Potential of Hyperthermophilic L-Asparaginase from Thermococcus sibiricus to Mitigate Dietary Acrylamide Assessed Using a Simplified Food System

The Maillard reaction is a network of interconnected interactions yielding in formation a number of toxic derivatives in processed foods. Acrylamide, a potential carcinogen and a product of the Maillard reaction, is formed under food processing, predominantly from asparagine and reducing sugars at temperatures over 120 &deg:C. In this study, we investigated the potency of recombinant hyperthermophilic L-asparaginase from Thermococcus sibiricus TsAI to mitigate dietary acrylamide by hydrolyzing substrate for its synthesis under various operation conditions. Using a simplified food system for self-cooking, high acrylamide levels were found in baked samples regardless of whether L- or D-enantiomer of asparagine was added. TsAI effectively reduced acrylamide content under various pretreatment conditions, such as temperature, concentration, and time of incubation. The lowest acrylamide level of 1.0&ndash:1.1% of the control values or 3.52&ndash:3.76 &micro:g/kg was observed in samples pretreated with TsAI 20 U/mL at 90 &deg:C for 20&ndash:25 min. Due to the exceptionally high D-asparaginase activity of hyperthermophilic TsAI, the dietary acrylamide content formed from D-asparagine was reduced by 54.8% compared to the control. Comparison of the wild-type TsAI and its mutant reveal that an enzyme displaying enhanced stability is more functional for food-processing application. The native TsAI decreased acrylamide level by 98.9%, while the highly active mutant, with increased structural flexibility, decreased it by only 26.8%. TsAI treatment effectively blocked acrylamide synthesis, but not melanoidin formation via the Maillard reaction, thus not affecting sample characteristics such as color (browning) and aroma, which are important for consumer perception.