Nuclear magnetic resonance freezing sensor

• US 5,602,477 A
• Filed: 02/06/1995
• Issued: 02/11/1997
• Est. Priority Date: 02/06/1995
• Status: Expired due to Fees

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: McCarthy, Michael J., Reid, David S.
• Primary Examiner(s): Arana, Louis M.
• Application Number:
  US08/384,568
• Time in Patent Office: 736 Days
• Field of Search: 324/300, 324/306, 324/308, 324/312, 324/315, 324/307, 324/309
• US Class Current: 324/315
• CPC Class Codes: G01N 24/085 Analysis of materials for the purpose of controlling industrial production systems
• CPC Class Codes: G01R 33/44 using nuclear magnetic resonance [NMR] G01R33/24, G01R33/62 take precedence

Abstract

A non-invasive apparatus and method for determining changes in the enthalpy of an object undergoing a freezing cycle using nuclear magnetic resonance (NMR) imaging (NMRI) techniques. Enthalpy is determined from the position of the ice interface of said object or, alternatively, from the liquid/solid ratio of the object.

Claims

1. A nuclear magnetic resonance freezing sensor, comprising:

(a) means for subjecting an object containing fluid to nuclear magnetic resonance imaging and acquiring images of said object;

(b) means for identifying the ice content in said object while said fluid freezes from said images; and

(c) means for determining a change in enthalpy of said object from the ice content.

2. An apparatus for monitoring freezing of foods, comprising:

(a) means for subjecting an object containing water to nuclear magnetic resonance imaging and acquiring images of said object;

(b) means for identifying the position of the ice interface in said object from said images as sufficient heat is removed from said object for said water to freeze; and

(c) means for determining a change in enthalpy of said object from the position of the ice interface.

3. An apparatus for measuring changes in enthalpy during controlled freezing of food, comprising:

(a) means for subjecting an object containing fluid to nuclear magnetic resonance imaging and acquiring images of said object;

(b) means for determining the position of a transition for high to low signal intensity in said images as said fluid freezes; and

(c) means for determining a change in enthalpy of said object from said intensity transition.

4. An apparatus for sensing the changes in enthalpy during transition from a liquid to solid state during controlling freezing of food, comprising:

(a) means for subjecting an object containing fluid to nuclear magnetic resonance imaging;

(b) means for acquiring images of liquid portions of said object from said nuclear magnetic resonance imaging;

(c) means for acquiring images of solid portions of said object from said nuclear magnetic resonance imaging;

(d) means for determining the liquid/solid ratio of said object from said images;

(e) means for determining a change in enthalpy of said object from said liquid/solid ratio.

5. An apparatus for sensing the changes in enthalpy during transition from a liquid to solid state during controlling freezing of food, comprising:

(a) means for subjecting an object containing fluid to nuclear magnetic resonance signals;

(b) means for determining the liquid/solid ratio of said object from said signals during freezing of said object; and

(c) means for determining a change in enthalpy of said object from said liquid/solid ratio.

6. A method of sensing freezing of an object, comprising:

(a) subjecting an object containing fluid to nuclear magnetic resonance imaging and acquiring images of said object;

(b) identifying the ice content in said object from said images while said fluid freezes; and

(c) determining a change in enthalpy of said object from the ice content.

7. A method of sensing freezing of foods, comprising:

(a) subjecting an object containing water to nuclear magnetic resonance imaging and acquiring images of said object;

(b) identifying the position of the ice interface in said object from said images as sufficient heat is removed from said object for said water to freeze; and

(c) determining a change in enthalpy of said object from the position of the ice interface.

8. A method of measuring changes in enthalpy during controlled freezing of food, comprising:

(a) subjecting an object containing fluid to nuclear magnetic resonance imaging and acquiring images of said object;

(b) determining the position of a transition for high to low signal intensity in said images as said fluid freezes; and

(c) determining a change in enthalpy of said object from said intensity transition.

9. A method of sensing the changes in enthalpy during transition from a liquid to solid state during controlling freezing of food, comprising:

(a) subjecting an object containing fluid to nuclear magnetic resonance imaging;

(b) acquiring images of liquid portions of said object from said nuclear magnetic resonance imaging;

(c) acquiring images of solid portions of said object from said nuclear magnetic resonance imaging;

(d) determining the liquid/solid ratio of said object from said images during freezing of said object;

(e) determining a change in enthalpy of said object from said liquid/solid ratio.

10. A method of sensing the changes in enthalpy during transition from a liquid to solid state during controlling freezing of food, comprising:

(a) subjecting an object containing fluid to nuclear magnetic resonance signals;

(b) determining the liquid/solid ratio of said object from said signals during freezing of said object; and

(c) determining a change in enthalpy of said object from said liquid/solid ratio.