Roelf Bernhard Meima

Reduction of acrylamide formation in bakery products by application of Aspergillus niger asparaginase.

ABSTRACT The presence of acrylamide in a number of fried and oven prepared foods was published recently and has caused world-wide food safety concerns. Acrylamide is a well-known neurotoxin and considered as a probable carcinogen for animals and humans. Its presence was especially demonstrated in food products of plant origin, including baked or fried potato products and bakery products. Previous studies have shown that acrylamide is formed from L-asparagine at food processing temperatures exceeding 120°C. Hence, in bread products acrylamide is mainly found in the crust at levels of up to 230 ppb. In the crumb hardly any acrylamide was detectable because the temperature does not exceed 100°C during baking. Furthermore, the choice of the flour, the addition of sugar, and the baking temperature affected the formation of acrylamide in the crust. As expected, the addition of L-asparagine to the dough strongly stimulated acrylamide formation. Since acrylamide is formed from L-asparagine, the idea occurred to convert L-asparagine in dough before the actual baking process in order to prevent acrylamide formation. For that purpose, a gene coding for asparaginase was cloned from the foodgrade organism Aspergillus niger and expressed in its native host. The resulting strain was fermented, and the asparaginase was subsequently purified and added to dough. This resulted in a significant reduction in acrylamide level in bread crusts. In Dutch honey cake, for example, a reduction of more than 95% was obtained.