Checklist for drying and storage.
August 12, 2004
Store beans at 18% moisture during the fall and winter -- if cooled to less than 50 degrees F in October and 30 degrees in November. Lower moisture contents should be used if longer storage periods are desired or the beans cannot be cooled to the specified temperatures. If the beans can be kept cooler, the acceptable moisture content can be increased. If the beans can be kept at 60 degrees F or cooler, the moisture content can be 14% for long term storage.
Take extra care when using a high temperature dryer. The relative humidity of the drying air should not be lower than about 30% when drying Navy beans. Normally the drying should occur with the air heated less than about 20 degrees above the outdoor air temperature to keep the relative humidity above 30%. The beans need to be monitored continuously to assure that they are not being damaged. Other beans are best dried with no supplemental heat.
Give natural air drying a chance. Natural air drying will work well for drying edible beans during mid-September to mid-October in North Dakota. Based on average climatic conditions, beans should dry to about 14% moisture. Shutting fans off during the warmest part of the day will raise the final moisture content but lengthen the drying time. Shutting fans off during periods of higher humidity, such as night, will reduce the final bean moisture content.
Move beans gently. Belt conveyors are preferred due to their gentleness in conveying. Drop heights must be limited. A bean ladder should be used inside storage bins to reduce impact damage. The speed of auger rotation should be reduced and augers operated full to minimize damage. Elevator legs need to be adapted for handling beans, including reducing the discharge velocity and utilizing a method of gently slowing the beans at the bottom of spouts.
Check stored beans regularly. It is important to measure the temperature and moisture content of the beans at least monthly. Whenever there is more than a 10 degree differential between the average outdoor temperature and the bean temperature during the fall, the beans should be cooled with aeration. This should continue until beans at 16% moisture are cooled at least to 40 degrees F and 18% moisture beans are cooled to about 30 degrees F. Cooling below 30 degrees F is not necessary and may increase the potential for handling damage.
-- Source: NDSU Extension Service.