The effects of Temperature and Moisture on Stored Grains

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.

20 ounces of grain in pan

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.

dried wheat on scale

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.

Howard

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5 Responses to The effects of Temperature and Moisture on Stored Grains

  1. Angie says:

    I am new to food storage and preparation. I have put dried milk, beans, rice and oats in the freezer. Can I take them out and put them in Mylar bags to make space in freezer for meat? My concern is when removed there will be moisture from condensation. I want to do it correctly and not lose any of my food.

    • Noah says:

      How airtight were the containers when they went in the freezer? A sealed mylar bag, a canning jar — those would keep food safe from moisture, but if you have any questions, you could put the food on metal baking sheets and dry them in the oven set at the lowest temperature for a few minutes. You could also add a desiccant to the mylar bags you’re planning to use for storage along with an oxygen absorber. Personally, if I wasn’t 100% sure the food remained dry in the freezer, I would put it in the oven for just a few minutes OR in a dehydrator to make sure all moisture was removed.

  2. Angie says:

    Thank you so much! The powdered milk I put in gallon freezer bags and tried to remove all air out as much as possible.

  3. GJ says:

    When you mention “degrees”, you mean Fahrenheit as opposed to Celcius?
    Since the rest of the article use non-metric units, I assume this to be the case.
    might be goog to add to this (and other) articles since it’s read by international visitor 😉
    Heating the grains to 180C (356F) is probably not a good idea…

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