System and technique for ultrasonic determination of degree of cooking

• US 20040195231A1
• Filed: 04/03/2003
• Published: 10/07/2004
• Est. Priority Date: 04/03/2003
• Status: Active Grant

• Current Assignee: Battelle Memorial Institute
• Original Assignee: Battelle Memorial Institute
• Inventors: Pappas, Richard A., Morgen, Gerald P., Judd, Kayte M., Pfund, David M., Cliff, William C., Diaz, Aaron A., Bond, Leonard J.
• Granted Patent: US 7,191,698 B2
• Time in Patent Office: Days
• US Class Current: 219/400
• CPC Class Codes: F24C 7/08 Arrangement or mounting of control or safety devices
• CPC Class Codes: H05B 6/687 for cooking

Abstract

A method and apparatus are described for determining the doneness of food during a cooking process. Ultrasonic signal are passed through the food during cooking. The change in transmission characteristics of the ultrasonic signal during the cooking process is measured to determine the point at which the food has been cooked to the proper level. In one aspect, a heated fluid cooks the food, and the transmission characteristics along a fluid-only ultrasonic path provides a reference for comparison with the transmission characteristics for a food-fluid ultrasonic path.

Claims

1. An apparatus for monitoring the degree of doneness of food comprising:

a vessel;

a fluid contained in said vessel;

a quantity of food disposed in said fluid;

means for heating said fluid to cook said food;

first and second ultrasonic transducers acoustically associated with said vessel wherein ultrasonic signals transmitted by said first ultrasonic transducer are received by said second ultrasonic transducer and pass through at least a portion of said fluid and said food; and

a processing device operable to receive the output from said second ultrasonic transducer representative of said signal received by said second ultrasonic transducer, wherein said output exhibits at least one transmission characteristic of said received signal which varies as a function of the doneness of said food;

wherein the processing device is further operable to determine a first value corresponding to the doneness of said food from the received output and a value corresponding to an ultrasonic characteristic of the fluid.

2. The apparatus described in claim 1, wherein said fluid includes water.

3. The apparatus described in claim 1, wherein said fluid includes cooking oil.

4. The apparatus described in claim 1, wherein said fluid includes steam.

5. The apparatus described in claim 1, wherein said transmission characteristic is the acoustic velocity of said ultrasonic signal.

6. The apparatus described in claim 1, wherein said transmission characteristic is the attenuation of said ultrasonic signal.

7. The apparatus described in claim 1, wherein said processing device is operable to receive a signal representing ultrasonic signals which pass through said fluid along an acoustic path substantially devoid of said food for forming a reference signal representative of the ultrasonic characteristic of the fluid.

8. The apparatus described in claim 7, wherein said reference signal is received by one of said first or second transducers.

9. The apparatus described in claim 1, wherein said vessel is movable such that for at least a period of time said ultrasonic signal passes through said fluid along an acoustic path substantially devoid of said food.

10. The apparatus of claim 1 wherein said transducers are selectively operable to transmit and receive ultrasound through at least a portion of said food at a plurality of different ultrasonic frequencies.

39. The apparatus of claim 1 wherein ka is less than about 2, where a is a characteristic dimension of the food and k is the wavenumber of the ultrasound received by the second transducer defined as 2π

/λ

.

40. The apparatus of claim 7 wherein ka is less than about 5, where a is a characteristic dimension of the food and k is the wavenumber of the ultrasound received by the second transducer defined as 2π

/λ

.

41. The apparatus of claim 40 wherein at least one the first and second transducers has a characteristic dimension D and D/a is greater than about 2.

11. A method for determining the doneness of food comprising:

providing a quantity of food to be cooked;

while cooking said food through contact with a heated fluid, transmitting an ultrasonic signal through said food and said fluid;

receiving said ultrasonic signal;

processing said received signal to extract a characteristic of said received signal,

processing said characteristic with a value corresponding to an acoustic property of said fluid to define a value that changes in relation to the doneness of said food.

12. The method described in claim 11, wherein said characteristic is the acoustic velocity of said ultrasonic signal.

13. The method described in claim 11, wherein said characteristic is the attenuation of said ultrasonic signal.

14. The method described in claim 11, further comprising transmitting an ultrasonic reference signal through said heated fluid along an acoustic path substantially devoid of food and receiving said reference signal and determining the value corresponding to an acoustic property of said fluid from said reference signal.

15. The method described in claim 14, wherein said received signal is compared with said reference signal.

16. The method described in claim 15, wherein cooking includes blanching.

17. An apparatus for monitoring the degree of doneness of food comprising:

a quantity of food to be cooked;

means for heating said food to a temperature sufficient to cook said food;

first and second opposed ultrasonic transducers acoustically associated with said food wherein ultrasonic signals transmitted by said first ultrasonic transducer are received by said second ultrasonic transducer and pass through at least a portion of said food; and

a processing device operable to receive an output from said second ultrasonic transducer representative of said signal received by said second ultrasonic transducer, wherein said output exhibits at least one transmission characteristic of said received signal which varies as a function of the doneness of said food.

wherein the processing device is further operable to determine a first value corresponding to the doneness of said food from the received output and a value corresponding to an ultrasonic characteristic of the fluid.

18. The apparatus described in claim 17, wherein said food includes vegetables.

19. The apparatus described in claim 17, wherein said food includes potatoes.

20. The apparatus described in claim 17, wherein said food includes rice.

21. The apparatus described in claim 17, wherein said food includes grain.

22. An apparatus for monitoring the degree of doneness of food comprising:

a vessel;

a fluid contained is said vessel;

a quantity of food disposed in said fluid;

means for heating said fluid in said vessel to cook said food;

first and second ultrasonic transducers located adjacent to said vessel and positioned such that a portion of said fluid substantially without food lies between said first and second transducers;

third and fourth ultrasonic transducers located adjacent to said vessel and positioned such that a portion of said food lies between said third and fourth transducers; and

a processing device operable to receive an output from said second ultrasonic transducer representative of the transmission characteristics through said fluid and to receive an output from said fourth ultrasonic transducer representative of the transmission characteristic through said fluid and said food, said processing device being operable to process said output signals from said second and said fourth transducers to obtain a signal which exhibits at least one transmission characteristic of said food and not said fluid.

23. A method for determining the doneness of food comprising:

providing a container holding a quantity of heated fluid and a quantity of food to be cooked by said heated fluid;

transmitting an ultrasonic signal through said food wherein said ultrasonic signal is of substantial length and includes at least one of frequency modulation and amplitude modulation;

receiving said ultrasonic signal;

cross correlating said received ultrasonic signal with said transmitted ultrasonic signal to extract a value representing the acoustic group velocity of the transmitted signal;

processing said received signal to extract a characteristic of said received signal, said characteristic defining a function that changes in relation to the doneness of said food.

24. The method of claim 23 further comprising transmitting a reference ultrasonic signal through said fluid along an acoustic path substantially devoid of said food and receiving said reference signal.

25. The method of claim 24 wherein processing includes processing said received signal with said received reference signal to account for variations in said fluid.

26. The method of claim 23 wherein ultrasound is transmitted at a plurality of different frequencies through said food.

27. A method for determining the doneness of food comprising:

providing a container for holding a quantity of fluid;

immersing a quantity of food to be cooked within said fluid in said container;

heating said fluid to a temperature sufficient to cook said food;

transmitting an ultrasonic signal through said fluid along an acoustic path substantially devoid of food;

transmitting an ultrasonic signal through said fluid and said food;

receiving said ultrasonic signals;

processing said received ultrasonic signals to extract a characteristic defining a function that changes in relation to the doneness of said food.

28. The method of claim 27 wherein ultrasound is transmitted at a plurality of different frequencies through said food.

29. The method of claim 27 wherein said fluid is heated prior to immersing said food in said fluid.

30. The method of claim 27 wherein said fluid is flowing relative to said food.

31. The method of claim 27 wherein processing said received ultrasonic signals includes cross-correlating said transmitted signals with said received signals to determine a value corresponding to ultrasonic group velocity.

32. A method of cooking comprising:

immersing food to be cooked in a heated fluid;

transmitting an ultrasonic signal through said food while it is being cooked by said heated fluid;

receiving said ultrasonic signal;

processing said received ultrasonic signal to extract a characteristic defining a function that changes in relation to the doneness of said food;

removing said food from said heated fluid when a predetermined degree of doneness is achieved as indicated by said extracted characteristic.

33. The method of claim 32 further comprising transmitting and receiving an ultrasonic reference signal through said fluid along an acoustic path substantially devoid of food.

34. The method of claim 33 wherein processing said received ultrasonic signal includes processing said received ultrasonic signal with said received ultrasonic reference signal.

35. The method of claim 34 wherein the heated fluid is a liquid.

36. The method of claim 34 wherein at least one the transmitting or receiving is with a transducer that has a characteristic dimension D and wherein the food has a characteristic dimension a and D/a is greater than about 2.

37. The method of claim 34 wherein ka is less than about 5, where a is a characteristic dimension of the food and k is the wavenumber of the transmitted ultrasonic signal defined as 2π

/λ

.

38. The method of claim 34 further comprising obtaining ultrasonic backscattering data.