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Prof. Shlomo Navarro Green Storage Ltd. Israel e-mail: snavarro@green-storage.co.il

Effects of modified atmospheres on insects with special reference to silo-bags. Prof. Shlomo Navarro Green Storage Ltd. Israel e-mail: snavarro@green-storage.co.il. Modified atmospheres and hermetic storage take advantage of the basic fact that.

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Prof. Shlomo Navarro Green Storage Ltd. Israel e-mail: snavarro@green-storage.co.il

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  1. Effects of modified atmospheres on insects with special reference to silo-bags Prof. Shlomo Navarro Green Storage Ltd. Israel e-mail:snavarro@green-storage.co.il Navarro - Effects of MA on insects in silo-bags

  2. Modified atmospheres and hermetic storage take advantage of the basic fact that Storage insects are aerobic organisms requiring oxygen for their survival Navarro - Effects of MA on insects in silo-bags

  3. Action of modified atmospheres on insects 1- Desiccation 2- Anoxia 3- Hypercarbia Navarro - Effects of MA on insects in silo-bags

  4. A moth larva with spiracles along the body Navarro - Effects of MA on insects in silo-bags

  5. What is hermetic storage? hermetic storage is a type of biogenerated MA It consists of generation of anoxygen-depleted andcarbon dioxide-enriched interstitial atmosphere by the respiration of the living organisms in the ecological system of a sealedstorage. Navarro - Effects of MA on insects in silo-bags

  6. Organisms that contribute to the generation of MAs • Insects and mites • Aerobic microflora • Anaerobic microflora • Seed germ Navarro - Effects of MA on insects in silo-bags

  7. <65% RH Insects & mites 65 to 85% RH Aerobic fungi, seed germ >85% RH Anaerobic bacteria Bio-generation of MAs in relation to the atmospheric gas composition and the humidity of their environment Aerobic conditions High oxygen Low carbon dioxide Anaerobic conditions Low oxygen High carbon dioxide Navarro - Effects of MA on insects in silo-bags

  8. First challenge in MA and hermetic storage Maintaining a well sealed storage structure Navarro - Effects of MA on insects in silo-bags

  9. Night Day Cooled air contracts Heated air expands Navarro - Effects of MA on insects in silo-bags

  10. Atmospheric pressure Navarro - Effects of MA on insects in silo-bags

  11. At high atmosphericpressure At low atmospheric pressure External atmosphere moves in Inside atmosphere moves out Navarro - Effects of MA on insects in silo-bags

  12. Parameters to determine GASTIGHTNESS of the structure 1- Leaks of the structure. Can be assessed using pressure test. 2- Permeability of the membrane, particularly in flexible structures. Should be measured in a laboratory. Navarro - Effects of MA on insects in silo-bags

  13. Second challenge in MA and hermetic storage Preventing permeation of oxygen through the flexible liners Navarro - Effects of MA on insects in silo-bags

  14. Oxygen permeability requirements [mL/(m2 24 h)] of liners in relation to various storage capacities (m3) and oxygen ingress rates (%/24 h) for successful application of hermetic storage of dry grain. Navarro - Effects of MA on insects in silo-bags

  15. Third challenge in MA and hermetic storage • Absorption and adsorption of carbon dioxide by the commodity C - Aeration period A – Carbon dioxide distribution B - Exposure period Navarro - Effects of MA on insects in silo-bags

  16. Recommended ranges for variable pressure test carried out in structures destined for gaseous treatments to control storage insects. < Variable pressure test decay time (min) 250 to 125 Pa Structure volume in cubic meters Type of gaseous treatment 95% Full Empty structure <500 3 1 5 . Fumigants 500 to 2,000 4 2 2,000 to 15,000 6 3 6 3 <500 Controlled atmospheres 7 4 500 to 2,000 1 1 6 2,000 to 15,000 1 0 5 <500 Modified atmospheres including airtight storage 1 2 6 500 to 2,000 1 8 9 2,000 to 15,000 Navarro - Effects of MA on insects in silo-bags

  17. 250 225 Exposed 200 Shaded 175 150 PH3 loss (ppm/day) 125 100 75 50 25 0 1 2 3 4 5 6 Minutes for half-life pressure decay Phosphine loss from an empty structure of 7.5 m3 capacity in relation to half-life pressure decay time. Phosphine loss should not exceed 100 ppm/day. Navarro - Effects of MA on insects in silo-bags

  18. Fourth challenge in MA and hermetic storage Liner durability: Insect damage Rodent damage Weather damage, mainly UV. Mechanical damage Navarro - Effects of MA on insects in silo-bags

  19. Low O2 ingress level, is difficult to maintain in rigid structures, but is achievable in practice using flexible liners Navarro - Effects of MA on insects in silo-bags

  20. Measured CO2 concentration during storage time of three silo-bags with soybeans at 11.5%, 12.9% and 14.9% m.c. and average ambient temperature (adapted from Bartosik, 2008). Navarro - Effects of MA on insects in silo-bags

  21. Calculated O2 and CO2 concentration in silo-bags containing wheat of initial m.c. at 12, 14 and 16% w.b. for locations at Saenz Peסat Pergamino and Balcarce. Initial temperature 25oC (adapted from Baretto et al., 2012). Navarro - Effects of MA on insects in silo-bags

  22. Application of BIOGENERATED atmospheres on dry cereal grain Navarro - Effects of MA on insects in silo-bags

  23. The process of hermetic storage Residual oxygen within the hermetic storage Critical point Insect respiration Oxygen ingress rate 0.05 %/day Navarro - Effects of MA on insects in silo-bags

  24. Modified atmosphere generated by respiration of insects in hermetic storage (calculated theoretical). Based on grain mass containing different infestation levels of insects with an oxygen ingress raאe ofO.24%/day. Navarro - Effects of MA on insects in silo-bags

  25. Calculated weight-loss from a grain mass containing initial infestation of 2 insects/kg, at different oxygen ingress rates. Target gastightness level Navarro - Effects of MA on insects in silo-bags

  26. Target gas tightness to control storage insects in dry cereals, in hermetic storage structures Daily oxygen ingress rate: 1- Below 0.05 % O2/day prevents oscillated oxygen concentration and increased weight loss. 2- Between 0.05 and 0.24 % O2/day allows oscillated oxygen concentration and increased weight loss. Navarro - Effects of MA on insects in silo-bags

  27. Conclusions • MA or hermetic storage are very promising qualitypreservation and insect control technologies. • There are a number of challenges in the application of MA or hermetic storage: • Maintaining a well sealed storage structure. • Preventing permeation of gas through the structural membrane (by improved liners). • Consider absorption and adsorption of carbon dioxide by the commodity. • In flexible storages improve liner durability; to insect damage; to rodent damage; to weather; and to mechanical damage. • For silo-bags daily oxygen ingress rate should be below 0.10 % O2/day. • For silo-bags oxygen permeability requirements of liners should be below 400 [mL/(m2 24 h)] Navarro - Effects of MA on insects in silo-bags

  28. Thank you for your attention !!! Silobags for sealed storage of grain Navarro - Effects of MA on insects in silo-bags

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