Abstract.Chilled aeration allows grain to be cooled, independent of ambient conditions, to “safe” temperatures at which insects, fungi, and spoilage development are reduced to a minimum. The objective of this research was to evaluate the advantages of using grain chilling to preserve the quality of grain and reduce post-harvest losses caused by insects and fungi, compared to the conventional aeration and storage strategies used during summer storage in central Kansas. The research trials were developed at a farmer’s cooperative in central Kansas in 2015 and 2016 on low-moisture wheat harvested during the summer of 2015 and 2016, respectively, and stored in two 1,350 metric ton (t) steel silos in which one was chilled and the other was used as a control managed by the cooperative. Temperature of the grain inside each silo was monitored with temperature cables. Variables evaluated were: moisture content (MC), grain and flour quality, insect-pest development and reproduction rate, insect fragments per 500 g of grain, and fungi presence. In 2015, the chilling treatment reduced the grain temperature from 28°C to 17°C in approximately 175 h, while in 2016 it took 245 h to reach about the same temperature with an initial grain temperature of 39°C. Grain temperatures below 25°C were not achieved in the control silo during the summer using ambient aeration. Minimum variation of MC was observed in the Chilled silo while ambient aeration reduced the moisture content by 0.5%. Reproduction rates of the red flour beetle and lesser grain borer were significantly reduced by chilling temperatures lower than 17°C. Lower temperatures also reduced insect populations detected in probe traps and insect damaged kernels. Insect fragments and fungi presence had no significant increase throughout the trials in either of the silos. No clear evidence of flour quality being better preserved at lower temperatures was detected. The energy cost of running the grain chiller was between 0.26-0.32 $/t higher than ambient aeration. Keywords: Ambient aeration, Grain chilling, Grain quality, Stored-product fungi, Stored-product insects, Summer storage, Wheat.

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Chilling aeration of stored grain is becoming very popular around the world since it offers many advantages in situations where ambient air conditions are not adequate to cool grain. It allows to cool grain, independent of ambient conditions, to "safe" temperatures where insect, fungi, and spoilage development is reduced to the minimum, and at the same time can potentially reduce chemical control use. The objective of this research was to evaluate the effectiveness of chilling aeration to preserve grain quality and control insect-pests. The research trial was developed from August to November 2015 in Central Kansas in two 1,270 metric tons (MT) steel bins with low-moisture wheat from the 2015 summer harvest. One bin was chilled and the other was used as a control (ambient aeration). Variables evaluated were: moisture content (MC), grain and flour quality, insectpest development and reproduction rate, insect fragments per kg, and fungi presence. Chilling aeration cooled the grain in 135 hours to an average of 17⁰C, with minimum variation through the four months. Ambient aeration in the control bin cooled the grain to an average of 22⁰C after 308 hours, with variation over 16⁰C through the four months. Lower temperatures significantly diminished insect development and reproduction rate. Flour quality was better preserved in the chilled than in the control bin. There was no significant effect on MC, grain quality or fungi presence. The energy cost of running the grain chiller was 0.22 $/MT more than the cost of ambient aeration in the control bin. KeywordsAmbient aeration, chilling aeration, end-product quality, fungi, grain temperature, grain quality, insect-pests