Residual analysis of nitric oxide fumigation on fresh fruit and vegetables

Authors: YANG, XIANGBING - University Of California; Liu, Yong Biao

Submitted to: Postharvest Biology and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/15/2017
Publication Date: 6/20/2017
Citation: Yang, X., Liu, Y.-B. 2017. Residual analysis of nitric oxide fumigation on fresh fruit and vegetables. Postharvest Biology and Technology. 132:105-108.

Interpretive Summary: Nitric oxide is a newly discovered fumigant for postharvest pest control. As nitric oxide reacts with oxygen to produce nitrogen dioxide, nitric oxide fumigation must be conducted under ultralow oxygen conditions. In this study, residues of nitric oxide fumigation were analyzed on 20 fresh fruit and vegetables to determine whether nitric oxide fumigation can affect food safety and to collect necessary data for registration of nitric oxide with US EPA in the future. Each fresh product was subjected to two identical fumigation treatments that were severer than needed to control most target insect pests on the product. However, one treatment was terminated with nitrogen flush to dilute nitric oxide before exposing products to ambient air and the second treatment was terminated with air flush to deliberately allow nitric oxide to react with oxygen to produce nitrogen dioxide and thereby maximize possible residues on products. Residues in forms of NO2 in headspace, NO3- and NO2- in liquate samples were measured at 24 h after fumigation. Emissions of NO2 after fumigation were also measured over time. NO2 levels from fumigated products declined dramatically over time. At 24 h after fumigation, for most product NO2 emission for the treatment flushed with nitrogen was the same as the controls and there were also no elevated NO3- or NO2- for the treatment. The treatment terminated with air flush, however, had elevated NO3- in some products. This study indicated that nitric oxide fumigation when terminated properly did not alter NO3- or NO2- levels in fresh products and did not have any safety concern.

Technical Abstract: Nitric oxide (NO) is a newly discovered fumigant which is effective against a wide range of postharvest pests. To register NO with US EPA for commercial use as a pesticide and to ensure its safety to consumers, it is necessary to analyze residues of NO fumigated products. In this study, we analyzed the NO2 emission rate, nitrate (NO3-), and nitrite (NO2-) concentrations as residues in headspace and aqua extracts of 20 fresh products at 24 h after 16 h fumigation treatments. Each product was subjected to two identical NO fumigation treatments except one treatment was terminated by flushing with N2 and the other terminated by flushing with air. For most products, there were no significant differences among the treatments in NO2 emission rate, NO3- level, and NO2- level. However, apple and garlic from NO fumigated flushed with air had significantly higher NO2 emission rate. NO2- concentration was generally not detectable in both fumigated and control products. Furthermore, NO2 emission rate in all fumigated products declined to acceptable levels like control at 5 to 8 h after fumigation. Only when NO fumigation treatment was terminated by normal air flush, significantly higher NO2 emission rate, NO3-, and NO2- concentrations were found in all fumigated products than both control and N2 flushed fumigated products. Therefore, our results indicated that there were no significant levels of residues from NO fumigated fresh products at 24 h after fumigation when fumigation was terminated properly.