A method of chilling poultry carcasses and a chilling system

Abstract

A method of chilling poultry carcasses is disclosed. It comprises A) arranging the poultry carcasses in a first chilling section having an air temperature of 8-18 °C for a first period of 30-75 minutes and applying a water mist having a water temperature of 5-20 °C onto the poultry carcasses at intervals of 5-70 seconds during said first period; and B) arranging the poultry carcasses in a second chilling section having an air temperature of 0-2 °C for a second period of 60-180 minutes. A chilling system comprises: a first chilling section comprising an air inlet and a plurality of water misting nozzles, a first air management system, a water supply system, a second chilling section, a second air management system, and a control unit for controlling the first air management system, the water supply system, and the second air management system.

Description

[0001] Title of Invention

[0002] A method of chilling poultry carcasses and a chilling system

[0003] Technical Field

[0004] The present invention relates to a method of chilling poultry carcasses and to a chilling system for chilling poultry carcasses.

[0005] Background Art

[0006] Air chilling of meat products, such as poultry carcasses after slaughter and removal of the intestine pack, is traditionally carried out in a 0-2 °C atmosphere by blowing cold air at a temperature of about +2 °C directly onto the poultry carcasses at high velocity for a period of 2-3 hours. Thereby, the temperature of the poultry carcasses is reduced from an initial temperature of about +40 °C to +4 °C. In many jurisdictions it is required by law that the temperature of meat products must be brought down to +4 °C or below within a certain time after slaughter.

[0007] The prolonged exposure to the cold air dries out the surface of the poultry carcasses, which may have several adverse consequences.

[0008] When chilling poultry carcasses, the drying may result in a change of colour of the skin of the carcasses, depending on the temperature at which the poultry has been scalded to facilitate defeathering and thus whether the epidermis has been removed or not. Such a change of colour is unwanted in products, which are to be sold with skin on.

[0009] Furthermore, the drying effect of the air will usually result in a weight loss, resulting in a smaller yield, as the price of meat products is typically determined by weight. For poultry carcasses the weight loss will typically be 1-3%.

[0010] This drying effect can to some extent be compensated for by spraying water onto the poultry carcasses, either intermittently or throughout the chilling process. This method is known as evaporative chilling and examples are known from DE3311437A1 and DE3727079A1.

[0011] Evaporative chilling is very effective in preventing discolouration resulting from surface drying, but it does not completely prevent weight loss. For poultry carcasses chilled by evaporative chilling, the weight loss will typically be 0.5-2%.

[0012] A further problem associated with both air chilling and evaporative chilling is that large amounts of energy are used for cooling air and water, for running the fans used for blowing air onto the poultry carcasses, for defrosting cooling evaporators, and for pumping water to the water spray nozzles.

[0013] Summary of Invention

[0014] With this background, it is an object of the invention to provide a method of chilling poultry carcasses and a chilling system by which weight loss and / or energy consumption can be reduced.

[0015] In a first aspect of the invention, this and further objects are achieved with a method comprising the following sequence of steps: A) arranging the poultry carcasses in a first chilling section having an air temperature of 8-18 °C for a first period of 30-75 minutes, and applying a water mist having a water temperature of 5-20 °C onto the poultry carcasses at intervals of 5-70 seconds during said first period; and B) arranging the poultry carcasses in a second chilling section having an air temperature of 0-2 °C for a second period of 60-180 minutes.

[0016] In a second aspect of the invention, the above and further objects are achieved with a chilling system for chilling poultry carcasses, said chilling system comprising: a first chilling section comprising an air inlet and a plurality of water misting nozzles, a first air management system for the first chilling section, a water supply system configured for supplying water to said water misting nozzles, a second chilling section, a second air management system for the second chilling section, and a control unit configured for controlling the first air management system to keep an air temperature in the first chilling section at 8-18 °C, for controlling the water supply system to supply water at a water temperature of 5-20 °C, and for controlling the second air management system to keep an air temperature in the second chilling section at 0-2 °C.

[0017] Below, embodiments of both aspects of the invention will be described together to avoid undue repetition. Embodiments and advantages described with reference to one aspect also applies to the other aspect, unless otherwise stated.

[0018] During the first period, a centre temperature of the poultry carcasses is lowered to approximately 18-25 °C, preferably less than 22 °C. The centre temperature is measured at the hottest part of the poultry carcasses, which is usually the thickest part. For chicken carcasses the temperature, also referred to as deep muscle temperature, is measured at the thickest part of the breast fillet. What is here referred to as chicken are also commonly referred to as broilers.

[0019] The poultry carcasses are subsequently chilled from 18-25 °C to below 4 °C in the second chilling section in a process which may be resembling a traditional air chilling, and the resulting drying will dry out at least some of the water added in the first chilling section. As water will be absorbed in the tissue of the poultry carcasses during the first period (see further explanation below), the drying occurring during the second period will primarily, in most cases exclusively, dry out the skin and the membranes between the skin and the muscles, preserving the full juiciness of the muscles, possibly even with a small weight gain. Furthermore, the original colour of the skin of the poultry can be retained regardless of the drying during the second period, as the skin will contain sufficient moisture after the first period to avoid discolouring.

[0020] The energy consumption for chilling the poultry carcasses from 18-25 °C to below 4 °C in the second chilling section of the system according to the present invention may be reduced compared to the energy use for chilling from 18-25 °C to below 4 °C in the traditional processes, since the second period is relatively long, leading to a reduced need for ventilation and defrosting. It is noted that the relatively long second period does not lead to any food safety risk, as bacterial growth below 18-25 °C is relatively slow and as the second period is still only 60-180 minutes.

[0021] Another potential advantage of the invention is that cut-ability of poultry carcasses may be improved. Tests have shown that poultry carcasses chilled with the method according to the present invention are easier to debone than poultry carcasses chilled by traditional air chilling, and that the final tenderness of the meat after maturation is improved in that the muscles have a lower shear-factor. While the cause of this difference is not yet scientifically proven, it is attributed to rigor mortis developing differently with the relatively slow chilling occurring during the first period, keeping the muscles at more optimal temperatures during rigor development.

[0022] A still further advantage is that as water is only / primarily used in the first, warmer chilling section, the problems with ice formation on the water supply system, cooling evaporators, and water misting nozzles, which are common in evaporative chilling, are significantly reduces, possibly even completely avoided.

[0023] Due to the low temperature difference between the carcasses and the air in the first chilling section, the total chilling time may be prolonged compared to traditional air chilling, but as this will in turn facilitate maturation and improves product quality and cut-up yield, this is considered acceptable.

[0024] The use of a water mist at a relatively high temperature in the first chilling section results in that water penetrates into the tissue of the poultry carcasses. The closer the temperature of the water is to the temperature of the carcasses, the better the water absorption. It may therefore be advantageous to gradually decrease the water temperature over the first period. During the first period, water will penetrate not only into the skin of the poultry carcasses but also into the membranes between the skin and the muscles, and possibly into the muscles.

[0025] The penetration of the water into membranes between the skin and the muscles may reduce drip loss, in that the water-saturated membranes form a moisture buffer and blocks the transport of moisture from the muscles towards the skin.

[0026] In comparison, the relatively cold water sprayed onto the relatively hot carcasses in evaporative chilling is intended to form a water film on the surfaces of the poultry carcasses so that the evaporation of this water may remove heat from the carcasses and at the same time prevent the water present in the tissue from evaporating. Some penetration into the skin will occur, but due to the combination of a high air speed and a high temperature difference between the water and the tissue of the poultry carcasses, only a limited amount of water will reach the membranes between the skin and muscles.

[0027] The relatively high temperature of the water now used in the first chilling section may, depending for example on the climate zone where the slaughter house is located, also lead to a reduced amount of energy being used for cooling the water.

[0028] The relatively warm air now used in the first chilling section is able to contain a large amount of water vapour, resulting in a reduced condensation both in the air and on the surfaces of the poultry carcasses. This in turn leads to a low water consumption and potentially to a reduced amount of energy spent on pumping water.

[0029] A calculated energy consumption for reducing the temperature of an eviscerated poultry carcass weighing 1750 grams from +40 °C to +18 °C during the first period will on average, factoring in seasonal temperature changes in air and water, be less than 75 kJ, compared to at least 140 kJ when using traditional air chilling. For the same poultry carcass, a calculated energy consumption for reducing the temperature from +18 °C to +4 °C in the second chilling section is 90 kJ compared to at least 100 kJ when using traditional air chilling. The total energy consumption for the method according to the invention is thus about 165 kJ for a poultry carcass weighing 1750 grams, compared to 240 kJ for traditional air chilling, corresponding to an energy saving of at least 30% or 900 MJ per hour in a typical poultry slaughterhouse processing 12,000 chickens per hour.

[0030] In these calculations only the amount of energy used for the actual chilling is factored in. A reduction of the energy needed for circulating air and for running condensers to reduce humidity in the second chilling section etc. will entail further energy savings.

[0031] Furthermore, the water consumption can be reduced. When processing chicken from about 0.5 litres per chicken when using evaporative chilling to about 0.3 litres per chicken, resulting in a calculated average water saving of 2.4 cubic meters of water per hour when processing 12,000 chicken per hour.

[0032] The application of water mist at intervals means that poultry carcasses gain water gradually and retain the water throughout the first period. In comparison to the use of a water spray as in evaporative chilling, the misting of the water results in an atomization of the water, which allows the water to be air-born for an extended period of time. This in turn allows the water to be slowly absorbed by the membranes and muscles of the poultry carcass rather than just being deposited on the skin.

[0033] By the indication that a water mist is applied at intervals of 5-70 seconds is understood that after an application of water mist, no water mist is applied for a period of 5-70 seconds, followed by a new application of water mist. The term “interval” is thus to be understood as a period with no active application of water mist.

[0034] In one embodiment, the water mist is applied at intervals of 10-70, preferably 10-50, still more preferably 15-30 seconds for poultry carcasses. Specifically, tests have been conducted on chicken carcasses with an application interval of 15-18 seconds, specifically 16 seconds, showing good results.

[0035] The water mist is applied in water mist application periods each having a duration of 0.5-5 seconds, preferably 1-2 seconds for each interval. The duration of the water mist application periods, i.e. the periods with active application of water mist, may depend on factors such as the amount of mist ejected by the water misting nozzles, on the distance between the carcass and the water misting nozzles, and if baffle plates or the like are provided to protect the water mist. The water mist application period may vary over the first period, for example having longer water mist application periods at the beginning of the first period for building a water film on the poultry carcasses and shorter water mist application periods later in the first period for maintenance of the water film.

[0036] The total duration of a water mist application cycle, i.e. the sum of the duration of the period with active application of water mist and the duration of the period with no active application of water mist, is thus preferably from 5.5 seconds to 75 seconds.

[0037] The duration of the period with active application of water mist and the length of the intervals should ideally be such that a water film is present on the carcass at all times but that there is no formation of drops of water during the first period. This may easily be determined by experiments and adjustments may be necessary to compensate for example for differences in the size or initial temperature of the carcasses.

[0038] To keep the water mist in the air for as long as possible and thus allow the longest possible contact time with the poultry carcasses, the air speed in the first chilling section is low, preferably below 3 m / s and more preferred below 1 .5 m / s.

[0039] To summarize, four factors may contribute to an improved chilling:

[0040] - A relatively longer and slower chilling during the early rigor phase,

[0041] - A low temperature difference between the tissue of the poultry carcasses and the water applied to them,

[0042] - Using a water mist rather than spraying water onto the poultry carcasses, and

[0043] - A low air speed in the chilling section.

[0044] In one embodiment, the first chilling section and the second chilling section are sections of one room, but it is presently considered advantageous that they are separated from each other, so that the poultry carcasses pass a partition, such as a curtain or a door, when they are moved from the first chilling section to the second chilling section. This will make it easier to maintain the different temperatures in the two chilling sections, thus contributing to keeping the energy consumption at a minimum, and may further help to keep the water mist in the first chilling section. Furthermore, the risk of the relatively higher air speed in the second chilling section disturbing the water mist in the first chilling section will be reduced.

[0045] In one embodiment the air temperature in the first chilling section is 12-18 °C.

[0046] In one embodiment, the air temperature in the first chilling section is 15 °C and the first period is 60 minutes. This combination of temperature and duration has been found to provide a good chilling of poultry carcasses.

[0047] In one embodiment, the water temperature of the water used for the water mist is 10 °C. At this temperature the water mist is cold enough to provide a good chilling of the poultry carcasses but is still warm enough to be easily absorbed in the skin of the poultry carcasses. Furthermore, a water mist formed at this temperature stays in the air for a long time.

[0048] In one embodiment, to further optimize the absorption of water, the first period and / or the second period is divided into two or more sub-periods, where the water temperature and / or the air temperature becomes still lower so that it is always close to the temperature of the poultry carcass. As an example, water with a temperature of less than 8 °C, such as 5 °C, may be used at the very phase of the first period in the first chilling section. In another embodiment, an intermediate chilling period, for example with an air temperature of 10 °C, is added between the first and second periods, i.e. between steps A) and B). This may require the provision of a further chilling section.

[0049] Water mist may be applied both onto an outer surface of each poultry carcass and into an inner cavity of each poultry carcass. As the air in the inner cavity will be largely stationary, the application rate of the water mist into the inner cavity may be different from the application rate onto the outer surface. In one embodiment less water mist is applied into the inner cavity than onto the outer surface, in another embodiment water mist is applied into the inner cavity at longer intervals than onto the outer surface, for example applying water mist into the inner cavity only for every other time that water mist is applied onto the outer surface.

[0050] The chilling taking place in the second chilling section may resemble that of traditional air chilling or evaporative chilling, except for the fact that the starting temperature is lower. For this reason, the second period is shorter than a traditional air chilling or evaporative chilling. In one embodiment, which is suitable for chicken, the second period is 120 minutes. The air speed in the second chilling section is typically 2-6 m / s, preferably 2-4 m / s.

[0051] Depending on the air speed in the second chilling section, it may be advantageous to provide one or more water spray nozzles or water misting nozzles in the second chilling section, so that the process in the second chilling section resembles evaporative chilling.

[0052] In traditional air chilling, very cold air is blown onto the poultry carcasses at high speed to quickly carry heat away. In the method according to the present invention, the temperature difference between the air in the first chilling section and the poultry carcasses is much lower, and the air just needs to move sufficiently to maintain an even temperature in the first chilling section. The air speed can thus be lower. It is presently preferred that air is blown through the first chilling section at an air speed of 0.5-3 m / s. To keep disturbance of the water mist at a minimum, an air speed of 0.5-1 .5 m / s is considered advantageous. It is contemplated that the air speed may be different in different sub-sections of the first chilling section and / or that baffle plates or the like may be provided to protect the water mist. Baffle plates may be used simply to direct an air flow away from the water mist and to deliberately create a beneficial flow pattern. Other means for protecting the water mist, such as doors, curtains or air-curtains are also envisaged. Such water mist protection means may be used for forming a physical or flow- induced cabin around the water misting nozzles and the carcass(es) to which the water mist is being applied.

[0053] One or more fans may be used for drawing air into the first chilling section and / or for causing air to move inside the first chilling section.

[0054] The air may be atmospheric air, but it is also possible to use purified air. In one embodiment, purified air is blown in a counter-current moving towards an entrance to the first chilling section, where the poultry carcasses enter the first chilling section.

[0055] A dehumidifier, such as a cooling evaporator, may be provided in or at the air inlet to dry the air before entry into the first chilling section.

[0056] In the intervals between water mist application periods the air surrounding the poultry carcasses should be as dry as possible. To keep the air humidity in the first chilling section low without the need for cooling evaporators, the air in the first chilling section is exchanged at least twice per hour, preferably at least ten per hour, in order to facilitate the necessary air flow.

[0057] To help in maintaining stabile conditions in the chilling sections and hence a chilling process where only little adjustments are required during normal operation, it is considered advantageous that the poultry carcasses are supplied to both chilling sections in a continuous manner. In one embodiment, the poultry carcasses are conveyed through the first chilling section and / or the second chilling section along a travel path, preferably at an even speed. If the poultry carcasses are conveyed through both chilling sections, the chilling system will then comprise a conveyor system configured for transporting the poultry carcasses through the first chilling section and subsequently through the second chilling section along a travel path, where the conveyor system is configured for providing a travel time through the first chilling section of 30-75 minutes and a travel time through the second chilling section of 60-180 minutes, and where the water misting nozzles are arranged at intervals along the travel path so that the poultry carcasses pass water misting nozzles at intervals of 5-70 seconds while travelling through the first chilling section. In other words, the water misting nozzles or sets of water misting nozzles are arranged at a distance from each other along the travel path, said distance being defined by the water mist application intervals and the speed of the conveyor. It is presently considered advantageous that water misting nozzles are arranged in sets, where all water misting nozzles of a set apply water mist to a carcass at substantially the same time. A set may for example include one water misting nozzle applying water mist to the breast of a carcass and one water misting nozzle applying water mist to the back of the carcass.

[0058] The conveyor may be an overhead conveyor where the poultry carcasses hang from shackles or hooks on the conveyor. With the use of an overhead conveyor, all outer surfaces of the poultry carcasses will be exposed to the water mist and the air in the chilling sections.

[0059] The travel path may follow a serpentine pattern to save space.

[0060] While the use of a conveyor travelling from another part of poultry processing facility into the chilling system, through both chilling sections, and back out of the chilling system is presently preferred, it is also possible to use a conveyor extending only through the chilling system. In a further alternative, the conveyor system may comprise a first conveyor in the first chilling section, a second conveyor in the second chilling section, and a transfer unit for transferring the poultry carcasses from the first conveyor to the second conveyor. This would allow the poultry carcasses to be transported at different speeds in the two chilling sections.

[0061] In a still further alternative, the poultry carcasses hang on racks, which are arranged first in the first chilling section and then in the second chilling section. While a hanging position is preferred as it leaves all major surfaces of the poultry carcasses free, the poultry carcasses may also be resting on a surface, such as on a conveyor or on shelves.

[0062] In one embodiment, air is caused to move in a direction across the travel path of a conveyor.

[0063] In one embodiment, at least one water misting nozzle is moveable in a height direction and / or able to move with a poultry carcass travelling on a conveyor. Movement in the height direction may allow the water misting nozzle to be moved into and out of the path of the poultry carcasses, possibly into the inner body cavity of each poultry carcass. Movement with the poultry carcass may allow a longer exposure time to the water mist.

[0064] In one embodiment, the water mist is electrostatically polarized. This may for example be achieved by means of an electrostatic generator connected with one pole to one or more water misting nozzles and the other pole to the poultry carcass. In one embodiment the positive pole is connected to one or more water misting nozzles, and a conductive element connected to the negative pole is arranged so that it comes into contact with the poultry carcasses. By polarizing the atomized water of the water mist and connecting the poultry carcass to the opposite pole, the water is attracted to the poultry carcass, thereby improving the heat transmission provided by the water and potentially reducing the amount of water needed.

[0065] In one embodiment, which may advantageously be combined with the polarization described above, the water supplied to the water misting nozzles by the water supply system is alkaline ionized water. Alkaline ionized water typical has a pH of about 9 compared to a pH of about 6 for fresh chicken meat, and this difference causes the water to bind well to the tissue of the poultry carcasses. Furthermore, alkaline ionized water may have a positive effect on human health. The advantages of using alkaline ionized water in poultry processing is well known to the skilled person and will therefore not be described in further detail here.

[0066] When using alkaline ionized water in poultry processing, it is typically produced on-site with acidic ionized water as a by-product. The acidic ionized water may be applied to the poultry carcass, for example at the transition from the first chilling section to the second chilling section. The low pH is known to have an antimicrobic effect. The application of the acidic ionized water may for example be performed using spray nozzles.

[0067] The invention is primarily described with reference to the chilling of poultry carcasses, but it is to be understood that it may also apply to the chilling of the carcasses of other small animals, such as rabbits or game, and to parts of carcasses, such as hams. When processing poultry carcasses, the water will penetrate the skin, the membranes between the skin and the muscles, and possibly into the muscles. In other types of meat having thicker skin, the water may only penetrate the skin, and in meat without skin the penetration may reach deeper into the muscles. Water penetration will also depend on other factors, such as the size of the carcasses or parts thereof and the meat structure.

[0068] Brief Description of Drawings

[0069] In the following description embodiments of the invention will be described with reference to the schematic drawings, in which

[0070] Fig. 1 is a top view of a chilling system,

[0071] Fig. 2 is side view of poultry carcass at a set of water misting nozzles,

[0072] Fig. 3 is side view of poultry carcass at a set of water misting nozzles in a cabin,

[0073] Fig. 4 is side view of poultry carcass at another set of water misting nozzles,

[0074] Fig. 5 is side view of poultry carcass at a still further set of water misting nozzles,

[0075] Fig. 6 is a perspective view of a carrousel unit with water supply pipes,

[0076] Fig. 7 show test results from two chilling processes, and

[0077] Fig. 8 show test results from three chilling processes.

[0078] Description of Embodiments

[0079] A chilling system 1 for chilling poultry carcasses is shown in Fig. 1 . It comprises a first chilling section 10 and a second chilling section 20, which are separated from each other by a wall 30. A conveyor 4 extends through the entire chilling system, entering the first chilling section 10 through an entry 11 , passing through an opening 31 in the wall 30, and exiting the second chilling section 20 through an exit 21 .

[0080] The conveyor 4 follows a serpentine path so that the length of the travel path of the conveyor inside each chilling section 10, 20 is considerably longer than the length of the chilling section. In the embodiment shown the travel path in each chilling section is almost seven times the length of the respective chilling section in a length direction L, but the optimal length of the travel path will be determined by several factors, such as conveyor speed, air temperature, and the size of the carcasses to be processed. In the embodiment shown in Fig. 1 , the length of the travel path in the second chilling section 20 is slightly more than twice the length of the travel path in the first chilling section 10, so that the poultry carcasses will stay in a second chilling section slightly more than twice as long as they will stay in the first chilling section. If, for example, the conveyor speed is set such that each poultry carcass passes through the first chilling section in 30 minutes, it will take each poultry carcass about 63 minutes to pass through the second chilling section. If the conveyor speed is set such that each poultry carcass passes through the first chilling section in 70 minutes, it will take each poultry carcass about 150 minutes to pass through the second chilling section in the embodiment.

[0081] In Fig. 1 the conveyor 4 is shown with the longer conveyor sections extending between turning wheels 41 and extending in the same direction in both chilling sections, but this need not be the case. Space restraints in a poultry processing facility may require a different layout of one or both chilling sections 10, 20 and / or the conveyor path therein.

[0082] In the drawing, the conveyor 4 is shown only as an overhead conveyor, but other types of conveyors are possible. The use of conveyors in poultry processing facilities is well known to the skilled person and will therefore not be described in detail here.

[0083] The first chilling section 10 comprising an air inlet 12, air outlets 13, and an air management system 14, here illustrated by a series of fans 141. The air management system draws air in through the air inlet 12 and pushes the air towards the air outlet at a slow speed as shown by the arrows. It would also be possible to draw the air through the first chilling section, for example by arranging fans at the air outlets 13, or to use a combination of pushing and drawing. While fans inside the chilling section are used for illustration of the air management system, it is to be understood that any source of overpressure on the air inlet side or underpressure on the air outlet side may be employed.

[0084] A dehumidifier (not shown) may be provided in or at the air inlet 12. The provision of dry air to the first chilling section 10 may reduce the risk of condensation on the walls of the first chilling section and / or on the poultry carcasses. Further, air management devices (not shown), such as an air temperature regulator, a filter, or a mixer for mixing recycled air with fresh air may also be provided.

[0085] A second air management system 24 is provided in the second chilling section 20, also illustrated by a series of fans. The second air management system is configured for circulating air inside the second chilling section as illustrated by the arrows as is the case in a traditional air chilling system. Condensation units (not shown) may be provided to remove moisture from the air.

[0086] The first chilling section 10 further comprises a plurality of sets of water misting nozzles 15 and a water supply system 16 configured for supplying water to said water misting nozzles. As will also be described below, each set of water misting nozzles comprises two or more water misting nozzles. Here 27 sets of water misting nozzles are shown, dividing the travel path through the first chilling section into 28 sub-paths. If the travel time for each poultry carcass through the first chilling section is 30 minutes and each application of water mist takes 2 seconds, this means that water mist will be applied at intervals of about 62 seconds.

[0087] In Fig. 1 the water supply system 16 is illustrated by a supply pipe 161 extending from a set 15 of water misting nozzles to a water temperature regulator 162, such as a water heater, and from there to a water main 50. It is to be understood that all water misting nozzles are connected to the water supply system and that the water supply system may comprise more than one supply pipe, possibly even a supply pipe for each water misting nozzle.

[0088] The chilling system further comprises a control unit 60 configured for controlling the first air management system 14, the second air management system 15, and the water supply system 16. In Fig. 1 the control unit 60 is illustrated as an external unit sending wireless control signals to the first air management system 14, the second air management system 15, and the water supply system 16, but it is also possible to have a wired connection to one or more of them. It is also possible to have sensors (not shown) in the first chilling section and / or the second chilling section sending data, for example about humidity, temperature, or air speed, to the control unit 60. Such sensor signals may be used for regulating the operation of the air management systems and / or the water supply system.

[0089] In Fig. 2-6 the same reference numbers as in Fig. 1 will be used for elements having the same function, even if they are not identical. Only differences between the different embodiments will be described.

[0090] Fig. 2 shows a set of water misting nozzles 151 , 152, 153 arranged on pipes 163 of the water supply system 16 and applying a water mist 2 onto a poultry carcass 3.

[0091] The poultry carcass 3 has been plucked and opened at the cloaca and the viscera has been removed via the resulting opening, leaving an empty inner body cavity 33.

[0092] The set of water misting nozzles in Fig. 2 comprises three water misting nozzles, one 151 applying water mist onto the breast 31 of the poultry carcass, one 152 applying water mist onto the back 32 of the poultry carcass, and one 153 applying water mist into the inner body cavity 33 of the poultry carcass shown by the broken line.

[0093] In the embodiment shown in Fig. 2, two valves 164, 165 are used for regulating the water supply to the water misting nozzles 151 , 152, 153, and these valves are configured for receiving control signals from the control unit 60 (shown only in Fig. 1 ). Here one valve 164 regulates the water supply to all water misting nozzles and the other valve 165 regulates only the water supply to the water misting nozzle 153 applying water mist to the inner cavity 33 of the poultry carcass. This allows the application of water mist to the inner cavity to be kept off or interrupted while water mist is applied to the breast 31 and the back 32 fo the carcass 30. This may be advantageous in that the inner body is less exposed to air during the chilling process and thus less exposed to water loss. It would also be possible to have one valve for each water misting nozzle, for example allowing the application of water mist only to the breast 31 , where the muscles are thicker than at the back and where the quality of the skin is of higher importance to the value of the poultry product. These considerations apply to all embodiments, not only the one shown in Fig. 2. It is even possible to leave out the water misting nozzle 152 at the back side. The water mists 2 shown in Fig. 2 are applied to the entire breast 31 and to the entire back 32 of the poultry carcass 3 using one water misting nozzle 151 , 152 at each side, but it would be possible to use more than one nozzle at each side, for example one applying the water mist in a slightly upward direction and one applying the water mist in a slightly downward direction. It is to be understood the water misting nozzles 151 , 152 applying water mist to the breast 31 and to the back 32 will also be applying mist to the leg 34 of the poultry carcass, and that it will be possible to add further water misting nozzles directed towards the legs of the poultry carcass.

[0094] Water misting nozzles 15, 151 , 152, 153 may be moveable to allow a repositioning in response to a change in the size of the poultry carcasses 3 being processed, and / or to allow them to cover a bigger area of the poultry carcass. This applies to all embodiments, not only the ones in Fig. 1 and Fig. 2.

[0095] The position of the fans 141 relative to the water misting nozzles 15, 151 , 152, 153 and / or the timing of the operation of the fans 141 may also be such that poultry carcasses 3 on the conveyor 4 shield the cones or fans of water mist by reflecting air.

[0096] In Fig. 2 the poultry carcass 3 hangs from a shackle 42 attached to a bracket 43 with wheels 44 running on an overhead rail 45, but, as mentioned above, other types or conveyors, racks, or other means for supporting a poultry carcass may also be used. The overhead conveyor shown in Fig. 2, however, has the advantages that only the ends of the legs 34 of the carcass, which have very limited need for chilling, is in contact with the conveyor, leaving all other surfaces of the carcass free and exposed to air and water mist.

[0097] In Fig. 3 a set of water misting nozzles identical to the set shown in Fig. 2 is provided inside a cabin 7 to protect and retain the water mist 2 ejected by the water misting nozzles 151 , 152, 153. In addition to allowing the water mist to stay in the air for longer, the cabin may also reduce the amount of water mist carried along by the poultry carcasses 3, thereby also contributing to maintaining a relatively dry atmosphere between sets of water misting nozzles, i.e. in the intervals with no active application of water mist.

[0098] The cabin is provided with door openings 71 in the front wall 74 (shown as transparent in Fig. 3) and in a corresponding back wall (not visible) on the opposite side, and the conveyor rail 45 extends through the cabin so that poultry carcasses 3 enter the cabin via the door opening in the back wall and exits via the door opening 71 in the front wall.

[0099] In the embodiment shown, the cabin 7 is provided with a water outlet 72 in the bottom wall 75, allowing condensed water to be drained off, and a mist outlet 73 in the top wall 76, allowing ventilation or extraction of excess water mist. These outlets 72, 73 may be provided with pumps, fans, or valves to facilitate mist and water management and / or the openings provided by these outlets may be used for air management purposes, for example for the injection of cold air in case the temperature inside the cabin becomes too high. Sensors (not shown) may be provided inside the cabin 7 to measure temperature and air humidity.

[0100] More than one set of water misting nozzles may be provided in same cabin, thus allowing a prolonging the period of active application of water mist without decreasing the travel speed of the conveyor 4.

[0101] In Fig. 3 the cabin 7 is a physical cabin build for example from plates of stainless steel, which is easy to keep clean, but it is also possible to use curtains, made for example from plastic, or air-curtains formed by vertical air streams. A combination is also possible, for example using air curtains instead of the front wall 74 and the back wall. The door openings 71 will then not be necessary as the carcasses will simply pass through the air-curtain.

[0102] When using curtains or air-curtains, a water outlet 72 may not be necessary as there will usually be no bottom wall and no top wall.

[0103] A back wall may not be necessary, as the movement of the poultry carcasses 3 will create an air-flow towards the front wall 74 into the cabin 7.

[0104] Fig. 3 further shows a set of baffle plates 8 at the water misting nozzles 151 , 152 ejecting water mist 2 towards the back and breast of the carcass 3. The baffle plates protect the cones or fans of water mist by reducing air movement in the area between them and may be particularly advantageous when using air-curtains instead of the physical side walls 77 shown in Fig. 3.

[0105] In this case the baffle plates 8 are bowl-shaped to embrace the water mist 2, but planar baffle plates may also be used and / or sets of baffle plates maybe used for creating a similar effect.

[0106] Baffle plates may also be provided at the water misting nozzle 153 applying water mist to the inner cavity of the poultry carcass.

[0107] Even though the baffle plates 8 are here shown as being arranged inside a cabin 7 it is to be understood that they may be used also in embodiments with no cabins and that the baffle plates themselves may be used for forming a semi-open cabin, thus providing many of the benefits described above with reference to the cabin.

[0108] Fig. 4 shows another embodiment of the water supply system 16. The configuration of the pipes 163 is substantially the same as in Fig. 2, but only one valve 164 regulates the water supply to the water misting nozzles 151 , 152, 153. It is to be understood that there could be more valves as described with reference to Fig. 2.

[0109] In the embodiment in Fig. 4 each water misting nozzle 151 , 152, 153 is connected to the positive pole of an electrostatic generator 5 by wires 51 and the negative pole of the electrostatic generator is connected to the poultry carcass 3 by wires 52. This will cause the atomized water of the water mist to become electrostatically polarized, which may improve heat transmission in the water, and / or help to reduce bacterial growth.

[0110] In Fig. 4 the connection to the poultry carcass is direct in that two conductive elements, here a conductive plate 53 and conductive rod 54, are arranged so that they come into contact with the neck 35 of the poultry carcass as it is moved forward by the conveyor 4. The presence of both the conductor plate 53 and the conductive rod 54 ensures a good contact with all poultry carcasses. If, for example, one or more poultry carcasses are very small, the necks may not reach down to the conductor plate 53 and the conductive rod 54 will then ensure contact. Likewise, poultry carcasses, where the skin on the neck has been removed will not reach as far down as shown in Fig. 4. It may, however, be sufficient to use one of them as the poultry carcasses processed are usually quite uniform. Changes from processing bigger poultry carcasses, such as broilers, to processing smaller poultry carcasses, such as poussins, or vice versa may be compensated for by making the conductor plate 53 and / or the conductive rod 54 moveable in relation to the conveyor in a height and / or a width direction.

[0111] It is to be understood that the conductor plate 53 and the conductive rod 54 are merely examples of electrical conductors and that other sizes or shapes might be used.

[0112] While the conductor plate 53 and the conductive rod 54 are shown as being in contact with the neck 35 in Fig. 4 it is to be understood that one or both they could be in contact with other parts of the poultry carcass 3.

[0113] The connection between the electrostatic generator 5 and the poultry carcass 3 may also be indirect. As an example, if using shackles 42 made of steel or another electrically conductive material, these may come into contact with the conductor plate 53 and / or the conductive rod 54, which would then be arranged at level with the shackle. It is also possible to use a combination of direct and indirect contact.

[0114] The electrostatic generator 5 may be arranged inside the first chilling section 10 or outside, and one electrostatic generator may be connected to more than one set of water misting nozzles 15, 151 , 152, 153, just as one or more water misting nozzle may be without connection to the electrostatic generator.

[0115] A still further embodiment is shown in Fig. 5, which is a cross-section along the line IV-IV in Fig. 6.

[0116] As seen in Fig. 5, two water misting nozzles 152, 154 are provided at different heights in a height direction H at the back side of the poultry carcass 3, each water misting nozzle being provided on a pipe 1632, 1634 of the water supply system.

[0117] The water misting nozzle 151 applying water mist to the breast side of the poultry carcass and the water misting nozzle 153 applying water mist to the inner cavity in Fig. 5 are provided on a support element 61 , which can be displaced on a support rod 62 of a carrousel unit 6. The carrousel unit 6 turns at the same speed as the travel speed of the conveyor 4 so that the support rod 62 and the support element 61 remains with the same poultry carcass 3 as it passes the carrousel unit. The support element is provided with a projection 63, such as a wheel, travelling in a guide track 64 in a guide block 65 of the carrousel unit 6. The guide block is stationary and the position of the guide track 65 in the height direction H is different along the path travelled by the poultry carcasses so that the contact between the projection 63 and guide track 64 forces the support element down and up along the support rod 62. This in turn causes the water misting nozzles 151 , 153 to move down and up. In this way the water misting nozzle 153 applying water mist to the inner cavity of the poultry carcass 3 can be lowered towards the opening in the poultry carcass, possibly even into the inner cavity, thereby increasing the amount of water mist reaching into the inner cavity. Carrousel units of this types are well known to the skilled person from other poultry processing apparatuses, such as eviscerators. Other means for lowering and raising a water misting nozzle may also be applied.

[0118] To allow the movement of the support element 61 , water is supplied to the two water misting nozzles 151 , 153 arranged thereon via a flexible hose 1631.

[0119] It is to be understood that a carrousel unit as shown in Fig. 6 is primarily suitable for use at the positions corresponding to those indicated by the turning wheels 41 in Fig. 1 and that all of the sets 15 of water misting nozzles in Fig. 1 thus cannot be embodied in this way. As the inner cavity of the poultry carcasses will usually require less water mist as described above, it may be sufficient to provide the sets of water misting nozzles shown at the turning points in Fig. 1 with water misting nozzles 153 applying water mist into the inner body cavity, whereas the remaining sets may include only water misting nozzles applying water mist onto the breast and back of the poultry carcasses as illustrated by the water misting nozzles 151 , 152, 154 in Figs 2- 5. It is, however, also possible to provide the guide track 64 in a planar guide block 65 or a guide plate, thereby allowing the down and up movement to be achieved in the same way while travelling along a linear path.

[0120] The embodiments shown in Figs. 2-5 may all be found in the same chilling system. As an example, the polarization described with reference to Fig. 4 may happen only towards the end of the first period, so that the water residing on / at the surface of the poultry carcasses when entering the second chilling section is ionized. Likewise, it is to be understood that cabins and baffle plates as those shown in Fig. 3 may be provided also at water misting nozzles with polarization as described with reference to Fig. 4 and / or with height adjustment as described with reference to Figs. 5-6. In later case, the size and shape of the cabin may need to be adjusted to provide space for the movement of the water misting nozzles.

[0121] Turning now to Fig. 7, the changes in temperature in two chicken carcasses chilled by the method according to the invention are shown. The X axis represents the duration of the chilling process in minutes, and the Y axis represents temperature in degrees Celsius (°C) measured at the centre of both breast filets (deep muscle temperature) of a slaughtered and eviscerated chicken. The upper curve A represents average temperatures measured in a chicken carcass weighing 1747 grams, and the lower curve B represents average temperatures measured in a chicken carcass weighing 1334 grams. The two vertical lines at 64 minutes and 72,5 minutes delimiting a time interval C represent the time used for transferring the chicken carcasses from the first chilling section to the second chilling section, which were arranged at a distance from each other in this test. If using a chilling system as shown in Fig. 1 , this time interval C would be considerably shorter, possibly even zero. The air temperature in the first chilling section was 13-15 °C and water mist having a water temperature of 10-11 °C was applied onto the chicken carcasses by 3 water misting nozzles placed at intervals of 16 seconds during said first period while maintaining an air speed of 0.5-1.5 m / s. The air temperature in the second chilling section was 2 °C and the air speed was 2-3 m / s. As may be seen, the larger chicken carcass, represented by curve A, ended with an average temperature in the breast filets of 3,5 °C and the smaller chicken carcass, represented by curve B, ended with an average temperature in the breast filets of 2,5 °C. Both are below the 4 °C, which is the required maximum temperature in most jurisdictions.

[0122] Similar slaughterhouse tests have shown that the temperature of the chicken carcasses can be reduced from 39.6 °C to 18.3 °C after 60 minutes at a weak air exposure at a room temperature of 14.7 °C, with addition of water mist at intervals of 16 seconds, with in a weight increase of 4.5%. Further experiments have shown a weight increase of 2-5%.

[0123] Fig. 8 shows the changes in weight of chicken carcasses chilled by three different method of chilling. The X axis represents three different stages of the chilling process, and the Y axis represents average weights of the chicken carcasses in grams. The first set of datapoints at X1 represents the initial average weights of the slaughtered and eviscerated chicken carcasses after washing of the poultry carcasses, and the last set of datapoints at X3 represents the averages weights at the end of the chilling processes. Graphs E and F are based only of these two datapoints. Graph D further includes a datapoint at X2, representing the average weight of the slaughtered and eviscerated chicken carcasses after the completion of the first period, corresponding to the weight at the interval C in Fig. 7. The three graphs are based on the following test data:

[0124] Graph D - method according to the invention

[0125] Weight in

[0126] Weight in Weight in grams after

[0127] Carcass grams, inigrams after Weight second Weight no. tial first period gain, % period gain, %

[0128] 1 1683 1814 7,78 1725 2,50

[0129] 2 1615 1727 6,93 1637 1 ,36

[0130] 3 1507 1561 3,58 1529 1 ,46

[0131] 4 2081 2098 0,82 2071 -0,48

[0132] 5 2062 2086 1 ,16 2059 -0,15

[0133] 6 2021 2150 6,38 2063 2,08

[0134] 7 1398 1556 11 ,30 1445 3,36

[0135] 8 1603 1624 1 ,31 1602 -0,06

[0136] 9 2084 2105 1 ,01 2079 -0,24

[0137] 10 1628 1690 3,81 1652 1 ,47

[0138] Average 1768 1841 4,41 1786 1 ,13 The first period was 60 minutes, and the second period was 120 minutes. The air temperature in a first chilling section was 14,7 °C and water mist having a water temperature of 10,8 °C was applied onto the poultry carcasses by three water misting nozzles, two at the breast side and one aiming at the inner body cavity, at intervals of 16 seconds during said first period while maintaining an air speed of 0,5-1 , 5 m / s. The air temperature in the second chilling section was 2 °C and the air speed was 2-3 m / s.

[0139] Graph E - Evaporative chilling

[0140] Weight in grams

[0141] Carcass Weight in after Weight no. grams, initial chilling gain, % 1 1552 1534 -1 ,16

[0142] 2 1550 1535 -0,97

[0143] 3 2178 2155 -1 ,06

[0144] 4 1631 1619 -0,74

[0145] 5 1391 1376 -1 ,08

[0146] 6 1310 1298 -0,92

[0147] 7 1507 1501 -0,40

[0148] 8 2105 2085 -0,95

[0149] 9 1336 1314 -1 ,65

[0150] 10 1955 1938 -0,87

[0151] Average 1652 1636 -0,98

[0152] The chilling process had a duration of 150 minutes. The air temperature was 0-2 °C, the air speed was of 2-4 m / s, and water having a tempera- ture of 1-2 °C was applied onto the poultry carcasses by 2 water spray nozzles, placed at intervals of 180 seconds during the first 130 minutes of chilling.

[0153] Graph F - Air chilling

[0154] Weight in

[0155] Carcass Weight in grams Weight no. grams, initial after gain, % chilling

[0156] 1 1955 1916 1 ,99

[0157] 2 1593 1554 2,45

[0158] 3 2248 2198 2,22

[0159] 4 1974 1942 1 ,62

[0160] 5 2270 2215 2,42

[0161] 6 1781 1746 1 ,97

[0162] 7 1848 1817 1 ,68

[0163] 8 2182 2135 2,15

[0164] 9 2173 2132 1 ,89

[0165] 10 1596 1562 2,13

[0166] Average 1962 1922 2,05

[0167] The chilling process had a duration of 150 minutes. The air temperature was 0-2 °C, and the air speed was of 2-4 m / s.

[0168] As seen from the graphs E and F, all chicken carcasses chilled by evaporative chilling and air chilling in these tests experienced a weight loss. The chicken carcasses chilled by the method according to the present invention gained a considerably amount of weight during the first period, represented by the part of graph D between X1 and X2, and then lost some, but not all, of it again during the second period, represented by the part of graph D between X2 and X3.

[0169] The average weight gain in the first chilling section in further experiments performed according to the present invention have been 2-8%.

Claims

Claims1 . A method of chilling poultry carcasses, said method comprising the following sequence of steps:A) arranging the poultry carcasses in a first chilling section having an air temperature of 8-18 °C for a first period of 30-75 minutes, and applying a water mist having a water temperature of 5-20 °C onto the poultry carcasses at intervals of 5-70 seconds during said first period; andB) arranging the poultry carcasses in a second chilling section having an air temperature of 0-2 °C for a second period of 60-180 minutes.

2. A method according to claim 1 , where the air temperature in the first chilling section is 15 °C and the first period is 60 minutes.

3. A method according to claim 1 or 2, where the water temperature is 10 °C.

4. A method according to one or more of the preceding claims, where the water mist is applied at intervals of 15-45 seconds, preferably 15-30 seconds, still more preferably 15-18 seconds.

5. A method according to one or more of the preceding claims, where water mist is applied in water mist application periods each having a duration of 0.5-5 seconds, preferably 1 -2 seconds for each interval.

6. A method according to one or more of the preceding claims, where the second period is 120 minutes.

7. A method according to one or more of the preceding claims, where air is blown through the first chilling section at an air speed of 0.5-3 m / s, preferably 0.5-1 .5 m / s.

8. A method according to one or more of the preceding claims, wherea centre temperature of the poultry carcasses is lowered to 18-25 °C during the first period.

9. A method according to one or more of the preceding claims, where the poultry carcasses are conveyed through the first chilling section and / or the second chilling section along a travel path, preferably at an even speed.

10. A method according to claims 9, where air is caused to move in a direction across the travel path.

11. A method according to one or more of the preceding claims, where water mist is applied both onto an outer surface of each poultry carcass and into an inner cavity of each poultry carcass.

12. A method according to one or more of the preceding claims, where the air in the first chilling section is exchanged at least twice per hour, preferably at least ten times per hour.

13. A method according to one or more of the preceding claims, where the water mist is electrostatically polarized.

14. A method according to one or more of the preceding claims, where the length of the water mist application periods and the length of the intervals are adjusted such that a water film without water drop formation is present on the poultry carcasses through the first period.

15. A chilling system for chilling poultry carcasses, said chilling system comprising: a first chilling section comprising an air inlet and a plurality of water misting nozzles, a first air management system for the first chilling section, a water supply system configured for supplying water to said watermisting nozzles, a second chilling section, a second air management system for the second chilling section, and a control unit configured for controlling the first air management system to keep an air temperature in the first chilling section at 8-18 °C, for controlling the water supply system to supply water at a water temperature of 5-20 °C, and for controlling the second air management system to keep an air temperature in the second chilling section at 0-2 °C.

16. A chilling system according to claim 15, where the water misting nozzles are arranged in sets comprising at least two of a water misting nozzle configured for applying water mist onto a breast of poultry carcasses, a water misting nozzle configured for applying water mist onto a back of poultry carcasses, and a water misting nozzle configured for applying water mist into an inner cavity of poultry carcasses.

17. A chilling system according to claim 15 or 16, further comprising a conveyor system configured for transporting the poultry carcasses through the first chilling section and subsequently through the second chilling section along a travel path, where the conveyor system is configured for providing a travel time through the first chilling section of 30-75 minutes and a travel time through the second chilling section of 60-180 minutes, and where the water misting nozzles are arranged at intervals along the travel path so that the poultry carcasses pass water misting nozzles at intervals of 5-70 seconds while travelling through the first chilling section.

18. A chilling system according to claim 17, where the conveyor system comprises a first conveyor in the first chilling section, a second conveyor in the second chilling section, and a transfer unit for transferring the poultry carcasses from the first conveyor to the second conveyor.

19. A chilling system according to one or more of claim 15-18, whereat least one water misting nozzle is moveable in a height direction and / or able to move with a poultry carcass travelling on a conveyor.

20. A chilling system according to one or more of claim 15-19, further comprising an electrostatic generator having a positive pole and a negative pole, where the positive pole is connected to one or more water misting nozzles, and where a conductive element connected to the negative pole is arranged so that it comes into contact with the poultry carcasses.

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