The most influential factors in the storage of grains is moisture and temperature. According to Utah State University grains containing less than 12% moisture and pulses (legumes harvested solely for the dry seed) with less than 10% moisture can be stored for food purposes indefinitely.
Grains as defined by the University include barley, corn, millet, oats, rice, rye, sorghum, triticale and wheat. Pulses include beans, broadbeans (fava beans), chickpeas, lentils and dried peas.
High moisture content in grain of over 12% causes damage to the seeds because it promotes diseases. At 13 ½ to 15% moisture levels some fungal spores begin to grow, other species of fungi require 16 – 23%. Aerobic bacteria require 20% to grow. Grains stored with these moisture levels will spoil and become unfit for food and can spontaneously ignite under ideal conditions.
The moisture content of grains can be determined at home. Take 20 ounces of grain from the middle of the bag or bin and place it in a large baking dish. The grain cannot exceed one inch in depth. Heat the grain in your oven at 180 degrees for 2 hours, stirring occasionally. Allow the grain to cool. Reweigh the grain, a one ounce loss of weight shows that it contains approximately 5% moisture. Two ounces = 10% Three ounces = 15%. And so on.
The best temperature for storage is between 40 – 60 degrees. Higher temperature will affect the ability of the stored seeds to germinate over time, but food value is only slightly reduced. Freezing temperatures will not damage stored grains or pulses.
The above information is from a report prepared by Ralph E Whitesides, Extension Agronomist at the Utah State University Cooperative Extension.