DK173153B1 - Method and system for cooling slaughter heat pig carcasses - Google Patents

Description

The present invention relates to a method and system for cooling slaughter heat pig carcass parts for cooling temperature.

in DK 173153 B1

The suitability of a cooling method is contingent upon an interplay between i.a. type of refrigerant, working temperature of the refrigerant, flow profile around the product to be cooled, product orientation relative to flow, product weight and form, product sensitivity to cold shock and freezing, the start and end temperature, and the time available.

If the factors do not coincide, the method is unsuitable for cooling the product.

Today, slaughter-heat pig carcasses are cooled with cold air by an intensive process in which half carcasses, in pairs suspended in a hinge, are passed through a cold room, while cold air is blown on the bodies. Intensive air cooling (the so-called tunnel cooling) is distinguished by keeping the cooling wind and PSE frequency down, but is extremely energy intensive. It is also common for pig carcasses to be cooled batchwise in cold rooms with an air temperature of e.g. + 1 ° C. This process is not as energy intensive as tunnel cooling, but the cooling time is considerably longer and the cooling wind is higher.

Danish Patent No. 104,964 discloses a method of cooling purified poultry in which poultry bodies are passed through two elongated vessels with stirred, cold tap water. The second of these vessels is added ice so that the temperature is kept at approx. + 1 ° C. When the bodies are completely cooled after Vi hour, they are transported directly to the packing department. Significant cross-contamination occurs between the poultry bodies.

Danish Patent No. 30,173 relates to a method of freezing e.g. chilled meat and fish by immediate treatment with a heavily cooled brine containing e.g. 15% boiling salt and up to 20% glycerol. This liquid is cooled to a temperature of 2-7 ° C below the freezing point of the saline solution, ie. to well below -20 ° C. European Patent No. 194,313 discloses another method for freezing cold food portions in which the 25 portions are immersed in a brine with a temperature below -20 ° C. Prior to freezing, each batch is packaged in a plastic bag and can be stored or distributed immediately after freezing.

DK 173153 B1 2

It is an object of the invention to provide a new method and system for cooling slaughter pig pig carcass parts which require substantially less energy than the above tunnel cooling process, has a significantly shorter cooling time than the other cooling processes mentioned above, and avoids cross-contamination at the same time as a conventional cold .

This object is achieved by the method according to the invention, characterized in that the carcass parts are individually wrapped in a foil, that the enclosed carcass parts are immersed in a refrigerant in the form of brine or soap with a temperature between -2 and -20 °. C, that relative movement between the refrigerant and carcass parts is provided, that the carcass parts are kept in the refrigerant until they are frozen, and have delivered a heat amount to the refrigerant mainly corresponding to the cooling of the carcass parts from the carcass to cool temperature, the carcass parts being taken up, the film is then removed and the carcass portions finally allowed to offset temperature differences.

The method of the invention has significant advantages over the intensive air cooling (tunnel cooling) for cooling carcass parts. The cooling method requires significantly less energy, as it has been found that energy consumption can be reduced by approx. 50% compared to traditional, intensive air cooling of carcasses. In addition, the cooling time for carcasses of pig carcasses can be significantly shortened, e.g. with up to 30% when used must freeze the carcasses.

The process according to the invention has a considerably shorter cooling time than batch cooling of carcasses in cold air cold rooms or in ice-water vessels.

The method according to the invention results in a substantially lower cooling wind than both tunnel cooling and batch cooling, and furthermore cross-contamination between the bodies is avoided.

In addition, it has been found that in the method according to the invention, it is unnecessary to use special flow engineering measures to obtain good heat transfer from the carcass portion to the refrigerant. At relative flow rates between the carcass parts and the refrigerant between 0.05 and 0.2 m / s, cooling times can be obtained for half of the pig carcasses in 60 minutes and less. This can be achieved by passing the half carcases through the refrigerant at a rate corresponding to the usual transport speed of a slaughter line.

The coolant used in the form of brine or soap ice has a high cooling capacity and a high thermal conductivity, which allows the use of higher operating temperatures than in tunnel cooling, since the heat transmission is much higher than for air.

In the present invention, brine means aqueous solutions of solids, e.g. salts, or mixtures of water and organic liquids, e.g. glycols or alcohols (or combinations of solutions and mixtures). Brine has the property of being antifreeze 10 at temperatures below 0 ° C and e.g. can operate at -7 ° C without freezing.

The brine removes the heat of the product during temperature rise and must therefore be cooled by means of a cooling system. Brine is advantageous in that it is easy to cool in an external cooling system.

In the present invention, by ice is meant either an aqueous solution of solids or a mixture of water and organic liquids containing an ice fraction in the form of particles (or 15 combinations of solutions and mixtures with ice particles). Ice-cream has the property of being able to flow at temperatures below 0 ° C (at the working temperature). Preferably, the ice cream does not contain larger ice portions than it is easily flowable and can be pumped effortlessly. Preferably, ice cream is used with fine ice particles that keep floating, see e.g. WO-A1-9627298 (Danish Technological Institute).

20 Ice-cream removes heat from the product by phase-converting ice to water and therefore has a large cooling capacity. Soap ice has excellent thermal properties (latent heat of melting) and also exhibits good mixing properties (stays homogeneous and fluidized).

Binary ice-cream mixtures are in practice zeotropic, i.e. that phase conversion from solid to liquid form takes place in a temperature range.

DK 173153 B1 4

Soap ice provides a number of advantages over brines, such as better operating economy, energy storage and less environmental impact (higher COP value; COP = coefficient of performance (kW cooling / kW electricity consumption)). Due to the ice content of the ice cream, a very large cold performance can be stored in a relatively small volume. This enables the production of cold during the 5 night hours, where the electricity tariff is low. The night operation can typically be carried out at lower condensing temperatures with the consequent improvement of COP, and the compressor can operate under constant and optimal conditions. Night operation means investing only in half the cooling capacity, since the same amount of cold can be produced at twice the time.

Although no night operation is used, the ice cream has the advantage of circulating less than 10 volumes than when using brine.

According to the invention, the refrigerant in the form of brine or soap is to operate in the temperature range of -2 to -20 ° C. The temperature of the refrigerant is preferably between -4 and -12 ° C, e.g. at -5 ° C. In the mentioned intervals, energy consumption is small and a satisfactory process time is obtained.

Preferably, the rate of relative movement between the refrigerant and carcass parts is between 0.02 and 1 m / s, preferably between 0.05 and 0.2 m / s. By such forced convection about the carcass portion, sufficient heat transfer is obtained to allow the portion to cool rapidly.

The relative motion is preferably provided by passing carcass parts hanging in a suspension conveyor through a vessel containing the refrigerant.

20 The carcass parts are individually wrapped in a foil before being immersed in the refrigerant. The refrigerant and carcass parts are thereby kept apart from each other during the cooling process by means of the foil which prevents the body parts from exchanging substances with the refrigerant. When the carcass parts are wrapped in separate foil, cross-contamination between the individual body parts is avoided. Furthermore, the body parts do not lose weight when wrapped in a foil.

25 Plastic, textile or rubber films or films up to 1 mm thick can be used. Plastics and textiles have heat conductive properties that are largely similar to carcass parts. Det DK 173153 B1 5 means that in the thermophysical context, the wrap only increases the body parts with the film thickness, provided the film sits close to the surface. A polyethylene foil having a thickness of 0.15 mm has been found to have sufficient strength and flexibility to be able to stretch over body parts with protruding legs, e.g. half pig carcass with cut off head.

5 Polyethylene is the most widely used material for packaging meat and meat products.

To avoid or reduce the presence of air between the foil and the carcass body surface, the air is preferably sucked out of the carcass body part. Pipes can be used for this to contact the places where air pockets are frequent. The air is sucked out until the foil sits close to the body part over as large an area as possible.

10 The casing can be closed tightly before the cooling begins by immersing the shrouded body part in the refrigerant.

The foil encloses the carcass while it is in the cooling bath. The refrigerant presses the foil against the carcass, thereby ensuring an efficient heat transfer from body part to refrigerant.

15 On the slaughter lines of pig slaughterers, half the carcasses are hung in pairs suspended in hinges.

During such half-carcass wrapping and transport of the bodies through the cooling bath, the half-carcasses may remain on the hinge so that identification is preserved.

The carcass parts can be immersed in the refrigerant by means of e.g. a vertical standing cylinder which lowers the hinge or a fixture with the hinge so far down that the carcass parts 20 are immersed in the cooling bath. The cooling bath may be designed as a large vessel in which the carcass parts are passed around in a predetermined path by means of e.g. a chain conveyor having a long chain of fixed spacing between the hinges or fixtures thereof.

After cooling, the carcass parts are taken out of the cooling bath, e.g. using another cylinder. By applying a slight excess pressure within the envelope, the foil will release the carcass portion and can be removed. The half-carcass hinge can then be transferred to the slaughterhouse's usual guide rod or conveyor conveyor and passed on to an equalization cooling room to compensate for temperature differences.

DK 173153 B1 6

As a solid in the brine or ice cream, a salt such as NaCl may be used. An alcohol or glycol can be used as an organic liquid. By changing the amount or type of additive, the working temperature of the brine or the scoop can be adjusted so that no substantial freezing in the brine or substantial thickening of the scoop at this temperature occurs.

Preferably, as cooling medium, soap is based on an aqueous NaCl solution or a mixture of water and ethanol.

An aqueous NaCl solution has good thermal properties (slightly inferior to water), but due to corrosion, the use places the environment in which the refrigerant must be used. 20% NaCl solution is frost proof to -15 ° C.

An aqueous solution of other salts may be used, e.g. a potassium acetate solution which has slightly poorer thermal properties but is attractive as a cooling medium due to the low freezing point and non-toxicity of the solution.

An aqueous calcium chloride solution with 17% by weight calcium chloride is frost-proof to -15 ° C. The solution is corrosive. A non-corrosive solution of this type is sold under the name Coolant, A calcium chloride solution is very inexpensive and suitable for use with foodstuffs. The heat capacity is 5-10% inferior to that of NaCl solutions.

A frost-proof potassium acetate solution can e.g. is manufactured using the commercial product Aspen Temper -20. The solution has good thermophysical properties and can, according to the manufacturer's statements, be used with food.

A mixture of propylene glycol and water with 33% by weight of propylene glycol is frost-proofed to -15 ° C. The thermophysical properties of the solution are inferior to water, especially in terms of dynamic viscosity and volume specific heat capacity.

A mixture of ethanol and water with 25% by weight ethanol is frost-proof to -15 ° C. The thermophysical properties are inferior to water, but better than that of propylene glycol.

DK 173153 B1 7

The latent melt heat in ice-cream results in a higher heat transfer rate and lower volume flow than when using a brine. For ice-cream, heat transfer rates are measured, which are two to three times greater than in brines. The good heat-transfer rates for soap ice cream are obtained, in particular, by ice content over 15% by weight. The viscosity is higher than that of briner. The pressure loss in circulating 5 ice creams is steadily increasing with the content of ice cream until an ice cream content of approx. 30% by weight. However, the increased pressure loss compared to using brine must be seen in the light of the fact that the circulated amount is significantly reduced due to the utilization of the latent heat of the ice cream. The overall result is a diminished pump power requirement. Soap ice can be pumped with traditional centrifugal pumps.

Preferably, ice cream is used with an ice cream content of not more than 35% by weight, in particular 10-30% by weight.

The good heat-transfer rates for soap-ice can be used to reduce the process time.

According to one embodiment, the brine or scoop may contain NaCl.

According to another embodiment, the brine may contain 5-25% by weight of ethanol.

Advantageously, the brine or scoop ice can be cooled in a one-stage cooling system, which saves significant amounts of energy compared to two-stage cooling systems used in tunnel systems.

The process according to the invention is preferably carried out under such conditions as to provide an external heat transfer rate of between 150 and 2500 W / m2K, especially between 300 and 1000 W / m2K.

20 Upon cooling with shell freeze, the thermal properties of the frozen layer change, and a large amount of cold is stored in the frozen shell. Therefore, for the same equalized temperature, the cooling time is shorter than without shell freezing.

To avoid meat quality degradation, the carcass parts must be frozen pre-rigor to a given maximum depth.

DK 173153 Pg 8

After the carcass parts have delivered a heat quantity to the refrigerant that can correspond to the desired final temperature, they are taken up by the medium and then allowed to offset temperature differences.

In a particular embodiment, the carcass parts are cooled in the refrigerant after equalization (post-5 rigor) until the parts are frozen.

By pig carcass parts according to the invention is meant whole pig carcasses or half or quarter pig carcasses.

The system according to the invention for cooling slaughter heat pig carcass parts for cooling temperature is characterized in that it comprises a vessel, a device for lowering 10 carcass parts conveyed by a conveying line, into a refrigerant in the vessel, a conveyor for carrying the carcass parts around. the vessel in a predetermined path, a cooling system arranged to cool the refrigerant, a device for taking the carcass parts up to the refrigerant in the vessel, and a conveyor to send the parts to an equalization cooling room to compensate for temperature differences.

The invention is further explained in the following examples.

Example 1

Heat transfer rates for half pig carcasses

This example aims to investigate the importance of the coolant flow rate for the external heat transfer rate for half pig carcasses. The exterior heat-transfer rate has a significant effect on the cooling of the carcass as the process time increases with decreasing transition rates. Therefore, an essential prerequisite for being able to use new cooling methods for pig carcasses is that a heat transfer number sufficient to achieve an acceptable cooling time can be provided.

DK 173153 B1 9

However, studies according to the present example have shown that using a refrigerant with a temperature below 0 ° C is not only possible to obtain advantageous process times, but that it can also be done without special flow engineering measures. Brine or ice cream is used as a refrigerant with a temperature below 0 ° C.

Thus, by using brine or soap ice as a cooling medium, process times of less than 60 minutes and less can be obtained, e.g. 35-50 minutes, with a restrained forced convection, e.g. a flow rate of the refrigerant between 0.2 and 0.5 m / s.

A sufficiently high external heat transfer rate between the refrigerant and the carcass is an essential prerequisite for obtaining short cooling times. It depends on the cooling medium 10 and the flow profile, including the orientation of the pig relative to the flow.

The following heat transfer rates are calculated for half carcasses that are cooled in brine or forced-convection ice cream:

Flow rate Brine Soap ice (m / s) Heat transfer number 15 (W / m2K) 0.1 500 1050 0.2 800 1630 0.5 1660 3070 1.0 2900 5175 20 It is seen that with soap ice exterior heat transfer numbers, it's about. twice the size of brine, despite the fact that the soap ice has three times as high viscosity as brine. Thus, the disadvantage of a higher viscosity is more than offset by the high Prandl ratio and heat conductivity of the soap ice.

A conveyor line conveyor typically has a speed of approx. 0.05 m / s. If, at this rate, the carcasses are passed through the refrigerant in the form of brine or soap, a sufficient convective contribution is obtained to provide shortened cooling times.

DK 173153 Pg 10

When using ice-water mixtures as a cooling medium (ie with a temperature of 0 ° C), similar cooling times should be expected as for tunnel cooling of pig carcasses. Ice-water mixtures as a cooling medium for pig carcasses are therefore not an attractive alternative to tunnel cooling of pig carcasses. The thermal properties of meat pose the most significant restriction on energy transport when the heat transfer rate is greater than approx. 500 W / nVK.

Example 2 The importance of the refrigerant for the cooling rate

This example aims to investigate the influence of various parameters on the cooling of a dummy that illuminates a warm, half pig carcass. The dummy is heated to 35 ° C in a heating bath and cooled by immersion in a refrigerant in the form of brine or soap ice. The refrigerants are based on ethanol and water. The effect of the following parameters is investigated: The flow rate of the refrigerant relative to the drip, the temperature of the refrigerant and the ice fraction in the ice cream.

0.05 m / s is chosen as the low flow rate level. This corresponds to the chain speed of 15 existing tunnel conveyors at a slaughter rate of 600 pigs / hour. As a high level, a flow rate of 0.12 m / s is chosen. The cooling process here is primarily determined by the thermal properties of the dummy (carcass), since the heat transfer rate is greater than 500 W / m2K.

The effect of the refrigerant temperature is investigated at a high and a low level. The low level of 20 -8 ° C is determined in order to obtain a final shell freeze. The high level is chosen to avoid shell freezing, which starts at approx. + 2 ° C. However, it is necessary to take into account what is possible with soapy ice, and as a compromise is therefore chosen -4 ° C as high level.

Three levels of chunks are used. The Gibbs phase rule sets two degrees of freedom in the equilibrium state of the ice 25. Thus, it is not possible to freely specify the temperature and ice content at a given ethanol concentration. At the low level the proportion is 0% by weight (= brine). There is used a mixture of 25% by weight ethanol (antifreeze to -15 ° C). As the middle level, 15% by weight of ice cream is selected. At the high level, the ice fraction is 25% by weight, as higher ice proportions cause a drastic increase in viscosity and there is a risk of ice clumping.

The following ethanol concentrations are used which allow the desired combinations of temperature and ice fraction:

Temperature (° C) Part of ice (%) Ethanol (%) -3.8 15 7 -4.2 25 7 10 -8.0 25 12 -8.2 15 14

The dummy is cooled in a refrigerator containing brine or ice-cream which is circulated in an outer cooling circuit. The volume flow to the cooling vessel is measured and the inlet valve or pump speed is set so that the volume flow corresponds to the desired flow rate.

The heat output of the dummy to the refrigerant is recorded by means of thermal sensors in the dummy. The obtained measurement results are subjected to statistical analysis to determine the effect of a change of the parameters on the mean heat flux of the dummy (mean heat flux is defined by the ratio of the removed amount of energy to the process time in the refrigerator). Main effects 20 and interactions are investigated by multi-variance analysis.

1. Flow rate

The statistical analysis shows that a change in flow rate has no significant effect on the cooling process when the flow rate ranges from 0.05 m / s to 0.12 m / s. Thus, the cooling vessel can be designed relatively simply, and there is no need for 25 special arrangements to provide high flow rates.

DK 173153 B1 12 2. Isandel

At a temperature of the refrigerant of -8 ° C, the analysis shows that the ice fraction only affects the cooling process at an ice fraction of between 0 and 15% by weight. The average mean flux is 292 W / m2 at 0 wt% ice fraction, while it is 337 W / m2 at 15 wt% ice fraction. If the ice cream content in the ice cream is increased from 15 to 25% by weight no appreciable change is achieved. The results show that some degree of shell freezing occurs. A certain portion of ice increases the heat transfer rate, but this ratio does not change significantly in the range between 15 and 25% by weight of ice. Thus, when using ice cream with between 15 and 25% by weight of ice, it is possible to reduce the processing time by approx. 15% compared to 10 using a corresponding ethanol-based brine (0% ice fraction).

At a temperature of the refrigerant of -4 ° C there is no noticeable effect of changing the ice fraction.

The same cooling time is available. This may be due to the fact that shell freezing does not occur to a significant extent. An improvement of the heat transfer rate beyond 500W / m2K does not noticeably reduce the cooling time, as the thermal resistance of the dummy to heat transport becomes the dominant factor.

3. Temperature

The analysis shows that the temperature of the refrigerant has a significant effect on the cooling process.

By reducing the temperature from -4 ° C to -8 ° C, the mean flux is increased by approx. 20% for both ice-cream and brine. It is likely that a further reduction of the cooling time can be achieved by lowering the temperature of the refrigerant even further, but at the same time the shell freezing is increased so that there is a risk of meat quality deterioration. In addition, energy consumption is rising.

For a typical screw compressor, energy consumption will increase 10-12% as the suction pressure is lowered from -15 ° C to -18 ° C. Furthermore, plant costs will increase because the compressor capacity is reduced.

DK 173153 Pg 13 4. Process time

The study shows that with brine or soap of -4 ° C, cooling times of approx. 70 minutes for pig carcasses of 74 kg. For brine of -8 ° C, a process time of approx. 60 minutes. Ice-cream of -8 ° C with an ice fraction of between 15 and 25% by weight 5 gives the fastest cooling process. The process time can be expected to be approx. 50 minutes.

Thus, cooling half carcases by means of a refrigerant in the form of brine or soap ice provides attractive process times at a temperature of the refrigerant in the range between -4 and -12 ° C.

Example 3 10 Comparison with traditional tunnel cooling

This example serves to compare the present refrigeration in a refrigerant in the form of brine or soap ice with conventional tunnel cooling of half pig carcasses.

It is assumed that these are 75 kg heavy pig carcasses that are fed on a slaughter line with a slaughter capacity of 600 pigs / hour. The cold demand is thus 1700 kW.

15 1. Tunnel cooling

The tunnel cooling system used for traditional tunnel cooling with air as a cooling medium comprises a two stage ammonia cooling system. The low pressure plant consists of tunnel evaporators, screw compressors, piston compressors, a low pressure separator, pipes and valves. The compressors have a capacity of 1700 kW at -35 ° C / -10 ° C. The high-pressure system consists of 20 screw compressors, piston compressors, an intermediate cooler, capacitors, recipient, pipes and valves. The high-pressure side compressor capacity is 2200 kW at -10 ° C / 35 ° C. The area of the evaporator varies according to the location in the tunnel, ie. that there is less but more evaporators at the beginning of the process, whereas the evaporator area has doubled at the end of the tunnel, while the number of evaporators has been reduced accordingly.

DK 173153 B1 14

The half pig carcasses are cooled from the heat of slaughter to 7 ° C in 70 minutes. The cooling loss is 0.8% of the carcass weight. The required area for cooling tunnel is approx. 0.7 m2 / pig. The plant has a high electricity consumption for the operation of compressors and fans in the tunnel.

2. Cooling with brine 5 The cooling system used for cooling half carcases by brine comprises a one-stage ammonia cooling system, built of a plate heat exchanger, screw compressors, piston compressors, liquid separator, capacitors, recipient, pipes and valves. The total cooling capacity of the compressors is 1700 kW at -15 ° C / 35 ° C.

The brine consists of a mixture of 25 wt.% Ethanol and 75 wt.% Water which holds 10 in a refrigerator. The temperature of the brine is maintained at -8 ° C by means of the cooling system. After wrapping the half carcasses in a foil, they are immersed in the refrigerator that holds 700 m3 of brine. In the refrigeration system, approx. 5 m3 brine.

Measurements show that it is unnecessary to use pump energy to create circulation of brine in the tub. The pumps of the system must only supply cold brine to the vessel corresponding to the cold requirement.

Heating the brine in the vessel is assumed to be 2 ° C. The pumps circulate 720 m3 of brine per year. hour. Pressure loss in the system is estimated to be a maximum of approx. 300 kPa (30 mVS). Two pumps with a total power consumption of approx. 90 kW.

The brine is cooled in the cooling system from -6 to -10 ° C. In a mixing loop, half the amount of return brine is circulated, ie. 360 mVtime. The pressure drop in mixing loop and plate heat exchanger is set to approx. 150 20 kPa (15mVs). A pump with a power consumption of approx. 25 kW.

The carcasses are cooled to 7 ° C in 59 minutes. The shrinkage is 0%. The area requirement is only 0.4 to 0.5 m2 / pig carcass, since cooling takes place faster than with tunnel cooling. The one-stage system requires only half the space in the machine center.

DK 173153 B1 15 3. Cooling with ice-cream The cooling system used for cooling half-carcasses by means of ice-cream comprises a one-stage ammonia cooling system, built of a ice-cream generator, a ice-cream container, skimming compressors, piston compressors, liquid separator, capacitors, recipient, pipes and 5 valves. The total cooling capacity of the compressors is 850 kW at the operating point -15 eC / 35 ° C. The ice cream is produced on a soap ice generator with a capacity of 850 kW.

The ice cream is made from 12% by weight ethanol and 88% by weight water. The ice cream is brought to a refrigerator that holds 700 m3 of ice cream. In the ice-cooler system and buffer tank, approx. 10 m3 of ice-cream.

10 For the production of ice cream, a generator with mechanical agitation is used to avoid freezing of ice particles on the wall between primary and secondary refrigerant. For stirring in the generator, approx. 10% of the cooling effect.

Due to the large cold capacity, which is in the proportion of ice cream, a large part of the cold demand can be produced and accumulated during the electricity plant's low tariff period. The accumulated 15 liters of cold is used per day during the operating period. The ice cream should be stirred during storage. The energy used for stirring by means of propellers is about 1 percent of the cooling power, ie. ca. 20 kW.

The ice cream is charged to the refrigerator with 25% by weight ice and removed by 15% by weight; thus, 130 m3 of ice-cream per cycle must be circulated. hour.

20 Soap ice with 25% by weight ice cream is more viscous than a brine, and the pressure drop in tubes is typically 3-4 times greater at the same flow rate. With a flow rate of 0.5 m / s or less, the same system pressure loss as for the brine can be calculated.

The carcasses are cooled to 7 ° C in 49 minutes. The shrinkage is 0%. The one-stage system requires only half the space in the machine center.

DK 173153 Bl 16 4. Calculations

Based on the above assumptions, calculations show that investments for the brine and soap ice cold plants are approx. 30% lower than the tunnel cooling system.

Operating costs are only approx. 1/4 of the cost of operating the tunnel cooling system.

5 Electricity costs constitute a significant part of operating costs. They are reduced to one-half at the railway system and one-third at the soap-ice plant.

Brine cooling reduces the processing time from 70 to 59 minutes. In case of ice-cold cooling, the process time is reduced to 49 minutes.

At the brine and soap ice plants, the shrinkage is 0%, as the body is prevented from releasing moisture due to the wrapping in foil 10.

The analysis thus shows that, compared to the tunnel cooling used today, very significant electricity savings have been achieved, a reduction in process time and a reduction in weight loss.

Using ice-cream as a refrigerant is economically more attractive than brine cooling.

Example 4 15 Ice-ice compositions

This example indicates suitable compositions of ice cream.

The ice cream used in the process according to the invention is conveniently based on a compromise between the ice proportion and the viscosity at the working temperature. At a working temperature of between -4 and -6 ° C, relatively weak concentrations of the freezing point reducing agent, e.g. 2-15% by weight ethanol, propylene glycol or NaCl.

DK 173153 B1 17 Measured properties of various ice cream mixes are shown in the table below.

Addition- Weight% Starting temp. * 'For Temp. V. Ice fraction' 'substance icing (eC) (° C) (%) 5 NaCl 2 6 -4.5 1.2 40

Ethanol 3 -1.2 0.5 40 6 -2.5 0.5 40 10 10 -4.2 0.6 40

Propylene Glycol 6 -1.6 0.4 40 10 -2.6 0.5 35 15 -4.1 0.9 35 15 Children: *) ± 0.5 ° C; **) ± 10%

The temperature change in the phase conversion of ice to water is the same for all three types.

At a given desired freezing point, NaCl provides the most aqueous mixture.

Calculated values for density, dynamic viscosity and heat conductivity for freezing point mixtures in the range of -4 to -5 ° C show that NaCI based ice cream has the best 20 thermophysical properties of the three.

The energy content per kg of ice cream is a direct function of the ice cream content. For the sake of dynamic viscosity, it is most convenient to use ice cream with an ice content of less than 35% by weight, especially below 30% by weight.

Claims (12)

Method for cooling the slaughter heat pig carcass parts for cooling temperature, characterized in that the carcass parts are individually wrapped in a foil, that the enclosed carcass parts are immersed in a refrigerant in the form of brine or soap with a temperature of between 2 and 2. 20 ° C, providing relative movement between the refrigerant and the carcass portions, keeping the carcass portions in the refrigerant until they are frozen, and delivering a heat amount to the refrigerant substantially similar to cooling the carcass portions from the carcass to cool temperature, the carcass portions being taken up, that the film is then removed and that the carcass parts are finally allowed to offset temperature differences. Process according to claim 1, characterized in that the temperature of the refrigerant is between -4 and -12 ° C. Method according to claim 1, characterized in that the speed of the relative movement between the refrigerant and the carcass parts is between 0.02 and 1 m / s. Method according to claim 1, characterized in that the relative motion is provided by passing carcass parts hanging in a hanging conveyor through a vessel containing the refrigerant. Process according to claim 1, characterized in that soap is used with an ice cream content of not more than 35% by weight, in particular 10-30% by weight. Process according to Claim 1, characterized in that the brine or ice cream contains NaCl. Process according to claim 1, characterized in that the brine or ice cream contains 5-25% by weight ethanol. Process according to claim 1, characterized in that the brine or ice-cream is cooled in a one-stage cooling system. DK 173153 B1 Method according to claim 1, characterized in that it is carried out under such conditions that an external heat transfer number for the carcass parts of between 150 and 2500 W / nrK is provided, preferably between 300 and 1000 W / nrK. Method according to claim 1, characterized in that the carcass parts must be frozen prior to rig 5 at a given maximum depth. Process according to claim 1, characterized in that the cooling of the carcass parts in the refrigerant is continued after equalization (post-rigor) until the parts are frozen. 12. Cooling system for cooling pork carcass parts for cooling temperature, characterized in that it comprises a vessel, a device for lowering carcass parts conveyed by a conveying line, into a refrigerant in the vessel, a conveyor for passing the carcass parts around the vessel. in a predetermined path, a refrigeration system adapted to cool the refrigerant, a device for taking the carcass parts up to the refrigerant in the tub, and a conveyor for sending the parts to an equalization cooling room to compensate for temperature differences.