Literally there are many many ways to test for moisture content, with each
one giving a different number. They can be categorized into;
1. air drying methods
2. air dry assisted with microwave
3. infrared drying
4. vacuum oven methods
5. freeze drying
6. drying over a desiccant (eg phosphorus pentoxide)
All the above are characterized by a time-temperature regime eg 16 hr at
160°F
Other methods include:
7. azeotropic solvent extraction/distillation eg toluene
8. calcium carbide reaction with water (used for high moisture slurries
like cement or ground rat carcasses in nutritional studies)
9. culombic titration with an indicator :Karl Fischer²
The later is the gold standard I have copied Dr Hans Deiter Isengard as
he is the guru for standards)
10. Instrumental spectroscopy with a standard intensity vs moisture prepared
by one of the above
10. NIR
11. microwave absorption
12. nuclear magnetic resonance or decay (FID)
>From an industry commercial standpoint knowledge of moisture content is
important to ensure one is paying for solids not added water. Thus in the
grain business price is adjusted to a 14% moisture basis. I presume your
industry has some such standard so that added water is detected and price
adjusted. Given that you can use any of the above as long as you have a
calibration curve that translates your moisture into a value that is done
for the standard. This way you can choose a faster method and get the
corrected number on the standard basis. I assume that is what is in the
USDC¹s manual and supplements.
Dr. Ted Labuza Morse Alumni Distinguished Professor of Food Science and
Engineering
Dept. of Food Science & Nutrition 136 ABLMS U of Minn St Paul, MN 55108
Voice 612-624-9701 Fax 612-625-5272 home fax 651-483-3302
cell 651-307-2985 email tplabuza@umn.edu
PDA Text message 6513072985@mobile.mycingular.com
home page http://www.ardilla.umn.edu/Ted_Labuza/
Louis Pasteur (12/7/1854): "In the fields of observation, chance favors only
the prepared mind. There does not exist a category of science to which one
can give the name applied science. There are science and the applications of
science, bound together as the fruit of the tree which bears it."
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