WO2008004898A2

WO2008004898A2 - Electrical stimulation of carcasses

Info

Publication number: WO2008004898A2
Application number: PCT/NZ2007/000170
Authority: WO
Inventors: Clyde Charles Daly; Chris Mudford
Original assignee: Meat & Wool New Zealand Limited; Meat & Livestock Australia Limited
Priority date: 2006-07-05
Filing date: 2007-07-05
Publication date: 2008-01-10
Also published as: WO2008004898A3

Abstract

The invention in one aspect provides a method of determining the pH of a carcass or part thereof. The method comprises stimulating the carcass with an electrical test signal; measuring the response of the carcass to the test signal; deriving a set of response data values obtained from measuring the response of the carcass; and determining the pH of at least part of the carcass from the set of response values. The invention further provides a method of reducing the pH of a carcass or part thereof. The method comprises determining the pH of the carcass; comparing the determined pH with a stored target pH value; stimulating the carcass with an electrical corrective signal if the determined pH is greater than the stored target pH value; and repeating the foregoing steps until the determined pH is less than the stored target pH value. The invention also provides related systems.

Description

ELECTRICAL STIMULATION OF CARCASSES

FIELD OF THE INVENTION

The present invention relates to electrical stimulation of carcasses and in particular, but not limited to, electrical stimulation of carcasses after slaughter to derive information relating to the pH of one or more key muscles in the carcass.

BACKGROUND TO THE INVENTION

The muscles of a live animal generate energy by breaking down glycogen from supplies in the animal's body. After death, glycogen breakdown continues and lactic acid accumulates. This results in a reduction of the muscle pH, from around 7.0 in the live animal to an ultimate pH of about 5.5 in normal muscle after rigor mortis.

If the animal's muscles cool rapidly before entering rigor, there is typically insufficient time for the stored glycogen to be converted to lactic acid before the muscle becomes cold. Conditions of minimal acidification coincident with cold temperatures causes an irreversible contraction of the muscles. This contraction is referred to as 'cold shortening' and is undesirable because it results in a toughening of the animal's meat.

The traditional preventative measure for cold shortening has been to apply electrical stimulation to the carcass. The stimulation of the carcass' muscles via electrical signals accelerates the breakdown of glycogen after death, minimising the amount of remnant glycogen while raising the amount of lactic acid. In this way, electrical stimulation allows a rapid decline in carcass pH. The rapidity of the pH decline means that the carcass' stored glycogen can be exhausted before the muscle cools, preventing the occurrence of cold shortening.

The application of electrical stimulation also accelerates the rate of tenderisation of carcass meat. This is because the proteolytic events that cause tenderisation start at or near the onset of rigor mortis. Because electrical stimulation accelerates the onset of rigor, it also initiates the tenderisation process earlier while the carcass is warmer, which then results in faster tenderisation. The objective of electrical stimulation in prior art systems is to produce the greatest possible pH decline during electrical stimulation. An example of this is the Accelerated Conditioning and Ageing (AC&A) process developed by the Meat Industry Research Institute of New Zealand (MIRINZ) as a processing specification for exported New Zealand frozen lamb. The intention there was to produce an acceptable level of tenderness before the meat was frozen. As such, a maximal pH decline allowed the opportunity to freeze the meat at the earliest opportunity. Hence, high voltage stimulation based on a 1143 peak voltage was developed.

There are also systems in the prior art where information relating to a carcass is obtained before application of electrical stimulation. In US Patent No. 5,104,352 to Dransfield, the degree to which rigor has developed prior to electrical stimulation is taken into account during electrical stimulation. The development of rigor is evaluated by dropping the carcass along a rail and observing the behaviour of the carcass.

It is an object of the present invention to provide a method, apparatus and system for electrical stimulation of carcasses that either provide improved control over the electrical stimulation process or that at least provide the public with a useful choice.

SUMMARY OF THE INVENTION

In a first aspect, the present invention comprises a method of determining the pH of a carcass or part thereof. The method comprises stimulating the carcass with an electrical test signal, measuring the response of the carcass to the test signal, deriving a set of response data values obtained from measuring the response of the carcass, and determining the pH of at least part of the carcass from the set of response values.

In a second aspect the present invention comprises a method of reducing the pH of a carcass or part thereof. The method comprises:

(a) determining the pH of the carcass by the above method;

(b) comparing the determined pH with a stored target pH value;

(c) stimulating the carcass with an electrical corrective signal if the determined pH is greater than the stored target pH value; (d) repeating steps (a) to (c) until the determined pH is less than the stored target pH value.

In a further aspect the invention comprises a carcass pH determination system comprising an electrical signal generator configured to generate an electrical test signal to stimulate the carcass or part thereof; one or more sensors configured to measure the response of the carcass to the test signal; and a processor configured to receive a set of response data values obtained from the sensor(s) and to determine the pH of at least part of the carcass from the set of response values.

hi a yet further aspect the invention comprises a carcass pH reduction system comprising an electrical signed generator enforced to generate an electrical test signed while in a test mode and to generate an electrical corrective signal while in a corrective mode; one or more sensors configured to measure the response of the carcass to the test signal and to generate a set of response data values; a pH determination component configured to determine the pH of at least part of the carcass from the set of response values; a comparator configured to compare the determined pH with a stored target pH value; and a processor configured to place the signal generator in the corrective mode to generate an electrical corrective signal.

The term 'comprising' as used in this specification means 'consisting at least in part of, that is to say when interpreting statements in this specification which include that term, the features, prefaced by that term in each statement, all need to be present but other features can also be present.

In this specification, where reference has been made to patent specifications, other external documents, or other sources of information, this is generally for the purpose of providing a context for discussing the features of the invention. Unless specifically stated otherwise, reference to such external documents or sources of information is not to be construed as an admission that such documents or sources of information in any jurisdiction are prior art, or form part of the common general knowledge in the art. BRIEF DESCRIPTION OF THE FIGURES

Preferred forms of the method, apparatus and system of the invention will now be described with reference to the accompanying figures in which:

Figure 1 shows a flow chart of one form of the method of the invention;

Figure 2 shows a flow chart of another form of the method of the invention;

Figure 3 shows a schematic of one form of the apparatus of the invention;

Figure 4 shows a schematic of one form of the system of the invention;

Figure 5 shows a preferred form of the first electrical signal;

Figures 6A and 6B show example signals generated and example signals received by the preferred form apparatus of the invention;

Figure 7 shows example load cell responses;

Figure 8 shows frequency components extracted from the response data values of Figure 7; and

Figure 9 shows the results of a regression analysis, comparing calculated with actual muscle pH.

DETAILED DESCRIPTION OF THE PREFERRED FORMS

The Preferred Form Method

One preferred form of the method of the invention will now be described with reference to Figure 1. In the form shown, the method of the invention involves electrical stimulation of a carcass to derive information relating to the pH of the carcass. The method begins at step 100, where the carcass is stimulated using an electrical test signal. The electrical test signal, in one form, comprises one or more predetermined electrical pulses. In another form, the test signal comprises one or more sets of predetermined electrical pulses. Example forms of the test signal will be described later in this specification.

During stimulation, the method proceeds to step 102, where the response of the carcass is measured. In one form, the response of the carcass is the force of muscle contraction during stimulation with the test signal. This allows repeated testing of the carcass while the stimulation process is carried out, which in turn makes it possible to stop the stimulation at the appropriate time. As will be described later, the stimulation may be stopped when the derived pH information substantially matches predefined data.

In another form, step 102 comprises the step of removing the application of the test signal before the carcass' response is measured. Where the test signal is a pulse or a set of pulses, the application of the first electrical signal will automatically be reduced or removed in accordance with the pulse(s). As such, step 102 in such an embodiment need not expressly provide for the removal of the application of the first electrical signal.

Preferably, in the above form, as soon as the application of the test signal is removed, the rate of relaxation of the carcass is measured. As will be known in the art, the application of a suitably strong electrical signal to a carcass causes muscles in the carcass to contract. The removal of the application of such an electric signal allows the muscles to relax. The rate of relaxation, as is the case with contraction, has been found to be related to the development of rigor mortis and the pH of at least certain muscles in the carcass.

In another form, the force of contraction and/or the rate of relaxation of the carcass is measured during application of the test signal. In this form, the measurements are preferably made during one or more intervals between electrical pulses that constitute the test signal.

The measurement of force of contraction and/or rate of relaxation allows the present invention to derive information relating to the pH of at least part of the carcass, as will be described later. In the preferred form, the part of the carcass for which pH information is derived is the longissimus dorsi muscles of the carcass.

The force of contraction and/or rate of relaxation of the carcass muscles can be measured in a multitude of ways. In one form, as will be described with reference to the apparatus of the invention in Figure 3, the contraction and/or rate of relaxation is measured using a load cell. In this form, the carcass is suspended from one or more load cells hung from a rail. As the test signal is applied, the muscles in the carcass contract and relax. The forces associated with contraction and/or rate of relaxation of the carcass' muscles are then measured. By appropriately processing the forces measured, the contraction and/or rate of relaxation may be measured. The contraction and/or rate of relaxation may also be measured using other sensors, such as force sensors, strain sensors, or visual imaging means, such as a charge coupled device (CCD) imaging and processing means.

Once the response of the carcass is measured, the preferred form method derives information relating to the pH of the carcass in step 104. The derivation of information may involve comparing the response measured with information in a database providing details of carcass response and likely pH values or ranges. In the preferred form, the response measured is processed to extract relevant data prior to deriving information relating to the pH of the carcass. For instance, the measured response may be a waveform that is signal-processed using Fast Fourier Transform (FFT) or like processes to extract one or more frequency components. In one example, the extracted frequency component(s) may be compared to frequency components in a database to derive the pH information.

The method illustrated in Figure 1 may be used as part of, or independently of, conventional electrical stimulation processes to improve meat quality. For instance, the method may be implemented between applications of conventional electrical stimulation so that information relating to the pH of the carcass may be derived while electrical stimulation is being performed. Specific example applications of the method will be later described in this specification. Another form of the method of the invention will now be described with reference to Figure 2. In this form, the method not only derives pH information, but also includes steps to reduce the pH of the carcass by electrical stimulation. Steps 200, 202 and 204 are equivalent to steps 100, 102 and 104 of Figure 1.

In step 206, the method of Figure 2 includes an enquiry as to whether the pH information derived in step 204 is acceptable. The acceptability of the pH information is typically based on whether the determined pH meets a stored target pH. The acceptability of the pH information may also be based on whether the derived pH is within a range of acceptable pH values. In one embodiment the determined pH is unacceptable if it is greater than the target pH.

If the pH information derived in step 204 is found to be unacceptable, the method of Figure 2 proceeds to step 208, where the carcass is stimulated with an electrical corrective signal. The corrective signal preferably has a higher signal frequency compared to the test signal. The frequency, voltage and duration of the test signal is preferably selected to have minimal or no effect on the pH of the carcass. The corrective signal may be based on signals used in conventional electrical stimulation to reduce the pH of a carcass.

Once stimulated with the second electrical signal, which may be applied in one or more cycles, the method returns to steps 200, 202 and 204 again to derive pH information. If the determined pH information is acceptable, for example less than or equal to the target pH, then the method ends in step 210. If the pH information derived is still unacceptable, the method repeats from step 208 onwards again.

The Preferred Form Apparatus

Referring to Figure 3, the preferred form apparatus of the invention is shown generally as 300. The apparatus optionally includes an input device 305, which may be one or more buttons, switches, keypads, touch screens or the like. The apparatus also includes an electrical signal generator 310. The electrical signal generator 310 is used to generate electrical signals 315 to stimulate a carcass, and may be a conventional constant voltage or a constant current electrical stimulation device. . A processor 320 is provided to control the generation of signals from the electrical signal generator310. In addition, the processor 320 receives input signals from the input device 305 and signals representing the carcass' response to the electrical signals via Iine325. The signals on line 325 may be signals received from one or more load cells or like sensors that are arranged to measure the response of the carcass.

To use the apparatus 300, an operator will typically first connect the apparatus 300 to one or more sensors (not shown) via one or more lines, such as Iine325. If necessary, the electrical signal generator 310 may be connected to a voltage generation device. The operator may begin using the apparatus 300 by inputting, via input device 305, a desired command. In one form, the desired command is for the apparatus to carry out the method of Figure 2 to bring the pH of a carcass down to a specified target pH. The processor optionally presents to the operator via display 330 further options, if applicable. For instance, the processor may be programmed to display and execute a variety of programs to produce different electrical signals via electrical signal generator310. Examples of such programs include a 'sheep' program to produce electrical signals with a peak voltage, V_sheep, to derive pH information of a sheep carcass, and a 'bovine' program to produce electrical signals with a peak voltage, Vbo_vine, that is higher than V_sheep, to derive pH information of a bovine carcass.

The electrical signals generated and outputted from the apparatus are sent in a test mode in the form of an electrical test signal to the carcass for stimulation. The response of the carcass to the test signal is measured, and signals representing this response are fed back into the apparatus 300 via Iine325. The response signals are then analysed by the processor 320 to derive information relating to the pH of the carcass. Preferably, the information derived are displayed on display 330.

A pH determination component 335 determines the pH of the carcass. A Fast Fourier Transform component 340 extracts frequency components from the set of response values. The processor 320 determines pH from the product of the frequency components and a plurality or set of stored coefficients 345. A regression analysis component 350 is operable to derive the stored coefficients 345 from regression analysis on the frequency components and measured pH values. A comparator 355 compares the determined pH with a stored target pH value. If the determined pH is higher than the target pH value then the processor 320 places the signal generator 310 in a corrective mode to generate an electrical corrective signal.

The Preferred Form System

The system of the present invention will now be described with reference to Figure 4. The system includes an electrical stimulation device 400 to deliver electrical energy to one or more carcasses. In the preferred form, the electrical energy is delivered in pulses.

Four carcasses 402 are shown in Figure 4. The carcasses 402 are suspended from a rail 404, which may be part of a conventional overhead rail that is used to transport carcasses in a facility.

To measure the response of the carcass to electrical stimulation, sensor(s) in the form of one or more load cells 406 are mounted in the rail 404 at points where electrical stimulation will take place. The load cell(s) 406 measures the rate of relaxation of the carcass 402 between pulses of electrical energy, and/or the force generated by the carcass 402 when it contracts in response to each pulse.

Signals representing the rate of relaxation, contraction force, or any other parameters indicative of the carcass' response as measured are sent via lines 408 to the electrical stimulation device 400 for analysis. In the preferred embodiment, the electrical stimulation device 400 includes a computing device to analyse the measured response. Alternatively, the computing device is provided separate to the electrical stimulation device 400. In that form, the signals may be directed to the computing device by the electrical stimulation device 400, or may be directly sent from the load cell(s) to the computing device. For simplicity and ease of reference, only single lines 408 are shown to connect the electrical stimulation device 400 and each of the load cells 406. In practice, two or more lines for each load cell 406 would be typically employed. Test signals and corrective signals are introduced to the carcass by a plurality of electrodes 410 mounted along a rubbing bar 412. The bar is positioned so that the electrode(s) contact each carcass as it is transported along rail 404.

The electrical stimulation device 400, or separate computing device, analyses the signals from the sensors to derive pH information relating to the carcass. In one form, the analysis involves correlating the signals, which are received as waveforms, with pH information provided in a database or lookup table.

Example Signals and Responses

In the preferred form, the first electrical signals are test signals having a range of lower frequency pulses used to 'interrogate' the carcass. For instance, while the carcass is hanging from a load cell, a defined set of electrical pulses called test pulses may be introduced into the carcass at intervals of 10- 15 seconds.

The test pulses are preferably unipolar square waves, between 0.1 and 10 milliseconds duration, with a minimum pulse amplitude of 1 Ampere. Test signals are produced from test pulses with pulse intervals varying between 70 and 250 milliseconds, which allows a sufficient time interval between pulses to allow the relaxation rates of the carcass muscles to be measured, and to generate differentiated contractions in response to each stimulation pulse

Referring to Figure 5, the preferred form test pulses are shown generally as 500. The pulses 500 comprise 1 msec duration and 1 Ampere amplitude. The pulse intervals are increased every third pulse to increase the relaxation time between stimuli. The test signal produced from the test pulses is shown generally as 501.

The test signal 501 is preferably introduced into a normal stimulation waveform that is used to stimulate and reduce the pH of the carcass. Referring to Figures 6A and 6B, the test signal, comprising test pulses TP, are introduced into a normal stimulation waveform, comprising stimulation pulses SP. The figures also show the signals, Si, that are introduced into the carcass and the signals, S_m, that are obtained from the carcass by measuring the response of the carcass. In Figure 6A, the response of the carcass to the test pulses TP is shown as Rl. In one form, the response Rl is treated as a waveform whose frequency components are correlated with pH data. This is done by firstly calculating the frequency components of the response using Fast Fourier Transform. Then, using conventional statistical regression techniques, correlations are established between measured pH values and individual frequency responses. Using this method, the response Rl has been found to represent a pH of around 6.7. In Figure 6B, the response R2 has been found to represent a pH of around 6.3.

Figure 7 shows example load cell responses. The response data values 700 are units of force measured in kilograms. The values comprise a sequence of load cell responses at different time values. As a test signal is applied to the carcass the carcass muscle contracts and pulls up against the overhead rail. This causes the load cell to record an increase in weight as shown for example at 705.

Stopping the test signal results in the muscle relaxing. The carcass goes into partial free fall. This causes the load cell to record a decrease in weight as shown at 710.

Figure 8 shows the frequency components extracted from the response data values of Figure 7.

Figure 9 shows the results of regression by the regression analysis component. The graph shows the relationship between determined or calculated pH values 900 and measured pH values 905.

Example Applications of the Present Invention

The present invention may be used to control the pH-temperature decline of a carcass during processing. The pH-temperature decline is the rate at which carcass pH level falls from about 7 (live animal pH) to the level, typically 5.5, at which it will not fall any further (known as the ultimate pH) against the temperature of the carcass. There is an ideal 'window' that describes the ideal relationship between carcass pH and temperature from slaughter to when ultimate pH is reached. If the rate of pH- temperature decline does not fall through the ideal window, the quality of the meat obtained from the carcass can be compromised. By deriving information of carcass pH using the present invention, and combining with conventional temperature sensing, the present invention allows the monitoring and recording of a pH-temperature history for carcasses, which can be progressively checked in real-time or close to real-time against the ideal window.

The above application can be implemented as part of the usual electrical stimulation process, or independently with no, or minimum, effect on the pH of the carcass. The latter may be used in circumstances when stimulation is not desired but, instead, pH needs to be measured to assure that the pH-temperature history fits within a defined specification, such as the ideal window.

The present invention may also be used to predict the ultimate pH. That is to say, the information obtained using the present invention may be utilised to predict the pH that the carcass will reach in the end.

Attributes of tenderness may also be predicted from the response characteristics of carcasses. For instance, initial tenderness, which is the tenderness at rigor mortis, and the rate of tenderisation may be predicted. A prediction on the rate of tenderisation may be used to control how the carcass, or meat from the carcass, is further processed. For instance, if the rate of tenderisation is predicted to be high, the carcass or its meat will be distributed locally, so that it is sold and consumed within a relatively short time frame. If the rate of tenderisation is predicted to be low, the carcass or its meat will be chilled and shipped internationally so that the delay in transportation allows optimum tenderisation.

Given the above, the present invention in its basic form facilitates effective processing of carcasses whereby insufficient or excessive electrical stimulation is avoided. In other words, the present invention provides effective mechanisms to produce, consistently, a level of stimulation that forms a critical part of effective processing for high value markets. In particular, the present invention allows the production and control of stimulation that provide tailored levels of pH decline to allow the pH-temperature decline to be optimised for specific markets of product types.

The present invention may be adapted for use independently of any other apparatus or systems, or may be adapted for use with one or more known apparatus or systems. As a non-limiting example, the present invention may be adapted for use with the master computer described in relation to the electrical stimulation system of US Patent No.

7,025,669. In particular, the present invention may be used to provide information relating to the pH level of the carcass for use by the system in improving the processing of carcasses and thus the quality of meat obtainable from the carcasses.

The foregoing describes the invention including preferred forms thereof. Alterations and modifications as will be obvious to those skilled in the art are intended to be incorporated within the scope hereof. For example, the components illustrated schematically for the preferred form apparatus and system of the invention need not necessarily be in the form illustrated. One or more of the components may be incorporated together to function as a single component. Alternatively, any one component illustrated may be implemented using two or more components.

Claims

CLAIMS:

1. A method of determining the pH of a carcass or part thereof, the method comprising: stimulating the carcass with an electrical test signal; measuring the response of the carcass to the test signal; deriving a set of response data values obtained from measuring the response of the carcass; and determining the pH of at least part of the carcass from the set of response values.

2. The method of claim 1 wherein the electrical test signal comprises one or more predetermined electrical pulses.

3. The method of claim 1 wherein the electrical test signal comprises one or more sets of predetermined electrical pulses.

4. The method of any one of the preceding claims wherein the response of the carcass comprises the force of contraction of the carcass muscles during stimulation of the carcass with the electrical test signal.

5. The method of any one of the preceding claims wherein the response of the carcass comprises the rate of relaxation of the carcass following stimulation of the carcass with the electrical test signal.

6. The method of claim 5 or claim 6 further comprising suspending the carcass from a load cell and stimulating the carcass with the electrical test signal while suspended.

7. The method of claim 6 wherein the set of response data values comprises a sequence of load cell responses at different time values.

8. The method of claim 7 wherein determining the pH further comprises: extracting one or more frequency components from the set of response data; and calculating the pH from the product of the frequency components and a set of stored coefficients.

9. The method of claim 8 wherein the set of stored coefficients are obtained from regression analysis on the frequency components and measured pH values.

10. A method of reducing the pH of a carcass or part thereof, the method comprising:

(a) determining the pH of the carcass by the method of any one of the preceding claims;

(b) comparing the determined pH with a stored target pH value;

(c) stimulating the carcass with an electrical corrective signal if the determined pH is greater than the stored target pH value;

(d) repeating steps (a) to (c) until the determined pH is less than the stored target pH value.

11. The method of claim 10 wherein the frequency of the corrective signal is greater than the frequency of the test signal.

12. The method of any one of the preceding claims further comprising selecting the frequency of the test signal to have minimal effect on the pH of the carcass.

13. A carcass pH determination system comprising: an electrical signal generator configured to generate an electrical test signal to stimulate the carcass or part thereof; one or more sensors configured to measure the response of the carcass to the test signal; and a processor configured to receive a set of response data values obtained from the sensor(s) and to determine the pH of at least part of the carcass from the set of response values.

14. The system of claim 13 wherein the response of the carcass measured by the sensor(s) comprises the force of contraction of the carcass muscles during stimulation of the carcass with the electrical test signal.

15. The system of claim 13 or claim 14 wherein the response of the carcass measured by the sensor(s) comprises the rate of relaxation of the carcass following stimulation of the carcass with the electrical test signal.

16. The system of claim 14 or claim 15 wherein at least one of the sensors comprises a load cell from which the carcass is suspended.

17. The system of claim 16 wherein the set of response data values comprises a sequence of load cell responses at different time values.

18. The system of any one of claims 13 to 17 wherein the electrical signal generator comprises a constant electrical stimulation device.

19. The system of any one of claims 13 to 18 further comprising one or more electrodes positioned to contact the carcass and to thereby deliver the electrical test signal to the carcass.

20. The system of any one of claims 13 to 19 further comprising a Fast Fourier transform device configured to extract one or more frequency components from the set of response data.

21. The system of claim 20 further comprising a set of stored coefficients maintained in computer memory, the processor configured to calculate the pH from the product of the frequency components and the stored coefficients.

22. The system of claim 21 further comprising a regression analysis component configured to derive the stored coefficients from regression analysis on the frequency components and measured pH values.

23. A carcass pH reduction system comprising: an electrical signal generator configured to generate an electrical test signal while in a test mode and to generate an electrical corrective signal while in a corrective mode; one or more sensors configured to measure the response of the carcass to the test signal and to generate a set of response data values; a pH determination component configured to determine the pH of at least part of the carcass from the set of response values; a comparator configured to compare the determined pH with a stored target pH value; and a processor configured to place the signal generator in the corrective mode to generate an electrical corrective signal.

24. The system of claim 23 wherein the response of the carcass measured by the sensor(s) comprises the force of contraction of the carcass muscles during stimulation of the carcass with the electrical test signal.

25. The system of claim 23 or claim 24 wherein the response of the carcass measured by the sensor(s) comprises the rate of relaxation of the carcass following stimulation of the carcass with the electrical test signal.

26. The system of claim 24 or claim 25 wherein at least one of the sensors comprises a load cell from which the carcass is suspended.

27. The system of claim 26 wherein the set of response data values comprises a sequence of load cell responses at different time values.

28. The system of any one of claims 23 to 27 wherein the electrical signal generator comprises a constant electrical stimulation device.

29. The system of any one of claims 23 to 28 further comprising one or more electrodes positioned to contact the carcass and to thereby deliver the electrical test signal to the carcass.

30. The system of any one of claims 23 to 29 further comprising a Fast Fourier Transform device configured to extract one or more frequency components from the set of response data.

31. The system of claim 30 further comprising a set of stored coefficients maintained in computer memory, the processor configured to calculate the pH from the product of the frequency components and the stored coefficients.

32. The system of claim 31 further comprising a regression analysis component configured to derive the stored coefficients from regression analysis on the frequency components and measured pH values.

33. The system of any one of claims 23 to 32 wherein the frequency of the corrective signal is greater than the frequency of the test signal.

34. The system of any one of claims 23 to 33 further comprising an input device, the input device configured to obtain input from a user directing the processor to generate either a test signal or corrective signal.

35. The system of claim 34 wherein the input device is further configured to obtain the stored target pH value from the user.

36. The system of any one of claims 23 to 35 further comprising a display configured to display to a user the determined pH.