The effect of non-thermal plasma on the lipid oxidation and microbiological quality of sushi

The study examined the effect of non-thermal plasma (NTP) on the total viable count and lipid oxidation of two common sushi products: nigiri and hosomaki. Sushi samples were treated with NTP using a dielectric barrier discharge system with 70 and 80 kV of potential differences for 5 min. The samples were stored at 4 °C for 11 days and analysed for total aerobic count, moisture and protein content, TBA index and fatty acids composition. Although the effect of NTP on the total aerobic counts was not statistically significant, a tendency in log reduction could be observed, with 1-1.5 log cfu/g reduction. Moisture and protein content, as well as fatty acids composition of sushi was not affected by the treatment. The TBA index of treated samples increased significantly by 0.4-1.5 mg/kg, with hosomaki reaching higher TBA index than nigiri. Although NTP in the studied conditions can, to a limited degree, increase the microbiological quality of the sushi samples, it also increases the oxidation rate.