A novel method for the selective extraction of free (pH 8.4) and total sulfite (pH 11.0) from muscle foods and the following determination by a voltammetric sensor was reported. The proposed method was based on the eletrocatalytic oxidation of sulfite at modified glassy carbon electrode (GCE) fabricated by immobilizing 9 μg of acetylferrocene on the surface of GCE along with 35 μg of carbon black to improve the electron transfer within poly(vinyl butyral) membrane matrix. The external standard calibration curve was linear in the range of 0.03–4.0 mmol L–1 with a detection limit of 15 μmol L–1. This method had been applied to the determination of free and total sulfite in shrimp muscle fortified samples and compared with an ion chromatography method. The proposed electrode and analysis methods were proven to be sensitive, accurate, and rapid and exhibited very good reproducibility and stability under the used conditions.
An interesting phenomenon that plasma-activated water (PAW) treatment reduced the malonaldehyde (MDA) content in muscle foods was observed in both previous reports and the present study. However, the mechanism remains unclear. To clarify the theoretical basis of this phenomenon, the main reactive components in PAW were determined, and the changes in the fatty acid profile in tuna muscle after PAW treatment were analyzed. The results showed that the MDA content reduction upon PAW treatment was not due to the inhibition of lipid oxidation. To mimic the possible reaction of the components in PAW with MDA, individual hydrogen peroxide, nitrite, and nitrate or their mixture solution were added into MDA standard and tuna muscle. The results showed that the reaction of nitrite in PAW with MDA occurred during its measurement processes caused its reduction. The results in this work fully explained why PAW treatment reduced the MDA content in muscle foods.
危险品化学品经营许可证（带存储）