Cooling bulk grain in the British climate to control storage insects and to improve keeping quality

Abstract

AbstractA study of the properties of bulk grain, the heat production of insects and their rates of breeding shows that the cooling of grain in bulk by aeration should control granivorous insects. The grain temperature needs to be lowered to 17–22°, depending on the species of insect. Deterioration of the grain, particularly of its viability, must be avoided, before, during and after cooling by aeration; safe combinations are given for grain moisture content, storage temperature and storage time. Laboratory‐scale aeration experiments indicate that barley will not absorb moisture unduly if aerated with untreated air when the atmospheric relative humidity does not exceed 75% in autumn or 80% in winter.An example of the successful cooling of large bulks of malting barley by aeration with fans in commercial stores is described. Aeration for 56–94 h. at the rate of 0.16 cu. ft./m. of air per bushel of grain, in one to three stages, cooled 240,000 bushels (6000 tons) of malting barley in five fairly shallow stores within 3 months of the start of loading. Grain was cooled most quickly along the shortest distances between the aeration duct and the surface of a bulk.On the basis of a review of weather information for 12 years the British Isles were divided into three regions, good, satisfactory and doubtful for aeration. The barley stores described were in the good region. Design of aeration systems for British weather conditions is discussed, including automatic control of aeration.It is concluded that in British conditions cooling by in‐store aeration is a reliable, labour‐saving, economic method of avoiding the trouble caused by granivorous insects in stores of cereal grains. It should also enable some economies in the amount of drying or of cooling in dryers to be made. Of the cooling methods considered, in‐store aeration is the most economical method of cooling the grain.