Quebec researchers use irradiation and important oil vapours to guard saved grains


Combining irradiation with essential oil vapors can effectively destroy insects, bacteria and mold in stored grains. A team from the National Institute for Research (INRS) in Quebec, led by Professor Monique Lacroix, has demonstrated the effect of this process on insects in rice. The study was published in the journal Radiation Physics and Chemistry.

Currently, the food industry uses fumigants to destroy microorganisms and insects in stored grains. However, these compounds, which evaporate or decompose into gases in air or water, pose a threat to human health and the environment. “When grain is fumigated, a small amount of gas is absorbed by the grain and released into the atmosphere. When irradiating food, the treatment is physical. When “new molecules” are produced, they are no different from those produced by normal processes on food such as heat, ”says Professor Monique Lacroix.

Food irradiation refers to the exposure of food to ionizing radiation, including gamma rays and X-rays. The research team has determined the effectiveness of these two processes with and without essential oils.

Increase in radiation sensitivity

The aim of the study was to test whether the energy level of the variable flow rate irradiation source can affect the dose (or treatment time) required to kill 90% of insects or molds. The research team showed that gamma rays are more effective against insects than X-rays. In addition, a higher dose rate with gamma rays was found to be more effective than a lower dose rate.

In addition, adding eucalyptus and tea tree essential oils significantly improved its effectiveness. “With the addition of essential oils, the required dose was four to six times lower, depending on the gamma dose rate. In fact, oils make insects more sensitive to radiation, ”says Professor Lacroix.

Similar results can be observed for bacteria and mold, although they are more resistant to radiation. An earlier study found that adding thyme and oregano essential oils increased the sensitivity of microorganisms to radiation by 1.5 times.

The team also conducted experiments on essential oil vapors that had diffused in 5 kg bags of rice. In the future, the team would like to test the process in an industrial environment through partnership with companies.

About the study

The article “Radiosensitization of the rice beetle Sitophilus oryzae using combined treatments of essential oils and ionizing radiation with gamma and X-rays at different dose rates” by Farah Hossain, Peter Follett, Shiv Shankar, Tofa Begum, Stephane Salmieri and Monique Lacroix was published in the journal Radiation Physics and Chemistry published. The study received funding from the Canadian Science and Engineering Research Council (NSERC), the Department of Business and Innovation, and the United States Department of Agriculture (USDA).

About INRS

INRS is a university devoted exclusively to university-level research and education. Since its inception in 1969, INRS has played an active role in the economic, social and cultural development of Quebec, and has been at the fore in terms of research intensity in Quebec and Canada. INRS consists of four interdisciplinary research and training centers in Quebec City, Montreal, Laval and Varennes with expertise in strategic sectors: Eau Terre Environnement, Énergie Matériaux Télécommunications, Urbanization Culture Société and Armand-Frappier Santé Biotechnologie. The INRS community includes more than 1,500 students, postdocs, faculty members, and staff.