Skip to main content
ARS Home » Plains Area » Manhattan, Kansas » Center for Grain and Animal Health Research » Stored Product Insect and Engineering Research » Research » Publications at this Location » Publication #314055
Title: Cold temperature disinfestation of bagged flour

Author
item FLINN, PAUL - Retired ARS Employee
item Arthur, Franklin
item Throne, James
item Friesen, Kenlee - Ken
item Hartzer, Kris

Submitted to: Journal of Stored Products Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/12/2015
Publication Date: 6/23/2015
Publication URL: http://handle.nal.usda.gov/10113/61725
Citation: Flinn, P.W., Arthur, F.H., Throne, J.E., Friesen, K.S., Hartzer, K.L. 2015. Cold temperature disinfestation of bagged flour. Journal of Stored Products Research. 63:42-46. doi: 10.1016.j.jspr.2015.06.001.

Interpretive Summary: Cold temperatures will kill stored product insects but there is little practical information on how they can be used to eliminate infestations in finished products. We used a pallet of stacked flour bags to determine cooling patters in the center bags versus the peripheral bags. We also exposed red flour beetle eggs in the center bags and in the peripheral bags. As expected it took longer for the bags in the center of the pallet to cool than the peripheral bags. However, no beetle eggs survived at temperatures of 39°F or less in the center bags. For the 32°F temperature goal treatment, it took 24 days for the temperature in the center bag to go from 70°F to 32°F and back up to 70°F. This relatively long exposure to low temperatures results in 100 % egg mortality. The fact that the treatment only required 5.5 days in the freezer before it could be shipped makes it a practical method to disinfest pallets of flour. Results will benefit flour mill managers by providing guidelines to more effectively use cold temperatures as a disinfestation strategy.

Technical Abstract: We conducted studies using a commercial freezer maintained at -17.8°C to determine the time needed to kill Tribolium castaneum eggs in a pallet of flour. Each bag weighed 22.7 kg, and there were 5 bags in each of 10 layers. The dimensions of the pallet were 109-cm wide by 132-cm long by 123-cm tall, and the weight of the stacked pallet was approximately 1,152 kg. We conducted tests for nine internal goal temperatures of -12, -10, -8, -6, -4, -2, 0, 4 and 8°C. Internal temperatures in the most central location of the flour pallet reached: -11.0, -9.4, -6.9, -5.0, -3.5, -1.6, -0.1, 3.3, and 5.6°C and were achieved after 11.0, 9.1, 8.9, 7.2, 6.7, 5.8, 5.5, 5.2, and 4.2 days, respectively. For treatments where the goal temperature for the center bag ranged from -12 to 4°C, egg mortality was 100 % in bags located in both the periphery and in the center of the pallet. When the temperature goal for the center bag was 8°C, 7±2.5 % of the eggs survived in bags located near the center of the pallet. Our data showed that temperatures that follow the dynamic temperature curve that takes place over 24.2 days (cool down and warm up for the 0°C temperature goal) resulted in 100 % mortality of T. castaneum eggs. The reason for the difference in mortality for a static compared to a dynamic temperature treatment may be due to the fact that the dynamic temperature treatment occurs over a much longer duration. For the zero temperature goal treatment, it took 24 days for the temperature in the center bag to go from 21°C to 0.1°C and back up to 21°C. This relatively long exposure to low temperatures results in 100 % egg mortality. The fact that the treatment only required 5.5 days in the freezer before it could be shipped makes it a practical method to disinfest pallets of flour, especially because the flour does not need to be removed from the bags and no chemicals are used.