Acrylamide in oat products : a literature survey

Abstract: Acrylamide can be formed during heating of cereals. Oats have the second highest acrylamide forming potential of rye, wheat, barley and oats. Several studies have found high levels of acrylamide in oat products that exceed the benchmark limits within the EU. These limits might be strict limits in future which every food producer needs to follow. Reactions between reducing sugars and free asparagine is the major contribution of acrylamide in food. Free asparagine is not incorporated into proteins and might thus easily react in the Maillard reaction and form acrylamide. It has been shown that free asparagine is the determining factor for acrylamide formation in cereals. Free asparagine accumulates in cereals when there is an excess of nitrogen and at the same time a deficit of sulphur. Proper fertilising and selection of crops with low levels of free asparagine might be the key to lower acrylamide formation in oat products. During processing, salts, other amino acids than asparagine and asparaginase may be added to lower acrylamide formation in various baked products. Some of these additives and especially salts have however bad impacts on health as well as product quality. Acrylamide formation is also affected by pH, where a higher pH produces more acrylamide. Antioxidants might inhibit acrylamide formation, but some studies have found the opposite and theorises that some antioxidants prevent further reaction of acrylamide with other compounds. It is known however that antioxidants can in-hibit lipid oxidation and by extension lower the formation of acrylamide, since some lipid oxidation products such as acrolein might react with asparagine. Longer fermentation time of yeast doughs have been shown to produce bread with a lower acrylamide level since the yeast consumes the free asparagine. Sourdough as leavening agent is not as effective at consuming asparagine, probably due to compe-tition from bacteria that impairs the yeast in the sourdough. If sourdough is to be used it is however better to use one based on oat or barley compared with rye or wheat flour since bread baked on oat or barley sourdoughs has been shown to have the low-est acrylamide content. Acrylamide formation occurs in oat products, but the process is not as well studied as in other foodstuffs and more research is needed. This report aims therefore to list mitigation strategies to lower acrylamide formation in oat products.