THE SPONTANEOUS HEATING OF FLAXSEED AND SUNFLOWER SEED STORED UNDER ADIABATIC CONDITIONS

Abstract

The effects of moisture content on the heating of flaxseed and sunflower seed were studied in an adiabatic thermostat. Under these conditions, storage periods of less than two months produced heating in flax at 11.4% moisture and in sunflower seed at 10.5% moisture. Thus it appears that the commercial limits of 10.5 and 9.5%, moisture respectively are not too low for these grains.Evidence is presented to show that an acceleration in the over-all respiration rate of flaxseed and sunflower seed precedes heating. This indicates that heating is caused by active growth of the microflora on the grain and, at moisture levels in the order of those required for safe storage, normal embryonic activity is insufficient to cause heating.It is suggested that when the relative humidity of the interstitial air in bulk grain exceeds a value of 74% the microflora will grow and heating may ensue. From this it follows that the moisture content of any grain, in equilibrium with air at a relative humidity of 74%, will closely approximate the upper limit permissible for admission to 'straight' grades.