Biochemical Characterization of Thermostable Acrylamide Amidohydrolase from Aspergillus fumigatus with Potential Activity for Acrylamide Degradation in Various Food Products

Abstract

Acrylamide is the major by-product of the Maillard reactions in foods with the overheating processes of L-asparagine-rich foods with reducing sugars that usually allied with neurotoxicity and carcinogenicity. Several approaches have been used to prevent the formation of acrylamide, however, degrading the already formed acrylamide in foods remains unequivocal. Acrylamide hydrolyzing enzyme “amidohydrolase” is one of the most promising enzymes for acrylamide degradation in foods. So, amidohydrolase “amidase” from thermotolerant Aspergillus fumigatus EFBL was purified to their electrophoretic homogeneity by gel-filtration and ion-exchange chromatography, with overall purification folds 2.8 and yield 9.43%. The apparent molecular subunit structure of the purified A. fumigatus amidase was 50 kDa, with highest activity at reaction temperature of 40 °C and pH of 7.5 The enzyme displayed a significant thermal stability as revealed from the value of T1/2 (13.37 h), and thermal denaturation rate (Kr 0.832 × 10–3 min) at 50 °C, with metalloproteinic identity. The purified enzyme had a significant activity for acrylamide degradation in various food products such as meat, cookies, potato chips, and bread as revealed from the HPLC analysis and LC–MS analysis. So, with the purified amidase, the acrylamide in the food products was degraded by about 95% to acrylic acid, ensuring the possibility of using this enzyme in abolishing the toxic acrylamide in the foods products. This is the first report exploring the potency of A. fumigatus amidase for an actual degradation of acrylamide in foods efficiently. Further biochemical analyses are ongoing to assess the affinity of this enzyme for selective hydrolyses of acrylamide in foods, without affecting the beneficial stereochemical related compounds.