfuryl, are also described. The evolving regulatory and public perception
situations for these processing contaminants and their implications for the cereal supply chain are
discussed, emphasising the need for cereal breeders to engage with the contaminants issue.