Pulsed electric fields act on tryptophan to inactivate α-amylase

Abstract

Abstract Enzyme inactivation is a common industrial step of food preservation. Conventional method is based on heating, thus reduce organoleptic property and virtues of the products. We propose a non-thermal method of enzyme inactivation based on pulsed electric fields. By comparing the effect of electric fields, heating and oxidation on alpha-amylase, we have shown that the electric field targets the active site of the enzyme via the tryptophan, resulting in a conformational disruption. An electric pulse of 2.5–12.5\xa0kV/cm, 10 μs and 0.02–0.6\xa0J, repeated at 1–30\xa0Hz for a total applied energy of 1440 J, partially denatured alpha-amylase, reducing activity by up to 70%; however, this was not followed by protein aggregation, as observed for heat treatment to 70\xa0°C. Those results brought new understanding on the mechanism of pulsed electric fields action on proteins, and might lead in new application in food industry or in medicine.