RU2239829C2 - Method of estimation of freshness of meat products - Google Patents

Abstract

FIELD: meat industry; methods of estimation of freshness of meat products both in laboratories and at production plants.

SUBSTANCE: proposed method includes selection of sample followed by grinding this sample, extraction, centrifuging, boiling-off, chromatographic separation in chambers filled with mixture of acetone and concentrated ammonia at ratio of 18:3, dyeing, determination of concentration of biogenic amines by means of computer program Scion Image of treatment of data of thin-layer chromatography and relating the definite concentration to definite degree of freshness of meat products. Concentration of biogenic amines is determined on basis of concentration of cadaverine (their example).

EFFECT: facilitated procedure; reduced labor consumption; enhanced accuracy.

2 tbl, 2 ex

Description

The invention relates to the meat industry and can be used for an objective assessment of the quality and freshness of meat raw materials.

It is known that if the conditions and storage periods are not met, fresh meat acquires the properties of meat of dubious freshness and stale.

For the production of products intended for food purposes, use only fresh meat. Meat of dubious freshness is subjected to research, and only after appropriate processing can it be used for food purposes.

To control the quality and safety of raw meat and meat products, it is necessary to develop an accurate, objective method for determining the freshness of meat.

There are several ways to assess the freshness of meat, it is evaluated:

- organoleptic assessment (GOST 7269-79 Meat. Methods of sampling and organoleptic methods for determining freshness);

- breakdown with copper sulfate, determination of volatile fatty acids, microscopy of smear-prints of test samples (GOST 23392-78 Meat. Methods of chemical and microscopic analysis of freshness);

- histological assessment (GOST 19496-93 Meat. Method of histological examination, GOST R 51604 - 2000 Meat and meat products. Method of histological identification of composition).

An organoleptic assessment of the freshness of meat involves the determination of:

- appearance and color,

- consistency,

- smell

- state of fat,

- transparency and aroma of the broth.

The method of chemical analysis is based on the allocation of volatile fatty acids accumulated in meat during its storage, with the determination of their amount by titration of the distillate with potassium hydroxide.

Another method (using copper sulfate) determine the products of the primary breakdown of proteins in the broth.

The method of microscopic analysis is based on determining the number of bacteria and the degree of decomposition of muscle tissue during microscopy of smear prints.

A histological examination of the freshness of meat is carried out by examining the prepared histological preparations under a microscope. The degree of freshness is determined by indicators:

- the state of the structure of the nuclei of muscle fibers,

- the state of transverse and longitudinal striation of muscle fibers,

- localization of microflora and the boundaries of its distribution.

Compare the micro-picture of the structural changes of meat with the standard.

Existing laboratory methods often give conflicting results. The main disadvantages of the methods of organoleptic assessment of freshness and evaluation of breakdown with copper sulfate are their subjectivity and lack of accurate digital data.

The disadvantages of smear microscopy of fingerprints and determination of the content of volatile fatty acids are their inaccuracy and unstable results. Over the past decades, the conditions of animal feeding have changed, and therefore the qualitative characteristics of meat have undergone changes and sometimes do not correspond to prevailing ideas.

The histological assessment of meat is one-sided and can only be applied in a comprehensive study as its component and is not always acceptable for practical use due to the lack of special equipment in the production environment. This makes the assessment of meat freshness largely subjective, and in practical work with a conflict of interest, disagreements on the results of tests may arise.

In addition, the current methods for assessing the freshness of raw meat can include such disadvantages as the duration of the research and the complexity.

Freshness of meat is directly related to its microbial contamination, as in the process of their life, microorganisms secrete enzymes into the substrate that cause protein breakdown. A number of substances resulting from biodegradation of meat can act as rapper substances, the presence and quantity of which can serve to test freshness. These substances include biogenic amines (substances formed during the decarboxylation of amino acids), which should be mentioned primarily cadaverine, putrescine and histamine. In the course of our research, it was found that the most appropriate is the assessment of the freshness of raw meat by cadaverin, because the concentration of putrescine is slowly increasing, which creates problems with the differentiation of different degrees of freshness, and the concentration of histamine in the process of microbial spoilage may even decrease.

A known method for assessing the freshness of food raw materials, such as fish, by determining biogenic amines, in particular histamine, characterizing microbial spoilage of fish, which involves extraction, centrifugation, chromatographic separation, staining and concentration estimation (see Lieber ER, Taylor SR “Thin-layer chromatographic screening metods for histamine in tuna fish ”Journal of chromatography, vol. 153, 1978, p. 143-152).

The disadvantages of the above method include its inappropriateness to raw meat, duration in terms of chromatographic separation, as it is suitable for the determination of histamine. In addition, the quantitative determination of the content of biogenic amines is carried out by visual assessment, and also this method does not allow to determine clear boundaries of freshness.

The technical result achieved by using the invention is to accelerate the process, reduce the complexity, increase the accuracy and the ability to accurately distinguish between different degrees of freshness.

This is achieved by the fact that the method for assessing the freshness of meat raw materials involves sampling the raw material, its grinding, extraction, centrifugation, evaporation, chromatographic separation of the obtained extract by one-dimensional run on thin-layer silica gel plates in chromatographic chambers filled with a mixture of acetone and concentrated ammonia in a ratio of 18: 3 , staining, determination of the concentration of biogenic amines using the Scion Image computer program for processing thin-layer chromatography data and assignment of determination elyaemoy concentration to a certain degree of freshness of raw meat, based on the set values, the concentration of the biogenic amine is determined based on the concentration of cadaverine - their representative.

The use of a mixture ratio of 18: 3, not 18: 1 (as in the method for determining the freshness of fish) accelerates the separation process by 2 times.

Using for quantitative determination of a computer program allows you to get more reliable data, expressed in digital form, and the exact separation of different degrees of freshness allows you to accurately determine the different stages of damage.

Example 1

Extraction

50 ml of methanol are added to 10 g of the ground meat meat sample and homogenized for 3 minutes. The resulting homogenizate after exposure to a water bath is centrifuged for 10 min at 2000-3000 rpm, the upper layer is separated. The extract obtained after centrifugation is evaporated in a water bath at 80 ° C to 5-10 ml (5 ml for pork, 10 ml for beef). Then the extract is cooled to room temperature.

Cooking standards

Standards: 102.8 mg of cadaverine dihydrochloride is dissolved in 4 ml of distilled water and adjusted to a volume of 20 ml with methanol. The result is a standard solution with a concentration of pure cadaver 3 mg / ml. The solution is stored in the refrigerator. Before use, it is diluted with a mixture of methanol with distilled water (8: 2) and as a result, working standards with a cadaverine content of 0.2 are obtained; 0.1; 0.05 and 0.005 mg / ml.

Distillation of standards and extracts

10 μl of the obtained extract and working standards are applied to a plate for thin layer chromatography. The plate with the applied extracts and working standards was placed in chromatographic chambers filled with a mixture of acetone and concentrated ammonia (18: 3) and incubated for 2 hours.

The plate is dried under traction until the smell of ammonia disappears.

Staining.

The plate is sprayed with a ninhydrin solution (300 mg of ninhydrin are dissolved in 100 ml of butanol with the addition of 3 ml of glacial acetic acid). The plate is dried and incubated for 5 min at 100 ° C.

Cadaverine Concentration Assessment

Next, the plate with the obtained spots is immediately scanned, and the spots are evaluated for cadaverine content in them using the Scion Image computer program for processing thin-layer chromatography data (the obtained data for pork are divided by 2).

Freshness rating

According to the content of cadaverine mg / kg, the sample is attributed to a certain degree of freshness, based on the established values shown in table 1.

Example 2

Practical application.

As samples for the experiment, we used beef and pork stored at a temperature of 20 ° C. Samples were taken from the samples at the beginning of storage (samples No. 1), after 1 day (samples No. 2), after 2 days (samples No. 3) and after 3 days (samples No. 4). All beef and pork samples were tested for cadaverine content. The research data on the content of cadaverin are shown in table 2.

Further, the samples were investigated by their organoleptic characteristics (as the most reliable method). Samples No. 1 and 2 for beef and No. 1 pork were classified as fresh meat, sample No. 2 of pork was of doubtful freshness, both samples No. 3 were assigned to meat of doubtful freshness, samples No. 4 were assigned to stale meat.

From the data in the table and comparing these data with organoleptic evaluation, we can conclude that the claimed method is objective, and in contrast to organoleptic evaluation, it ultimately has a quantitative result.

Claims (1)

A method for evaluating the freshness of meat raw materials, which includes sampling raw materials, their grinding, extraction, centrifugation, evaporation, chromatographic separation of the obtained extract by run on thin-layer silica gel plates in chromatographic chambers filled with a mixture of acetone and concentrated ammonia in a ratio of 18: 3, staining, determination of concentration nutrient amines using the Scion Image computer program for processing thin-layer chromatography data and assigning the determined concentration to a certain th degree of freshness of raw meat, based on the set values, the concentration of the biogenic amine is determined based on the concentration of cadaverine as a representative.