Effect of radiofrequency heating on acrylamide formation

The formation of significant levels of the suspected carcinogen acrylamide in carbohydraterich foods subjected to intense heating (e.g. baking and frying) has been widely reported. Although it has been demonstrated that acrylamide is formed from the reaction between free asparagine and intermediates of the Maillard reaction, the mechanisms at the basis of the development of this substance are still not fully understood. Results have shown that the kinetics of acrylamide formation are affected both by intrinsic factors of the food product, such as reducing sugar and amino acid concentration, chemical composition, water content, pH, physical state, etc., and process parameters (heating time and temperature). Due to the complexity of influencing factors, up today it was difficult to draw up guidelines to reduce acrylamide formation in foods. From a technological standpoint, the preliminary and general suggestions are relevant to the adoption of thermal treatments other than frying or prolonged cooking, which however are responsible for a decrease in the food sensorial acceptability. Radiofrequency heating is a promising technology for food applications, characterised by rapid and uniform heat distribution, large penetration depth and low energy consumption. It is generally applied as a post-baking operation to rapidly reduce the residual moisture of bakery products from about 6% to 3%. Although the acrylamide levels in baked products (breads, cakes, cookies, etc.) greatly vary with formulation and processing conditions adopted, the amounts reported are quite high, generally of the order of 200-500 ppb. The aim of the present study was to investigate the effects of radiofrequency heating on acrylamide formation in bakery products. Leavened cakes were obtained from a commercial ready-to-cook formulation. Cooking was carried out by using both conventional and radiofrequency (RF) heating. Products having different moisture levels were analysed for acrylamide content and colour properties Results showed that acrylamide formation was affected by the mechanism of heat transfer, i.e. conduction or dielectric heating.