Electronic moisture tester

• US 20060188616A1
• Filed: 02/24/2005
• Published: 08/24/2006
• Est. Priority Date: 02/24/2005
• Status: Active Grant

• Current Assignee: Sunsweet Growers, Inc.
• Original Assignee: Sunsweet Growers, Inc.
• Inventors: Davies, Orion, Pierce, Brian N., Gildemeister, Michael
• Granted Patent: US 7,609,074 B2
• Time in Patent Office: Days
• US Class Current: 426/231
• CPC Class Codes: G01N 27/048 for determining moisture content of the material
• CPC Class Codes: G01N 33/025 Fruits or vegetables

Abstract

The moisture content of a foodstuff or other solid matter is determined by reducing the matter to a paste, packing the paste into a vessel equipped with multiple pairs of plate electrodes and one or more temperature sensors, applying an AC voltage across each pair of electrodes, and measuring the impedance of the paste from each pair of electrodes. The multiple impedance measurements are averaged or otherwise processed to obtain a value that is representative of the paste, and that value and the temperature are processed against calibration data to achieve a value of the moisture content of the paste.

Claims

1. A process for determining moisture content in solid matter, said process comprising:

(a) reducing said solid matter to a paste;

(b) placing said paste in an elongated vessel having a longitudinal axis, said vessel containing pairs of electrodes positioned at a plurality of locations along said axis;

(c) imposing an alternating voltage at a selected frequency across each of said pairs of electrodes and through said paste, determining an electrical impedance value across each of said pairs arising from said alternating voltage, and generating a signal representative of each of said values;

(d) detecting the temperature of said paste in said tube; and

(e) compiling test data from said signals and said temperature, and comparing said test data so compiled to calibration values correlating said test data with moisture levels, thereby determining said moisture content of said solid matter.

2. The process of claim 3 wherein the electrodes of any single pair are separated by a gap, and the gaps of all said pairs are of equal width.

3. The process of claim 1 wherein said elongated vessel contains from 5 to 100 pairs of electrodes, the electrodes of any single pair directly opposing each other across said axis.

4. The process of claim 1 wherein said elongated vessel contains from 10 to 60 pairs of electrodes, the electrodes of any single pair directly opposing each other across said axis.

5. The process of claim 1 wherein said alternating voltage has a maximum voltage ranging from about 1 mV to about 100 V.

6. The process of claim 1 wherein said alternating voltage has a maximum voltage ranging from about 0.1 V to about 50 V.

7. The process of claim 1 wherein said alternating voltage has a maximum voltage ranging from about 0.3 V to about 30 V.

8. The process of claim 1 wherein said selected frequency is from about 60 Hz to about 200 kHz.

9. The process of claim 1 wherein said selected frequency is from about 300 Hz to about 30 kHz.

10. The process of claim 1 wherein step (a) comprises forcing said solid matter through a perforated plate.

11. The process of claim 1 wherein step (b) comprise placing from about 3 to about 3,000 cm³ of said paste in said elongated vessel.

12. The process of claim 1 wherein step (b) comprise placing from about 10 to about 1,000 cm³ of said paste in said elongated vessel.

13. The process of claim 1 wherein step (d) is performed by at least one thermistor within said vessel.

14. The process of claim 1 wherein step (d) is performed by a plurality of thermistors within said vessel.

15. The process of claim 1 wherein step (e) comprises averaging a plurality of said signals to yield an average signal value and comparing said average signal value and said temperature to an algorithm representing a three-dimensional curve.

16. Apparatus for determining moisture content in solid matter, said apparatus comprising:

an elongated vessel having a longitudinal axis and containing pairs of electrodes positioned at a plurality of locations along said axis;

means for imposing an alternating voltage across each of said pairs of electrodes and for detecting electrical impedance across each of said pairs; and

means for detecting the temperature of the interior of said vessel.

17. The apparatus of claim 16 wherein said elongated vessel is of uniform cross section and the electrodes of any single pair are separated by a gap, the gaps of all said pairs being of equal width.

18. The apparatus of claim 16 comprising from 5 to 100 pairs of said electrodes, the electrodes of any single pair directly opposing each other across said axis.

19. The apparatus of claim 16 wherein comprising from 10 to 60 pairs of electrodes, the electrodes of any single pair directly opposing each other across said axis.

20. The apparatus of claim 16 wherein said means for detecting the temperature of the interior of said vessel are comprised of at least one thermistor.

21. The apparatus of claim 16 wherein said means for detecting the temperature of the interior of said vessel are comprised of a plurality of thermistors.

22. The apparatus of claim 16 further comprising means for reducing solid matter to a paste.

23. The apparatus of claim 22 wherein said means for reducing solid matter to a paste is a drive means arranged to force said solid matter through a perforated plate.

24. The apparatus of claim 16 in which said elongated vessel has an internal capacity of from about 3 to about 3,000 cm³.

25. The apparatus of claim 16 in which said elongated vessel has an internal capacity of from about 10 to about 1,000 cm³.