Effects of formulation, extrusion cooking conditions, and CO₂ injection on the formation of acrylamide in corn extrudates

Background: Acrylamide is a possible carcinogen and known to form in heat-treated carbohydrate-rich foods. This study was designed to investigate the effects of different ingredients (reducing sugars, chemical leavening agents, citric acid), processing conditions (feed moisture content: 22, 24 or 26%, exit die temperature: 110, 150 °C), and extrusion cooking methods (with or without CO2 injection) on acrylamide formation.

Results: The type of reducing sugar did not have a considerable effect on acrylamide formation, while increased exit die temperature had a promoting effect. Addition of chemical leavening agents (sodium bicarbonate and ammonium bicarbonate) into formulations increased acrylamide formation levels. The addition of citric acid prevented acrylamide formation, but its effect on textural properties was detrimental. Acrylamide levels of extrudates decreased gradually with increasing feed moisture in all formulations. Acrylamide content of extrudates produced with 22% feed moisture decreased by 61% in the CO2 injection method compared to conventional extrusion. Furthermore, an 82% decrease in acrylamide content was observed with the combined effect of CO2 injection and increasing feed moisture content from 22 to 24% and decreased below the limit of quantification with a further increase in feed moisture.

Conclusion: A substantial decrease in final acrylamide level is probably due to restriction of two major steps of acrylamide formation: dehydration and decarboxylation.