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United States Department of Agriculture

Agricultural Research Service

Research Project: Quality Based Inspection and Sorting of Specialty Crops Using Imaging and Physical Methods

Location: Healthy Processed Foods Research

Title: Modernization of the DFA Moisture Meter

Authors
item Haff, Ronald
item Young, Richard

Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 1, 2012
Publication Date: April 1, 2012
Citation: Haff, R.P., Young, R. 2012. Modernization of the DFA Moisture Meter. Applied Engineering in Agriculture. 28(2):221-223.

Interpretive Summary: The Dried Fruit Association (DFA) Dried Fruit Moisture Tester has been the standard technique for determining moisture in dried fruit for more than 50 years. This method of testing moisture is recognized world wide and is AOAC approved. The meter applies the results of conductivity measurements and temperature to lookup tables developed by DFA to determine moisture content. The validity of the lookup tables is highly dependant on the repeatability of the conductivity measurements, and thus on the reproducibility of the somewhat archaic analog components of the meter itself, which is unchanged for over fifty years. Furthermore, the availability of these parts has become problematic in recent years. Here we report a redesign of the meter using modern electrical components that exactly mimic the workings of the original parts, and therefore would not compromise the AOAC accreditation for the instrument. The redesigned instrument was tested using raisins and dried prunes at various temperatures, comparing results to those obtained with the original design for the same samples. Results for the new meter were not significantly different from those of the original design with a 99 percent level of significance.

Technical Abstract: The Dried Fruit Association (DFA) Dried Fruit Moisture Tester has been the standard technique for determining moisture in dried fruit for more than 50 years. This method of testing moisture is recognized world wide and is AOAC approved. The meter applies the results of conductivity measurements and temperature to lookup tables developed by DFA to determine moisture content. The validity of the lookup tables is highly dependant on the repeatability of the conductivity measurements, and thus on the reproducibility of the somewhat archaic analog components of the meter itself, which is unchanged for over fifty years. Furthermore, the availability of these parts has become problematic in recent years. Here we report a redesign of the meter using modern electrical components that exactly mimic the workings of the original parts, and therefore would not compromise the AOAC accreditation for the instrument. The redesigned instrument was tested using raisins and dried prunes at various temperatures, comparing results to those obtained with the original design for the same samples. Results for the new meter were not significantly different from those of the original design with a 99 percent level of significance.

Last Modified: 11/26/2014
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