RU2685197C1 - Method for long-term storage of frozen meat - Google Patents

Abstract

FIELD: food industry.SUBSTANCE: invention relates to the meat processing industry, and in particular to methods of long-term storage of frozen meat in an inert gas environment. Method involves keeping the meat in the refrigerating chamber at low temperatures for 18–20 months, followed by a gradual increase in temperature. Helium is used as a coolant, which is cooled by adiabatic expansion. Keeping the meat and cooling thereof is carried out in two stages: within two weeks the temperature is lowered to -35 °C, in the next two weeks the temperature is lowered to -50 °C, after 18–20 months, the temperature is gradually increased to -10 °C during a month. During the whole process, helium is separated from the air, reducing oxidative processes in the meat, the temperature inside the refrigerating chamber is regulated by changing the pressure created by the compressor. Day before the temperature is raised to -8 °C, helium is taken away and replaced with air.EFFECT: increased shelf life of meat without loss of quality.1 cl, 1 dwg, 1 ex

Description

The invention relates to refrigeration technology, and in particular to methods of long-term storage of frozen meat in an inert gas environment, at a constant low temperature.

There is a method of storing meat by freezing it and holding it at a temperature of (-18) - (- 30) С ° for 4-5 months and then storing it until it is sold at a temperature (-10) - (- 12) С ° (certificate of authorship SU # 544413, 1975). The disadvantage of this method is the complexity of the required analysis at different operations of the method and a long period of aging at low temperatures.

The closest to the proposed solution is a method of storing meat products providing for its aging in a chamber at (-25) - (- 30) C ° followed by an increase in temperature (certificate of authorship SU №1340712, 1984). The disadvantage of this method is the high energy costs of cooling and maintaining ice screens.

Technical problem - the creation of a method that provides long-term storage of frozen meat by maintaining low temperatures and the use of an inert environment inside the refrigerating chamber.

The technical result is an increase in the shelf life of meat without loss of quality.

It is achieved by the fact that in the known method of keeping meat in the refrigerating chamber at low temperatures for 18-20 months, followed by a gradual increase in temperature, helium is used as a refrigerant, which is cooled by detuning, and the meat is kept cool and cooled. stage: within two weeks the temperature is lowered to (-35) ° C, over the next two weeks the temperature is lowered to (-50) ° C, after 18-20 months the temperature is gradually increased to (-10) ° C during the month, during all The helium process is separated from the air by reducing the oxidation processes in the meat, the temperature inside the refrigerating chamber is regulated by changing the pressure created by the compressor, the day before the temperature is raised to (-8) ° C, helium is selected and replaced by air.

Helium is used as a medium for storing meat, in order to reduce its damage due to its bioinertness and the lowest chemical activity. The use of expansion, which returns part of the work expended, results in lower energy costs. Keeping the meat at (-50) ° C ensures simultaneous preservation of the meat and the optimum maintained helium temperature during cooling on the expanders. Separation of helium from air is necessary to ensure a homogeneous environment inside the refrigerating chamber.

The method is as follows:

In the freezer with a loading capacity of 600 tons, 581 tons of frozen meat with a temperature in the thickness of the muscles are loaded at (-10) ° C, helium is used, which is cooled by detandering, and the temperature is adjusted to (-50) ° C in 1 stage in 1 month within 2 weeks the temperature is reduced to (-35) ° C, then within 2 weeks to (-50) ° C. The meat in the freezer is kept in a helium environment for 18-20 months at a constant temperature (-50) ° C. After 18-20 months, the temperature is gradually increased to (-10) ° C during the month, during the whole process helium is separated from the air, reducing oxidative processes in meat. The day before the temperature is raised to (-8) ° C. Before opening the refrigerating chamber, they take helium from the refrigerating chamber and the cooling system and replace it with air, they are replaced through the receiver. Then the meat is removed from the freezer for sale. Helium, purified from impurities, can be repeatedly used to implement the method

An example of the method:

After laying 581 tons of meat into the refrigerating chamber with a loading capacity of 600 tons, helium is supplied to the volume of the refrigerating chamber, which is cooled by expansion. Cooled helium ensures the safety of the meat inside the refrigerator, and cooling of helium due to the pressure drop on the expanders ensures the stability of maintaining the required temperature inside the freezer. Within 1 month of exposure, the temperature is lowered to (-50) ° C. in two stages: within 2 weeks the temperature is reduced to (-30) ° C, then within 2 weeks to (-45) ° C.

After 18-20 months, a month before the product is sold, the temperature inside the refrigerating chamber is gradually raised to (-10) ° C, by reducing the pressure created by the compressor, helium is separated from the air during the whole process, thereby reducing oxidation processes meat.

Before opening the refrigerating chamber, they take helium from the refrigerating chamber and the cooling system, replace it with air, and replace it with a receiver.

Then during the day the temperature inside the freezer is raised to (-8) ° C. Then the meat is removed from the freezer for sale.

For the implementation of the method using gas refrigeration systems, equipped with a membrane gas separation module.

The drawing shows schematically a cooling chamber for the implementation of the proposed method.

The device contains a gas refrigerating chamber 1, a receiver 2, an expander 3, a compressor 4, a heat exchanger 5, a refrigerating chamber 1 is additionally equipped with a membrane gas separation module 6 separating helium from air. The meat inside the refrigerating chamber 1 is cooled by helium, with the help of the expander 3 and the pressure generated by the compressor 4.

Helium from receiver 2 enters compressor 4, then helium is compressed in compressor 4 and passing through heat exchanger 5 is fed to expander 3, where it is cooled, performing work due to pressure drop, then helium enters refrigeration chamber 1, cooling meat, then helium from the refrigerating chamber 1 enters the membrane gas separation module 6, where it is separated from the air, and again enters the compressor 4 and the cycle repeats. The air from the membrane gas separation module 6 is discharged into the atmosphere through channel 7.

Low temperature (-50) ° С and low gas circulation rate inside the refrigerating chamber, as well as a high degree of congestion of the refrigerating chamber, reduces the evaporation of moisture from the surface of the meat, reducing the drying of the meat. The moisture content of meat for the entire storage period decreased by an average of 0.8-0.9%.

The group composition of frozen meat lipids undergoes minor changes. When freezing to (-35) ° C and further lowering the temperature to (-50) ° C, the degree of evaporation of moisture and migration of moisture to the surface from the deep layers of meat decreases.

Thus, with the help of cooling and the content of frozen meat in an inert gas (helium) environment, increase the duration of its storage, with the lowest energy costs.

A positive effect - the proposed method increases the shelf life of frozen meat, allows you to save as much as possible inert gas and requires little expenditure on the work of the necessary installation.

Claims (1)

The method of long-term storage of frozen meat, providing for keeping the meat in the refrigerating chamber at low temperatures for 18-20 months, followed by a gradual increase in temperature, characterized in that helium is used as the refrigerant, which is cooled by expansion, the keeping of the meat and its cooling is carried out in two stage: within two weeks the temperature is lowered to -35 ° C, in the next two weeks the temperature is lowered to -50 ° C, after 18-20 months the temperature is gradually increased to -10 ° C over the course of two weeks. yatsa, during the whole process, helium is separated from the air, reducing oxidative processes in the meat, the temperature inside the refrigerating compartment is controlled by changing the pressure generated by the compressor, per day to implement the temperature was raised to -8 ° C, helium is withdrawn, replacing it with air.

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