The refrigeration equipment includes a gas compressor driven by an electric motor, a heat exchanger with a zigzag-shaped pipe called a condenser "Condenser (thermodynamics)"), another with a coil-shaped pipe called an evaporator and an expansion valve, all interconnected by copper pipes forming a closed circuit. The refrigerant gas is introduced inside the pipe through a valve. The compressor and condenser are outside the cold room while the expansion valve and evaporator are inside the room, usually on the entrance door frame. As the compressor works, it raises the pressure of the gas that arrives hot from the chamber due to the calories it took from the stored products. When the gas reaches the expected pressure and temperature values, it is up to the gas to pass through the condenser to the liquid phase, emitting latent heat of fusion. The condenser is provided with fins that transmit the heat that passes through the walls of the pipe to the air. If necessary, a closed-circuit rainwater system is installed to help dissipate heat. The length of the coil is calculated so that the liquefied gas leaves the condenser at room temperature. It then passes through the expansion valve, already inside the chamber, and loses pressure. When it reaches the evaporator the gas is cold and without pressure. It is up to you to return to your gaseous state. It requires latent heat of evaporation. This takes it from the copper pipe, which is therefore cooled and this in turn takes heat from the air. With the help of a fan, a current of hot air is established from the chamber that passes through the evaporator coil, delivering calories from the air and the stored products. The gas arrives hot at the compressor, completing the circuit. The process continues to cool the air and stored products until the temperature reaches +/-1°C lower than set. A thermostat closes the expansion valve and a pressure switch closes the compressor flow. After a while the temperature rises due to the heat passing through the walls and the opening of the chamber door. When it reaches +/-1 °C higher than the set value, the valve opens and the current flows. The cycle works again.

Since the end of the century, ammonia has been used as a refrigerant gas, but it is toxic and therefore dangerous when there are gas leaks. In the 70s of the century it was replaced by gas from the chloro-fluorine-carbon CFC family called commercially Freon or R11. A few years ago it was discovered that these gases are the main cause of the hole in the ozone layer, and since then a replacement has been sought that has the same characteristics as Freon but that decomposes before reaching the ozone layer. One of the alternatives that has curiously gained more strength is CO2 and is part of a patent by Alexander Twining from 1850. Its use until 1940 was common but declined in favor of the aforementioned gases. As a consequence of the observation of the ozone hole, the international community once again considered its use and after trials, optimal concentration doses and working regimes were proposed that have made this system a clear commercial alternative.

In the meantime, gases from the same family continue to be used but are less harmful. In large facilities with monitoring personnel, ammonia, also called R717, is still used.

As historical data, we can add that the demand for cold rooms for industry and individuals skyrocketed after the Second World War Archived on March 11, 2021 at the Wayback Machine, due to the important need to maintain food in optimal conditions.

The plant building has a floor, walls and ceiling covered with several layers of insulating plastic material and between them a metal sheet to prevent the infiltration of humidity (water vapor).

The building includes:

Refrigerating is a capital-intensive activity. The investment service in building, insulation, facilities and machinery amounts to 50% of the expenses. Other fixed expenses (maintenance and security personnel, taxes) add up to 15%. Variable expenses are only 35%. The investor must ensure the occupancy of the rooms.

There are advantages of scale: costs per cubic meter of cold room decrease with the size of the facilities.

Contenido

Para sacar el mayor provecho del almacenamiento en el frigorífico de frutas y hortalizas, hay que realizar correctamente operaciones previas en la cosecha y post cosecha, a saber:.

Harvest

The fruit must be harvested at the beginning of the ripening period so that, after cooling, it has the time necessary for packaging and the marketing stages and reaches the consumer days before complete ripening.

During harvest, the fruit must be prevented from receiving blows. On large farms, the harvester places the fruit in a cloth bag attached to his waist. When it is full, it dumps the contents into crates, located between the rows of trees, which can contain 300-400 kg of fruit. It is also possible for the harvester to deposit the fruit unit by unit into the drawers, thus avoiding irreversible impacts often caused by the bags.

The drawers, which in the past were made of wood and now generally made of plastic, are of different sizes. One model is 1.60 x 1.05 m and 0.60 m high and another is 1.12 x 1.12 m and 0.80 m high, and they have legs that fit into the upper frame of a lower drawer, forming pallets. A tractor, which has an application mounted on the hydraulic power take-off that transforms it into a lifting forklift, transports it to a truck and the latter to the covered patio of the meat processing plant. On small farms the harvester carries a 20 kg plastic box. When it is filled, it is taken to a roof forming pallets and a truck transports them to the refrigerator. Damage to the tissues due to blows or falls is not noticeable at the time, but the damaged tissue is attacked by bacteria and rots shortly afterwards, which damages the fruits that are nearby. In other cases, spots appear on the skin.

Parameters

Four parameters determine the behavior of the fruit in the refrigerator: Temperature, relative humidity, storage time and whether it is climatic or not. Tables are given with values ​​of temperature and relative humidity that should prevail in the room and the time that it is possible to keep fruits and vegetables. The values ​​are approximate, since they vary with the variety and the climate of the region.

Temperature

It can be indicated in general terms that fruits and vegetables from a temperate climate should be kept between 0 °C and 4 °C and those from a subtropical and tropical climate from 8 °C to 13 °C. When fruits are stored at different temperatures, they will have to be cooled to the highest temperature due to the danger of spoilage. Tropical fruits and vegetables do not extend their shelf life by lowering the temperature. They have the advantage of a long harvest period.

Relative humidity

The vast majority require 95-98% humidity. If the humidity in the chamber is less than what it corresponds to, the air takes moisture from the stored fruit and when it leaves it weighs less than when it entered and there is a danger that the skin will wrinkle. If it reaches 100% there is a danger that some of the humidity will freeze as it passes through the evaporator.

Time

Those that respond best to cooling are apples and pears (4-5 months), carrots, onions and garlic (4-6 months), potatoes and sweet potatoes until harvest the following year. Mango, avocado and banana for export are harvested green and ripen until they reach their destination. The banana that arrives at its green destination is ripened in quarters with ethylene.

Ethylene

Ethylene is a hydrocarbon (CH) that a hormone exhales suddenly in certain fruits at the beginning of ripening and influences accelerating it and giving particular characteristics of color and texture. These fruits are called climatic. The main ones are:

The non-climatic ones (which do not produce ethylene or very little) are: grapes, olives, citrus fruits, lich, pineapple, strawberries, cherries and vegetables. This determines that different climatic fruits cannot ripen in the same chamber since there is an increase in the amount of ethylene that excessively speeds up ripening and forces fruit to be removed before the scheduled time. The apple rooms have not only separate rooms but separate entrances from the outside with the kiwi.

Controlled air cold rooms (Controlled Atmosphere)

By reducing the proportion of oxygen in the air in the chamber, the respiration rate of the fruit decreases and this allows the time that the fruit remains in the refrigerator to be prolonged. One of the methods is to reduce oxygen to 1%, replacing the missing amount with nitrogen (inert gas) and keeping the percentage of CO constant. Specialized firms sell appropriate equipment that changes the composition of the chamber atmosphere and ensures that it does not vary throughout the entire time until opening. In this way, the sale of apples and pears can be maintained until the following year's harvest. In the publications consulted there is reference to different formulas and equipment that are applied to other fruits with the aim of exporting off-season in containers with treated air, by ship, or in refrigerators.

Marketing planning

Producers who send their production to the refrigerator have to plan their marketing policy having 3 alternatives to choose from:

According to the varieties you have, you can use the 3 channels in different proportions according to the characteristics of the varieties you have and those of the market: A producer of 5 varieties can decide for their production of the Orleans variety to send 50% directly to the market, 25 to common cold rooms and another 25% to Controlled Environment while for the Johnatan variety to send 10% to the market, 30 to common and 60% to controlled. The other varieties have intermediate proportions. The cost of cooling in AC is double but the increase in cost is marginal taking into account the increase in production achieved.

Fast cooling

As the temperature drops, the activity of the bacteria decreases and so does the respiration rate, which is why it is important to reach +/- 10 °C in the shortest time. In the case of pears and apples, it is allowed to arrive within 24 hours but in many cases it is necessary to arrive faster. For this there are several possibilities, namely:

The flowers are cut from the stem of the bush, placed in buckets with cold water and taken to the farm's refrigerator. If the farm is large, they are classified by variety, color and stem length. They are placed in cardboard boxes according to orders and sent cooled with 100% humidity, in a refrigerated truck, to clients or the Central Flower Market. The temperature should be a few degrees above 0 °C. If the farm is small, a truck picks up the buckets and transports them to the regional packaging center. An inspector controls the quality, receives the good ones and gives a receipt for variety and quantity.

La carne es uno de los componentes principales de la alimentación humana. Se consume de diferentes tipos de animales. Los principales son: vacunos, porcinos y aves de corral y en menor cantidad de ovinos, caprinos y conejos. Para poder ser consumidos deben pasar primero por el matadero donde se realizan diferentes etapas para obtener la carne y otros componentes.

Cool beef

The process of slaughtering cattle includes: stunning and bleeding through the jugular vein (blood is collected). The animal hangs by its hind legs from a track mounted on a rail. The following operations are: skinning of the skin (it is sent to the salting plant for temporary conservation), cutting of the legs, cutting of the head (it goes to the secondary processing line), extraction of the thoracic and abdominal viscera (those intended for human or industrial consumption go to the lateral processing line), cutting of the carcass&action=edit&redlink=1 "Carcass (meat industry) (not yet written)") along the spine and finally washing.

During the entire process, even with ventilation and air cooling, the temperature of the half carcass is 35-38 °C and although the meat of the live animal is aseptic, the contact of the staff and their tools with the carcass brings bacteria that develop rapidly at that temperature. Under these conditions, the meat has a shelf life of 1-2 days, insufficient to reach the consumer. It is essential to lower the temperature, and for this reason the slaughterhouse must include cold rooms to lower the temperature to 4 °C (7 °C inside the thickest section). The number of rooms is a function of the refrigerator's work rate, taking into account that the process lasts from 24 to 36 hours depending on the size of the half carcasses and that the first one to enter the room should not wait more than half an hour until the cooling begins. A continuous process can be established with a tunnel with a stainless steel fabric conveyor belt where the half carcasses are deposited, which receive countercurrent cold air at a temperature of 4-5 °C. In these conditions the useful life is a maximum of 3-5 weeks. The slaughterhouse can then establish a distribution center with a stock of 2-3 weeks of production to supply wholesalers in neighboring cities and supermarkets, respecting that deliveries are FIFO (first in, first out).

Freeze

When meat is destined for export or it is necessary to store surplus production for a period longer than 3-5 weeks, it is necessary to freeze the meat at -30 °C. At these temperatures, cold-resistant bacteria die and the lifespan is 1 year or more. The freezing room receives meat at 5 °C and the refrigeration equipment sends strong air currents between -30 and -40 °C. If the current is strong enough, the change of state of the water between the tissues changes state, forming small crystals. If the change is slow, in the period of change of state the water gathers in droplets that form large crystals that break fibers of the muscle tissues and change the structure and taste of the meat. Prefabricated chambers and tunnels are offered on the market, each with the necessary equipment to freeze at various temperatures, with air speed of up to 6 m/sec and RH 95%. The freezing process lasts between 12 and 18 hours for half a carcass. The frozen meat is wrapped with a layer of cotton fabric and another layer of plastic with instructions. The cost of frozen is much higher than chilled.

Bone

An alternative process is to transfer the half carcass from the slaughterhouse to a refrigerated room to debone and separate cuts in the half carcass, arranging the prime cuts in one cardboard box and the cuts for the "industry" (preparation of cold cuts, sausages, hamburgers, canned products) in another. The boxes are placed in a plate freezer that freezes at -30 °C. In this way the weight is reduced by 30 and the volume by 50%. The bones go to the digester to produce bone meal.

In plate freezers, they act as evaporators, taking calories from the products that were placed between the layers. When the equipment operates, the plates press the boxes for better heat transmission.

IQF

Individual Quick Freezing is a freezing process that is carried out on previously cooled cuts of meat. The cuts (not thick) are deposited in tunnels with stainless steel tape, which receive strong air currents that lower the temperature of the cuts to -20 or -30 °C. A control panel allows the speed of the belt to be varied. When they leave the tunnel they go to the packaging, which wraps the cut in a special plastic bag that does not allow gases to pass through. The open end is connected to a vacuum bag and sealed. The development of these systems is based on the use of domestic freezers where it is possible to keep products at -18 °C (0 °F) and thus have a reserve of meat at home.

El pescado es más sensible que la carne al ataque de bacterias. Enfriado a temperaturas cercanas a 0 °C tiene una vida útil de pocos días. Como ejemplo: bacalao y salmón 3 días, camarón 2, atún y arenque 1. No queda tiempo para el mercadeo. El procedimiento normal es congelar a -20 °C o más bajo.

Los barcos pesqueros de alta mar están provistos de cuartos frigoríficos donde mantienen la pesca cercana a los 0 °C, o en su defecto en cajas con hielo en escamas o en piletas con agua de mar enfriada a cerca de 0 °C. Los barcos-factorías tienen también cuartos para congelar. De vuelta a la costa, se envía la pesca a la planta de procesamiento más cercana. Si es de peces medianos o chicos, por un caño con corriente de agua de mar, y si son grandes con montacargas. La primera etapa en la planta es la limpieza, que se hace de forma manual o mecánica de acuerdo al precio de la mano de obra y el tipo de pescado. Las operaciones incluyen:.

Para algunas operaciones hay diferentes modelos de acuerdo a la variedad y al tamaño del pescado a procesar.

Frozen

It is carried out in cold rooms with strong air currents at -30 to -40 °C. Large fish such as tuna and cod are hung on rails that run on a rail similar to that of half-carcasses. Fans on the wall perpendicular to the track send strong air currents. The smaller fish are placed in trays that are placed on carts that roll into the room, and on top of them there is an evaporator. A fan attached to the evaporator sends a current to the carts and another at the opposite end absorbs the air that passed through the carts. In this way, a closed circuit is generated that lowers the temperature until it reaches the set temperature. The carts are removed from the room, the trays are removed and another load of fish is placed on trays. If possible, a train of carts is established so that the cart with the frozen load is removed from one end of the room and another loaded with fish to be frozen is introduced at the other end.

Fish or fillets are placed in a freezing tunnel with a stainless steel mesh and fall frozen to the other end by a current of air at a set temperature. An important factor in determining freezing time is thickness. The speed of the air does not have much influence on the speed of the temperature drop depending on the thickness of the fish. The tunnel control panel allows you to vary the different parameters (belt speed, air speed).

Vacuum packed

Home freezers are programmed to maintain a temperature of -18°C (0°F), sufficient for purchasing vacuum-packed frozen fish and fillets. When they leave the belt or the freezing room, they are bagged in gas-impermeable plastic. The bag is vacuumed and sealed.

Pecan is the nut that needs to be kept in the refrigerator at -2 to -4 °C and relative humidity of 60-70%. Before storing, the dry skin of the fruit must be removed. Generally the refrigerator is part of the plant that includes selection, classification, nut splitting and packaging. The other varieties do not require a refrigerator.

Generally the eggs are stored from the period of maximum production until the period of low production. The room temperature should be -1°C and RH 82 to 85%. Eggs absorb odors, so it is recommended to keep them in separate rooms.

The refrigeration equipment includes a gas compressor driven by an electric motor, a heat exchanger with a zigzag-shaped pipe called a condenser "Condenser (thermodynamics)"), another with a coil-shaped pipe called an evaporator and an expansion valve, all interconnected by copper pipes forming a closed circuit. The refrigerant gas is introduced inside the pipe through a valve. The compressor and condenser are outside the cold room while the expansion valve and evaporator are inside the room, usually on the entrance door frame. As the compressor works, it raises the pressure of the gas that arrives hot from the chamber due to the calories it took from the stored products. When the gas reaches the expected pressure and temperature values, it is up to the gas to pass through the condenser to the liquid phase, emitting latent heat of fusion. The condenser is provided with fins that transmit the heat that passes through the walls of the pipe to the air. If necessary, a closed-circuit rainwater system is installed to help dissipate heat. The length of the coil is calculated so that the liquefied gas leaves the condenser at room temperature. It then passes through the expansion valve, already inside the chamber, and loses pressure. When it reaches the evaporator the gas is cold and without pressure. It is up to you to return to your gaseous state. It requires latent heat of evaporation. This takes it from the copper pipe, which is therefore cooled and this in turn takes heat from the air. With the help of a fan, a current of hot air is established from the chamber that passes through the evaporator coil, delivering calories from the air and the stored products. The gas arrives hot at the compressor, completing the circuit. The process continues to cool the air and stored products until the temperature reaches +/-1°C lower than set. A thermostat closes the expansion valve and a pressure switch closes the compressor flow. After a while the temperature rises due to the heat passing through the walls and the opening of the chamber door. When it reaches +/-1 °C higher than the set value, the valve opens and the current flows. The cycle works again.

Since the end of the century, ammonia has been used as a refrigerant gas, but it is toxic and therefore dangerous when there are gas leaks. In the 70s of the century it was replaced by gas from the chloro-fluorine-carbon CFC family called commercially Freon or R11. A few years ago it was discovered that these gases are the main cause of the hole in the ozone layer, and since then a replacement has been sought that has the same characteristics as Freon but that decomposes before reaching the ozone layer. One of the alternatives that has curiously gained more strength is CO2 and is part of a patent by Alexander Twining from 1850. Its use until 1940 was common but declined in favor of the aforementioned gases. As a consequence of the observation of the ozone hole, the international community once again considered its use and after trials, optimal concentration doses and working regimes were proposed that have made this system a clear commercial alternative.

In the meantime, gases from the same family continue to be used but are less harmful. In large facilities with monitoring personnel, ammonia, also called R717, is still used.

As historical data, we can add that the demand for cold rooms for industry and individuals skyrocketed after the Second World War Archived on March 11, 2021 at the Wayback Machine, due to the important need to maintain food in optimal conditions.

The plant building has a floor, walls and ceiling covered with several layers of insulating plastic material and between them a metal sheet to prevent the infiltration of humidity (water vapor).

The building includes:

Refrigerating is a capital-intensive activity. The investment service in building, insulation, facilities and machinery amounts to 50% of the expenses. Other fixed expenses (maintenance and security personnel, taxes) add up to 15%. Variable expenses are only 35%. The investor must ensure the occupancy of the rooms.

There are advantages of scale: costs per cubic meter of cold room decrease with the size of the facilities.

Contenido

Para sacar el mayor provecho del almacenamiento en el frigorífico de frutas y hortalizas, hay que realizar correctamente operaciones previas en la cosecha y post cosecha, a saber:.

Harvest

The fruit must be harvested at the beginning of the ripening period so that, after cooling, it has the time necessary for packaging and the marketing stages and reaches the consumer days before complete ripening.

During harvest, the fruit must be prevented from receiving blows. On large farms, the harvester places the fruit in a cloth bag attached to his waist. When it is full, it dumps the contents into crates, located between the rows of trees, which can contain 300-400 kg of fruit. It is also possible for the harvester to deposit the fruit unit by unit into the drawers, thus avoiding irreversible impacts often caused by the bags.

The drawers, which in the past were made of wood and now generally made of plastic, are of different sizes. One model is 1.60 x 1.05 m and 0.60 m high and another is 1.12 x 1.12 m and 0.80 m high, and they have legs that fit into the upper frame of a lower drawer, forming pallets. A tractor, which has an application mounted on the hydraulic power take-off that transforms it into a lifting forklift, transports it to a truck and the latter to the covered patio of the meat processing plant. On small farms the harvester carries a 20 kg plastic box. When it is filled, it is taken to a roof forming pallets and a truck transports them to the refrigerator. Damage to the tissues due to blows or falls is not noticeable at the time, but the damaged tissue is attacked by bacteria and rots shortly afterwards, which damages the fruits that are nearby. In other cases, spots appear on the skin.

Parameters

Four parameters determine the behavior of the fruit in the refrigerator: Temperature, relative humidity, storage time and whether it is climatic or not. Tables are given with values ​​of temperature and relative humidity that should prevail in the room and the time that it is possible to keep fruits and vegetables. The values ​​are approximate, since they vary with the variety and the climate of the region.

Temperature

It can be indicated in general terms that fruits and vegetables from a temperate climate should be kept between 0 °C and 4 °C and those from a subtropical and tropical climate from 8 °C to 13 °C. When fruits are stored at different temperatures, they will have to be cooled to the highest temperature due to the danger of spoilage. Tropical fruits and vegetables do not extend their shelf life by lowering the temperature. They have the advantage of a long harvest period.

Relative humidity

The vast majority require 95-98% humidity. If the humidity in the chamber is less than what it corresponds to, the air takes moisture from the stored fruit and when it leaves it weighs less than when it entered and there is a danger that the skin will wrinkle. If it reaches 100% there is a danger that some of the humidity will freeze as it passes through the evaporator.

Time

Those that respond best to cooling are apples and pears (4-5 months), carrots, onions and garlic (4-6 months), potatoes and sweet potatoes until harvest the following year. Mango, avocado and banana for export are harvested green and ripen until they reach their destination. The banana that arrives at its green destination is ripened in quarters with ethylene.

Ethylene

Ethylene is a hydrocarbon (CH) that a hormone exhales suddenly in certain fruits at the beginning of ripening and influences accelerating it and giving particular characteristics of color and texture. These fruits are called climatic. The main ones are:

The non-climatic ones (which do not produce ethylene or very little) are: grapes, olives, citrus fruits, lich, pineapple, strawberries, cherries and vegetables. This determines that different climatic fruits cannot ripen in the same chamber since there is an increase in the amount of ethylene that excessively speeds up ripening and forces fruit to be removed before the scheduled time. The apple rooms have not only separate rooms but separate entrances from the outside with the kiwi.

Controlled air cold rooms (Controlled Atmosphere)

By reducing the proportion of oxygen in the air in the chamber, the respiration rate of the fruit decreases and this allows the time that the fruit remains in the refrigerator to be prolonged. One of the methods is to reduce oxygen to 1%, replacing the missing amount with nitrogen (inert gas) and keeping the percentage of CO constant. Specialized firms sell appropriate equipment that changes the composition of the chamber atmosphere and ensures that it does not vary throughout the entire time until opening. In this way, the sale of apples and pears can be maintained until the following year's harvest. In the publications consulted there is reference to different formulas and equipment that are applied to other fruits with the aim of exporting off-season in containers with treated air, by ship, or in refrigerators.

Marketing planning

Producers who send their production to the refrigerator have to plan their marketing policy having 3 alternatives to choose from:

According to the varieties you have, you can use the 3 channels in different proportions according to the characteristics of the varieties you have and those of the market: A producer of 5 varieties can decide for their production of the Orleans variety to send 50% directly to the market, 25 to common cold rooms and another 25% to Controlled Environment while for the Johnatan variety to send 10% to the market, 30 to common and 60% to controlled. The other varieties have intermediate proportions. The cost of cooling in AC is double but the increase in cost is marginal taking into account the increase in production achieved.

Fast cooling

As the temperature drops, the activity of the bacteria decreases and so does the respiration rate, which is why it is important to reach +/- 10 °C in the shortest time. In the case of pears and apples, it is allowed to arrive within 24 hours but in many cases it is necessary to arrive faster. For this there are several possibilities, namely:

The flowers are cut from the stem of the bush, placed in buckets with cold water and taken to the farm's refrigerator. If the farm is large, they are classified by variety, color and stem length. They are placed in cardboard boxes according to orders and sent cooled with 100% humidity, in a refrigerated truck, to clients or the Central Flower Market. The temperature should be a few degrees above 0 °C. If the farm is small, a truck picks up the buckets and transports them to the regional packaging center. An inspector controls the quality, receives the good ones and gives a receipt for variety and quantity.

La carne es uno de los componentes principales de la alimentación humana. Se consume de diferentes tipos de animales. Los principales son: vacunos, porcinos y aves de corral y en menor cantidad de ovinos, caprinos y conejos. Para poder ser consumidos deben pasar primero por el matadero donde se realizan diferentes etapas para obtener la carne y otros componentes.

Cool beef

The process of slaughtering cattle includes: stunning and bleeding through the jugular vein (blood is collected). The animal hangs by its hind legs from a track mounted on a rail. The following operations are: skinning of the skin (it is sent to the salting plant for temporary conservation), cutting of the legs, cutting of the head (it goes to the secondary processing line), extraction of the thoracic and abdominal viscera (those intended for human or industrial consumption go to the lateral processing line), cutting of the carcass&action=edit&redlink=1 "Carcass (meat industry) (not yet written)") along the spine and finally washing.

During the entire process, even with ventilation and air cooling, the temperature of the half carcass is 35-38 °C and although the meat of the live animal is aseptic, the contact of the staff and their tools with the carcass brings bacteria that develop rapidly at that temperature. Under these conditions, the meat has a shelf life of 1-2 days, insufficient to reach the consumer. It is essential to lower the temperature, and for this reason the slaughterhouse must include cold rooms to lower the temperature to 4 °C (7 °C inside the thickest section). The number of rooms is a function of the refrigerator's work rate, taking into account that the process lasts from 24 to 36 hours depending on the size of the half carcasses and that the first one to enter the room should not wait more than half an hour until the cooling begins. A continuous process can be established with a tunnel with a stainless steel fabric conveyor belt where the half carcasses are deposited, which receive countercurrent cold air at a temperature of 4-5 °C. In these conditions the useful life is a maximum of 3-5 weeks. The slaughterhouse can then establish a distribution center with a stock of 2-3 weeks of production to supply wholesalers in neighboring cities and supermarkets, respecting that deliveries are FIFO (first in, first out).

Freeze

When meat is destined for export or it is necessary to store surplus production for a period longer than 3-5 weeks, it is necessary to freeze the meat at -30 °C. At these temperatures, cold-resistant bacteria die and the lifespan is 1 year or more. The freezing room receives meat at 5 °C and the refrigeration equipment sends strong air currents between -30 and -40 °C. If the current is strong enough, the change of state of the water between the tissues changes state, forming small crystals. If the change is slow, in the period of change of state the water gathers in droplets that form large crystals that break fibers of the muscle tissues and change the structure and taste of the meat. Prefabricated chambers and tunnels are offered on the market, each with the necessary equipment to freeze at various temperatures, with air speed of up to 6 m/sec and RH 95%. The freezing process lasts between 12 and 18 hours for half a carcass. The frozen meat is wrapped with a layer of cotton fabric and another layer of plastic with instructions. The cost of frozen is much higher than chilled.

Bone

An alternative process is to transfer the half carcass from the slaughterhouse to a refrigerated room to debone and separate cuts in the half carcass, arranging the prime cuts in one cardboard box and the cuts for the "industry" (preparation of cold cuts, sausages, hamburgers, canned products) in another. The boxes are placed in a plate freezer that freezes at -30 °C. In this way the weight is reduced by 30 and the volume by 50%. The bones go to the digester to produce bone meal.

In plate freezers, they act as evaporators, taking calories from the products that were placed between the layers. When the equipment operates, the plates press the boxes for better heat transmission.

IQF

Individual Quick Freezing is a freezing process that is carried out on previously cooled cuts of meat. The cuts (not thick) are deposited in tunnels with stainless steel tape, which receive strong air currents that lower the temperature of the cuts to -20 or -30 °C. A control panel allows the speed of the belt to be varied. When they leave the tunnel they go to the packaging, which wraps the cut in a special plastic bag that does not allow gases to pass through. The open end is connected to a vacuum bag and sealed. The development of these systems is based on the use of domestic freezers where it is possible to keep products at -18 °C (0 °F) and thus have a reserve of meat at home.

El pescado es más sensible que la carne al ataque de bacterias. Enfriado a temperaturas cercanas a 0 °C tiene una vida útil de pocos días. Como ejemplo: bacalao y salmón 3 días, camarón 2, atún y arenque 1. No queda tiempo para el mercadeo. El procedimiento normal es congelar a -20 °C o más bajo.

Los barcos pesqueros de alta mar están provistos de cuartos frigoríficos donde mantienen la pesca cercana a los 0 °C, o en su defecto en cajas con hielo en escamas o en piletas con agua de mar enfriada a cerca de 0 °C. Los barcos-factorías tienen también cuartos para congelar. De vuelta a la costa, se envía la pesca a la planta de procesamiento más cercana. Si es de peces medianos o chicos, por un caño con corriente de agua de mar, y si son grandes con montacargas. La primera etapa en la planta es la limpieza, que se hace de forma manual o mecánica de acuerdo al precio de la mano de obra y el tipo de pescado. Las operaciones incluyen:.

Para algunas operaciones hay diferentes modelos de acuerdo a la variedad y al tamaño del pescado a procesar.

Frozen

It is carried out in cold rooms with strong air currents at -30 to -40 °C. Large fish such as tuna and cod are hung on rails that run on a rail similar to that of half-carcasses. Fans on the wall perpendicular to the track send strong air currents. The smaller fish are placed in trays that are placed on carts that roll into the room, and on top of them there is an evaporator. A fan attached to the evaporator sends a current to the carts and another at the opposite end absorbs the air that passed through the carts. In this way, a closed circuit is generated that lowers the temperature until it reaches the set temperature. The carts are removed from the room, the trays are removed and another load of fish is placed on trays. If possible, a train of carts is established so that the cart with the frozen load is removed from one end of the room and another loaded with fish to be frozen is introduced at the other end.

Fish or fillets are placed in a freezing tunnel with a stainless steel mesh and fall frozen to the other end by a current of air at a set temperature. An important factor in determining freezing time is thickness. The speed of the air does not have much influence on the speed of the temperature drop depending on the thickness of the fish. The tunnel control panel allows you to vary the different parameters (belt speed, air speed).

Vacuum packed

Home freezers are programmed to maintain a temperature of -18°C (0°F), sufficient for purchasing vacuum-packed frozen fish and fillets. When they leave the belt or the freezing room, they are bagged in gas-impermeable plastic. The bag is vacuumed and sealed.

Pecan is the nut that needs to be kept in the refrigerator at -2 to -4 °C and relative humidity of 60-70%. Before storing, the dry skin of the fruit must be removed. Generally the refrigerator is part of the plant that includes selection, classification, nut splitting and packaging. The other varieties do not require a refrigerator.

Generally the eggs are stored from the period of maximum production until the period of low production. The room temperature should be -1°C and RH 82 to 85%. Eggs absorb odors, so it is recommended to keep them in separate rooms.