Dielectric barrier discharge plasma processing: Impact on thiram fungicide degradation and quality of tomato juice

Abstract

Dielectric barrier discharge (DBD) plasma is a novel, nonthermal, eco-friendly technology with broader food processing and preservation applications. Also, it efficiently involves pesticide degradation and converts it into a nontoxic substance without influencing food quality. In the present study, we probed the effect of DBD plasma on thiram (TH) fungicide reduction in tomato juice, vita ascorbic acid, total phenolics, antioxidant activity, and microbial and enzymatic activity. DBD plasma processing was carried out at different voltages (40 and 45 V) for 3, 4, and 5 min. GC-MS analyzed the TH fungicide reduction. Results revealed that the maximum decrease in TH in tomato juice was 74.1% at 45 V for 5 min. While based on the proposed degradation pathway, the thiram fungicide reduction depends on the loss or rupturing of C═S, S–S, and C–N through hydrolysis and oxidation process and formed substances like N-dimethyl thiocarbamoyl disulfide, dimethyl dithiocarbamate, and methyl dimethyldithiocarbamate etc. Increased DBD plasma voltage and treatment time significantly reduced the TH concentration (p ≤ 0.05). In contrast, more than the untreated sample, DBD plasma treatments significantly reduce (p ≤ 0.05) the TFC, ascorbic acid, and ORAC assay. Regarding juice safety, DBD plasma prolonged the shelf life by reducing the pectin methyl esterase (PME) and total viable count from 23.12 to 11.24 mmol/min/g and 5.63 to 1.38 log CFU/mL. From a future food industry perspective, DBD plasma processing can reduce organic residues (fungicides) and improve self-life.

Keywords

• DBD plasma
• Thiram fungicide
• Phenolics
• Microbial
• Enzymatic