SU1666949A1 - Method for checking meat freshness - Google Patents

Abstract

The invention relates to the meat industry, can be used in controlling the freshness of meat to determine its suitability for further use. The aim of the invention is to improve the accuracy. The sample of meat is compressed to a predetermined deformation value of 0.3, followed by registration after the loading device stops changing the relaxing stress over time. The degree of freshness of meat is judged by the magnitude of the ratio of the final relaxation voltage to the initial one on the basis of a comparison with the reference values obtained under the same conditions. M s is considered fresh when the freshness value is above 0.55, doubtful freshness is from 0.55 to 0.4, stale - below 0.4. 3 il. 3 tab.

Description

The invention relates to the meat industry, in particular, to methods for controlling the freshness of meat to determine its suitability for further use.

The purpose of the invention is to improve the accuracy of control.

FIG. 1 shows an apparatus for carrying out the method; in fig. 2 - dependence of the change in the relative deformation (E) on the stress (o) in the process of uniaxial compression of the test sample of cooled meat (); in fig. 3 shows the dependence of the change in the acoustical characteristics of muscle tissue in determining the degree of freshness.

The device contains a movable 1 and a fixed 2 rigid metal plates for compressing the sample, a loading device 3 with a mechanism for moving the movable plate 1 at a predetermined speed, a strain gauge 4 and a load cell with a strain gauge 5.

The method is implemented as follows.

A sample of a given size is placed between plates 1 and 2 and compressed using a loading device 3 to a predetermined strain value, which is controlled by strain gauge 4. At this moment, the loading device is fixed and for a predetermined time the relaxation voltage drop is measured using a force meter with a strain gauge 5 by recording the initial value of the relaxation voltage after fixing the loading device and the final value of the relaxation voltage.

about oh yu

cut 60 seconds after the termination of the compressive load.

The method is based on the use of experimental data obtained in the study of the viscoelastic properties of muscle tissue of cattle and allowing to derive the reference values of the ratio of final and initial relaxation stresses for meat of different degrees of freshness. This method of control is valid only for chilled half carcasses ma at + 4 ° C in the thickness of the muscles.

Samples of cylindrical maca with a diameter of 28 mm and a height of 15 mm, cut with a special device across muscle fibers, are kept at 4 ° C for eight days after slaughtering an animal, taking pieces for analysis every day,

The freshness of samples of meat is determined at relative deformation values (c) of 0.3; relaxation time (t) 60 s, as well as organoleptic and chemical methods.

The specified parameter values are based on the following premises.

- a practically linear relationship between stress and strain in the strain range from 0 to 0.3 allows one to use the linear relations of the theory of hereditary viscoelasticity, i.e., to simulate mathematically the relaxation process;

-the study duration of 60 s characterizes the established relaxation process, when the rate of change of relaxation stresses practically tends to zero;

- chilled meat, which, due to its high quality indicators, is widely used under production conditions, has a temperature inside the muscle tissue of 4 ° C.

Samples of fresh meat (determined organoleptically) after 1-2 days of storage had an OK / CJH freshness ratio (the ratio of the final relaxation voltage to the initial) in the range from 0.57 to 0.69.

Samples of meat of doubtful freshness (determined organoleptically) after 4-5 days of storage had a freshness index in the range from 0.42 to 0.52.

Samples of fresh meat (determined organoleptically) after 7-8 days of storage had a freshness index in the range from 0.33 to 0.39.

In order to clarify the boundary values of the freshness index for fresh and stale meat, the chemical method of analysis by the amount of volatile fatty acids (1) was used, since the organoleptic did not give an unambiguous assessment.

After 3 days of storage, samples of meat had a freshness index of 0.55 ± 0.02, and the content of volatile fatty acids was 3.99 ± 0.01 mg of potassium hydroxide per 25 g of meat.

After 6 days of storage, samples of meat had a freshness index of 0.40 ± 0.02, and the content of volatile acids was

9.00 ± 0.01 mg of potassium hydroxide per 25 g of meat.

Thus, m with different degrees of freshness has the following values of freshness indicator:

Fresh over 0,55

Doubtful freshness 0.40–0.55 Lower than 0.40.

The level of relative deformation (Ј) at the moment of stopping the loading device is essential for the implementation of the method. A relative deformation of 0.3 is optimal for obtaining complete and correct data when examining samples having positive temperatures. Increasing the value of relative deformation above 0.3 leads to the destruction of muscle fibers, which entails errors in the evaluation of their behavior. Quality control of the studied

specimens with values of relative deformation below 0.3 gives a less accurate estimate of the viscoelastic state of the muscle tissue due to a wide range of data.

The dependence of the change in the relative deformation (E) on the stress (o) in the process of uniaxial compression of the sample of cooled meat () is shown in FIG. 2

In the first zone (Ј 0,2) is observed

Significant deformation of specimens of small-scale small loads, and in the lateral direction, m c is deformed mainly across the fibers, which can be explained

smoothing the irregularities of the contacting surfaces of the samples and redistributing the fibers.

For the second zone (0.2 Ј 0.4), there is a typical linear plot on the graph

Lateral deformation occurs predominantly along the fibers. Increased load is required. There is a slight excretion of tissue fluid.

In the third zone (~ 0.4), the deformation in the direction of compression is reduced, there is a strong release of tissue fluid, the destruction of the fibers.

The nature of the change in the elastic elastic characteristics of muscle tissue in determining the degree of freshness of the proposed method is depicted in FIG. 3. In zone A, a change in the compressive stress (o) of samples of meat of various degrees of freshness is shown up to a given value of 0.3. In zone B, the change in stress relaxation (o) with time at Ј -0.3-const. At Ј 0.2, a less reliable estimate of the viscoelastic properties of the muscle tissue is obtained due to the difficulty of accurately recording the values at the moment when the loading device is stopped.

Example 1. A sample of meat taken from the cooling chamber of meat was examined under the same conditions by the proposed method and organoleptically.

The compressive force of the specimen at the moment of stopping the loading device is .6H.

The compressive force of the sample through 60 with RK-16.22N,

Freshness rate

gtAt fK / S 16.22

a / a -1 7s-vM-0

where S is the sample surface area, m

The freshness indicator makes it possible to evaluate the investigated mixture as fresh. Organo-leptic control confirms this.

EXAMPLE 2 A sample of meat taken from a chilled meat storage chamber was examined as in Example 1.

In organoleptic control, disagreements arose in assessing the freshness of meat: either fresh or doubtful freshness. The definition of the freshness indicator allowed us to conclude that it is doubtful freshness, because OK / OH is 0.51; (, 91H:, 70H).

PRI me R 3. A sample of obvious signs of damage was investigated similarly to examples 1 and 2.

On the basis of the organoleptic control, after some fluctuations, the m s is recognized as questionable freshness. However, the definition of the freshness indicator made it possible to correct the error, estimating it as stale because OK / OH is -0.39; (, 13H; P "-9.42N).

Thus, to obtain accurate and reliable research data

It is necessary to carry out at optimum relative deformation Е-0,3. Examples are presented in table. 1. For consistency, samples of moderate freshness were selected, aged at 4 ° C for 4 days. Relaxation time 60 sec.

The duration of the control, which characterizes the steady-state relaxation process, is chosen to be 60 s, when the rate of change of voltage almost tends to zero. When studying dependencies of this kind (Fig. 3, zone B), the duration of the measurement can be limited based on the condition: the modulus of the difference between the last (Ok / o) i) and the penultimate (Ok / o) s values of the desired indicator at the appropriate times t R | - 1 must not exceed the error of the method for performing the change (Doc / a), i.e.

/ Pjl / ° L

00) Vo-cJl-1

D

Ok ob

ABOUT)

25o

where D is calculated as RMS (7 °

The actual measurement deviation of a single sample according to the formula (2):

thirty

at t № - №

OK | 1 OoJI 0a

L0o 1P

(2)

(UK - n is the measurement value of the measurement of one sample at a given (t) point in time;

(- - the average value is parallel /

0 measurements of one sample f p - the number of measurements. Calculated by the formula (2), the error of the measurement procedure for a sample of questionable freshness at. , 3;

g 60s, n 6, amounted to D-. - 0.01 (tab. 2).

oh

In order to clarify the duration of the operation to control the freshness of meat in the time interval from 40 to 70 s, the indicators of freshness were obtained every 10 0 s for a similar sample of meat (Table 3), the moduli of their differences were calculated and carried out

comparison with the formula (1).

I / o

5 Thus, the duration of control must be at least 60 s.

When using this instrumental method, only its initial calibration is performed, i.e. each

the numerical value of the freshness indicator is matched to the description on a scale of desirability and gradation in points. The use of this calibration scale improves the accuracy of the assessment and removes subjective errors.

Claims (1)

Claims The method of controlling the degree of freshness of the meat, which involves compressing the sample of the meat to a predetermined strain value, followed by recording the change in the relaxed stress over time after the compressive load ceases to apply and establishing a freshness indicator correlating to the degree of freshness of the meat that differs from that, in order to increase the accuracy, the reference values of the freshness indices for samples of meats of different degrees of freshness, given the deformation value is set equal to 0.3 and at the moment of its achievement the loading device is fixed with simultaneous registration of the initial value of the relaxing voltage, the final value of the latter is recorded 60 seconds after the compressive load is terminated and the value of the final stress value is determined relaxation to the initial, while as a measure of freshness, correlating with the degree of freshness of meat, use the set value of the ratio, and trol carried out by comparing current values with predetermined index of freshness, and chilled meat fresh feel at a value above the index of freshness 0.55 dubious freshness - 0,55-0,4, stale - below 0.4. Table Table 2 Table3 g YZ2ZL /// 7 ////////////// Figure 1 W tfy 7 eight five C 3 I 0.1 0.1 0.3 O.b 0.5 Dependence of change on the 6- & $ uniaxial compression process 9ig.2 .z EEE3 ati x „° a J 0, Z 10 7d JO To SO60 The nature of the change in b zhourrushh characteristics (b -6-Z) muscular end of varying degrees of sat and weight FIG. J