Development of Nanocomposite Bioactive Diffusion Films (BDFs) Combined With Gamma Irradiation for Control of the Rice
Tofa Begum1, Peter A Follett2, Stephane Salmieri1
1Armand-Frappier Health Biotechnology Research Centre, Institut National de la Recherche Scientifique (INRS), Research Laboratories in Sciences, Applied to Food (RESALA), MAPAQ Research Chair in stabilized natural antimicrobial compounds, Food Safety and Quality, Canadian Irradiation Center (CIC), International Atomic Energy Agency (IAEA) Collaborating Centre, Institute of Nutrition and Functional Foods (INAF), Laval, Canada.
Abstract:
The fumigant toxicity of 6 essential oils (EOs) (Mediterranean, Southern, citrus, cinnamon, Asian, and savory thyme), 2 citrus extracts (CEs: organic OCE and natural NCE), and 2 active formulations (microfluidized nanoemulsions AF-1 and AF-2) was investigated for control of rice weevil (Sitophilus oryzae), a stored product pest. In bioassays, AF-1 and AF-2 at 0.6 µL/mL exhibited higher insecticidal efficacy compared to single EOs and CEs after 72 h of exposure. AF-2 showed higher acetylcholinesterase enzyme inhibition in rice weevils than AF-1. Oil-in-water nanoemulsions (NEs) of AF-1 and AF-2 were prepared by microfluidization, resulting in a decrease in droplet size (DS) from 232 to 116 nm and 230 to 40 nm, and an increase in encapsulation efficiency (EE) from 30% to 77% and from 11% to 79% respectively. To exploit the insecticidal attributes of these NEs, 6 nanocomposite bioactive diffusion films (BDFs) were prepared based on chitosan (CH), poly(butylene adipate-co-terephthalate (PBAT), or polylactic acid (PLA), all reinforced with cellulose nanocrystals (CNC), and containing either AF-1 or AF-2. Films were evaluated as diffusion devices in bags of rice infested with weevils. CH films induced the highest insect mortality (78%-83%) after 14 days, compared to 6% in controls. Gamma irradiation at 200 Gy alone caused 62% mortality, which increased to 82%100% after combination with the BDFs after 14 days. The presence of CNC in BDFs reduced the % release of bioactive NEs by 12%-27% compared to the films without CNC. PRACTICAL APPLICATIONS: Nanocomposite BDFs developed in this study could be applied as diffusion devices of insecticidal natural compounds for the control of rice weevils in packaged rice. The active formulations (AF-1 and AF-2 based on nanoemulsions of CEs and EOs), combined with low-dose irradiation treatments, could be used in the food industry for controlling insect proliferation in the sector of stored cereals.
