This method is for measuring moisture content in whole grains and legumes. Grain flours or meals, milk powders and any other finely textured foods should use Method Three detailed below.
To be done prior to measuring -- choose a shallow heat resistant container that has a close fitting lid. Clean it thoroughly and dry completely in your oven for 10-15 minutes. Allow it to cool and then weigh it carefully. This will give you the tare weight or what your container weighs empty.
Depending on how your scale is calibrated you can use a smaller sample size than what is indicated below. Using the twenty-ounce sample mentioned in the following text will allow for fairly accurate readings with the average postal scale. A scale that will measure to the gram could use as small a sample as 20 grams. A powder scale could use even less, but the smaller your sample size becomes the more finicky care you must exercise not to allow error to creep in. Keep your sample size large enough to easily work with.
Allowing for the weight of the sample pan, measure out a weighed twenty-ounce representative sample of the grain or legumes in question. Ideally, you should thoroughly mix the entire lot immediately before removing the sample, but if this is not possible then take it from the middle center of the container. It is important that you use care in this measurement since it will affect all following determinations.
Put the sample in the container making sure it is not more than an inch deep. Place it in the oven with the lid off and allow to heat. Below is a table giving the oven temperatures and times per grain or legume type:
Time and Temperature
Settings for Determining Moisture Contents of Whole Seeds
Seed | Oven Temperature ° Fahrenheit* | Oven Temperature ° Celsius* | Oven Heating Time |
---|---|---|---|
Barley | 266 | 130 | 20 |
Beans | 217 | 103 | 72 |
Corn | 217 | 103 | 72 |
Oats | 266 | 130 | 22 |
Rye | 266 | 130 | 16 |
Sorghum, millet | 266 | 130 | 18 |
Soybeans, peanuts | 217 | 103 | 72 |
Wheat, rice | 266 | 130 | 19 |
*No home oven that I am aware of will allow for such precise temperature control. Try to keep the temperature within ten degrees either way of what is listed and you will still achieve useful results. |
When the dehydration period is over place the close fitting lid on the sample pan and allow to cool in the oven with the door closed. Remove and carefully weigh the pan.
A one ounce loss in weight indicates your grain has a roughly five percent moisture content, 2 ounces indicates that it has a 10% moisture content, etc., etc. You might even be able to cut it as fine as a half-ounce loss, but I wouldn't try to take it further than that.
Obviously, this is only a rough measure, but it works and can be done with postal or dietetic scales that are available virtually everywhere. As I mentioned above, if you have a scale with a finer calibration it is possible to use a smaller sample size and achieve the same result.
METHOD THREE
This method is much faster to use than the first, but greater care must be taken to prevent error. It can be used to determine moisture contents of whole grains and legumes, flours, meals and various food powders.
The same equipment as was used in Method Two will be required here as well as a low-RPM grain mill or some other device that can reduce a quantity of the grain to a meal consistency with only minimal heating of the sample. If the food to be tested is already at a meal consistency or finer then it can be used as-is.
Grind a quantity of product from which you want to measure the moisture content. Take care to grind the sample slowly enough to keep friction heat build up to a minimum (should not be more than mildly warm) or else moisture will be lost due to heat evaporation before it can be weighed.
Immediately upon finishing the grinding, weigh out your sample so as to minimize unmeasured moisture loss.
Place the sample in the oven and dehydrate in the manner used in Method Two for a period of two hours at a temperature setting of 275° F (135° C). When the heating period is finished cover with the tight-fitting lid and allow to cool in the oven. Remove and weigh carefully. Moisture determination is the same as above.
If anyone has a better way of measuring moisture levels which can be done without a lab or special equipment I'd surely like to hear from you.
A.3.2 CLEANING IT YOURSELF
If you've chosen to purchase field-run grain or if the pre-cleaned product you've bought isn't clean enough to suit you it can be given further cleaning.
The fastest and easiest method is "fanning", a form of winnowing. This is done by pouring the grain slowly through the air stream of a fan or blower into a clean, deep container such as a cardboard box or trash can. The wind blowing through the falling grain will blow out most of the broken kernels, chaff, smut balls, mouse droppings, etc. If you're losing too much good grain, try turning the fan down or moving it further back from the container. The deep container will cut down on the amount of kernels that bounce out. Repeat fanning as necessary until the grain is clean enough to suit or you've blown all of the lighter contaminants out.
If the fanning didn't get the grain clean enough it can be further cleaned by running it through a screen or sieve. This should be made with holes just big enough to pass an average sized grain of what it is you're cleaning. Obviously, the size of the holes will necessarily vary depending upon the kernel size of the grain.
Should the kernels still not be clean enough to suit then you'll just have to resort to hand picking out the offending particles. I'd strongly suggest doing this just prior to grinding where it can be done in small batches rather than trying to do your entire storage all at once. It's much easier to do a few pounds at a time than fifty or a hundred.
If you have it in mind to wash the grain, this should not be done prior to storage, but rather just before use. After rinsing, dry the grain immediately in an oven heated to 150° F (117 ° C) for an hour in a layer no deeper than 1/2 inch deep stirring often.
Updated: 9/18/96; 4/16/97; 7/21/97; 10/20/97; 9/15/98; 11/02/99; 12/01/03
Copyright © 1996, 1997, 1998, 1999, 2003. Alan T. Hagan. All rights reserved.
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