Extension of Tomato Shelf Life via Nitric Oxide Treatment Using Air Plasma

Nitric oxide (NO) generation-enhanced atmospheric-pressure plasma technology has been investigated as a nonthermal intervention technology for prolonging the ripening period of tomatoes. UV-irradiated dielectric barrier discharge plasma reaches the NO-enhanced mode earlier, and NO is rapidly involved in the inhibition of tomato respiration. With as little as 26 W of power in total, the NO-processing of tomatoes using plasma technology helps control the postripening of tomatoes. The NO-enrichment mechanism was analyzed through numerical calculations, which revealed that the photolysis of ozone (O-3) and nitrous acid (HONO) occurred during UV irradiation. The measured amount of CO2 emitted from plasma-treated tomatoes was similar to 300 ppm lower than that emitted from nontreated tomatoes, indicating that metabolism and respiration were inhibited. In addition, the NO-enhanced plasma treatment of tomatoes is considered to be more effective because the so-treated tomatoes emitted 100 ppm less CO2 than the plasma-treated tomatoes. The delay of respiration through plasma treatment can help prevent color changes or decreases in the firmness of tomatoes.