Work

Unraveling the Reactive Oxygen and Nitrogen Species Responsible for Oxidation of Methionine, Cysteine, Tyrosine and Tryptophan in Atmospheric Pressure Nonthermal Plasma Treatment

Year: 2026

Type: article

Abstract: Nonthermal plasma is a promising food preservation method, yet its effects on proteins remains underexplored. In this study, aqueous solutions of methionine, cysteine, tyrosine and tryptophan at pH 4.75 were exposed to a multihollow surface dielectric barrier discharge using dry air, humid air (75% relative humidity) or Ar/O 2 (99/1%). Native amino acids and their degradation products were quantified using HPLC-FLD/DAD and LC–MS/MS. To identify key reactive species, the same amino acids were treated with individual reactive oxygen and nitrogen species (RONS; 1 O 2, O 3, H 2 O 2, • OH, O 2 NOOH, ONOOH, ONOOCO 2 –, OCl – ). Ozone emerged as the dominant oxidant across all plasma conditions, with nitrogen species also contributing. Amino acid sensitivity to plasma varied, with methionine and tryptophan showing higher oxidation (8–27%) than cysteine and tyrosine. Major oxidation products included methionine sulfoxide, cysteic acid, levodopa and N ′-formylkynurenine. These findings lay the groundwork for applying plasma technology to food protein treatment.

Source: Journal of Agricultural and Food Chemistry

DOI: 10.1021/acs.jafc.5c12473