Effects of nitrogen dioxide fumigation on spoilage microorganism in stored products

Authors: Oh, Sookyung; Singh, Rippy; Liu, Yong Biao

Submitted to: Methyl Bromide Alternatives and Emissions Research Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 8/20/2020
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Nitric oxide (NO) is a new fumigant for postharvest pest control. NO fumigation is performed in ultralow oxygen (O2) conditions, because NO reacts with O2 spontaneously, resulting in the production of nitrogen dioxide (NO2). By adjusting O2 concentrations in the fumigation chamber, NO fumigation can also be conducted with desired levels of NO and NO2. NO2 has microbicidal effects. We investigated the effect of NO2 fumigation on Aspergillus flavus fungal spores and microorganisms in unpasteurized almond kernels and unpasteurized unshelled peanuts. Fumigation with 0.1% NO2 was effective to control A. flavus spores on nitrocellulose membrane filters in 3 hours at 15°C. Almonds and unshelled peanuts were fumigated with 0.1%, 0.3%, and 1.0% NO2 for one and three days at 25°C. Pasteurized unshelled peanuts were inoculated with A. flavus spores, cultured for over one month, and were then fumigated. Wash-off samples of almonds and peanuts from treatments and controls were analyzed using a rapid enumeration test to determine microbial loads and effectiveness of fumigation treatments. NO2 fumigation treatments greatly reduced microbial loads on almonds and peanuts and effectively inhibited the growth of A. flavus in infected peanuts. These results suggested that NO2 fumigation has strong antimicrobial effects on stored products, and fumigation with desired levels of NO and NO2 has potential to control pests and spoilage microorganisms.