Cloning and Expression of Acetaldehyde Dehydrogenase from Archaea and Its Application in Acrylamide Elimination from Fried Foods

High-temperature frying is a common food processing method, and fried foods are favored by consumers due to their unique flavor and good taste. However, the degradation of unsaturated fatty acids in fats and oils during high-temperature processing results in the production of toxic lipid hydroperoxides (LOPs), saturated and unsaturated aldehydes, as well as acrylamides, which have been classified as group I carcinogens by the International Agency for Research on Cancer (IARC). In this study, high-temperature acetaldehyde dehydrogenase (SufALDH) of marine thermophilic archaeon Sulfolobus tokodaii 7 cloned and expressed. The optimal temperature was 88 °C and the optimal pH was 8.0. The SufALDH enzyme was further used for the pretreatment of fried food, which led to significant reduction in the aldehyde content of the fried food. In SufALDH-treated French fries, fried chicken, and fried fish, aldehyde content was reduced by 60%, 52%, and 33%, respectively, while 40% reduction in acrylamide was observed in the French fries treated with SufALDH. Molecular docking indicated seven key amino acid residues between SufALDH and substrate acetaldehyde, acrolein, acrylamide, and isopropyl alcohol, and they will be mutated to improve the SufALDH characteristics for its further application in food industries.