INVENTOR: Thorsteinn I. Viglundsson

TITLE OF THE INVENTION:

PRODUCTION AND USE OF DEWATERED ICE-SLURRY

BACKGROUND OF THE INVENTION

Consumers are increasingly favoring fresh food above frozen as is seen by numerous market trends, in particular for fish and poultry products. As preservation such as freezing, will kill many bacteria and prevent microbial growth and slow down internal deterioration of the tissue, such as by oxidation, and hydrolysis, that is often caused by internal enzymes. Keeping cooled fresh food safe and of acceptable quality for the consumers as long as possible (i.e. long shelf-life) is therefore of major concern for health authorities around the world, and at the same time of major economic importance for the producers.

The quality and shelf-life of fresh food depends on many characteristics and conditions, especially factors such as hygiene and handling, during pre- and post-processing (from catch/sacrifice to in-house processing). Bacterial growth, enzyme activity, physical damage, dehydration, chemical reactions and contamination are the main causes of quality loss in fresh foods such as fish and chicken. The importance of precooling before processing and during transport to the consumer therefore cannot be over-emphasized and is gradually being better understood and accepted by the producers and consumers. Here the control of temperature during processing, storage and transport is the main issue.

The main obstacles to gaining the highest desirable shelf life of fresh food products during processing, storage and transport are high temperatures, temperature fluctuations and cross-contamination leading to higher loads of certain spoilage bacteria. At low temperatures, such as below 0°C for fish and below 3°C for meat, there is a significant reduction in microbial growth rates and in the corresponding deterioration of the product due to microbial activity.

It is not desirable to go beyond the initial freezing temperature of the tissue in foodstuffs since that implies that some of the water freezes and the concentration of solutes in unfrozen solutions increase. This may lead to denaturation of the muscle proteins as well as structural damage of membranes, which can result in increased drip loss, loss of water holding capacity and textural changes. Experiments have shown that the temperature of maximum cooling activity for fish is in the region of -2 to -1 °C (Johnston et al., 1994). If the product is cooled very close to its freezing point (Tf) during precooling, rapid cooling is necessary to ensure formation of small ice crystals within the product structure and minimize textural damages of the muscle (Valtysdottir et al. 2010).

Various methods are well known in the art to cool fresh foods rapidly after harvesting, catch or slaughter, including contacts with cold surface, blowing with super cold air, spraying with cold water, covering with plate ice or cold gelpacks or soaking into tanks with ice-slurry. Sometimes these methods are used in combination for example as combination of air blast and contact cooling thought by Arnarsson and Norddahl 2004 (US Patent 6,825,446) or air blast and surface freezing combined with spraying cold water as thought by Butler 2002, (US Patent 6,481,220).

In addition to flesh deterioration and bacterial spoilage that can happen when the cooling process is slow, a further problem with slow cooling, especially of carcasses from warm-blooded animals, is that they lose moisture which can result in significant weight-loss of the order of 1-3%. Such weight loss is even increased in super cold air, which by nature is very dry. Treating animal carcass with freezing cold air can also result in unwanted discoloration of the skin. Therefore a process that can combine both very rapid cooling and minimize weight loss is highly desirable. Since ice-slurry is typically made from salt- containing water and contains very fine ice crystals with temperatures below 0°C, it is known to be an extremely efficient cooling agent. However, the simple way of using it for rapid cooling by immersing perishable foods, such as meat, fish or vegetables into ice-slurry tanks, is no longer recommended. This is because bacteria are washed off the carcass and tend to accumulate in such immersion tanks and that will therefore facilitate the spreading of pathogenic bacteria from one animal throughout the production chain. The current invention relates to new ways to use the highly desirable cooling, and non-drying properties of ice- slurry, by using it directly and separately on individual carcasses or food parts, where it can melt and leak off during the cooling, and thereby avoiding the problems associated with soaking the food components into a common cooling bath.

The production and use of ice-slurry, (also called slurry-ice, binary ice or liquid ice), is well known in the prior art. Ice-slurry has been produced by crushing freshwater ice and mixing with water and salt or by generating ice crystals with a scraped heat exchanger, as well as with other methods. The method of producing ice-slurry depends on its use, but most commonly applied in food processing, where the ice-slurry comes in direct contact with the food or where it must be pumped, a scraper type ice-slurry generator is used (Slurry-ice Based Cooling Systems Application Guide, http://www.epsltd.co.uk/slurry_ice.htm) In the scraper type generator, a brine solution at various temperatures goes into the generator at one end and ice is formed on the side walls, which is continuously scraped off and moved to the outlet at the other end of the generator. The scraping action also agitates the ice-slurry produced and keeps it flowing until it exits the generator.

In the use of ice-slurry, it is typically pumped to the location where it is applied and used or being stored in a tank as an intermediate storage before being pumped to the location where it is applied. Ice-slurry is most commonly produced from water that contains different concentrations of solutes, such as salts, most commonly NaCl in different concentrations. The concentration of ice and salt as well as the freezing energy used is controlled during production and can change during pumping, mixing in the tank, or when being applied. The ice-slurry solution can have a different composition at the place of application, compared to when it was made. The various internal factors, melting of the ice crystals due to thermodynamic changes, loss of energy due to contact with the outer walls of the pipes and tank, energy transferred to the ice from the pumps and other factors can have a big influence on the characteristics of the ice-slurry solution. Therefore, unless specifically monitored and controlled during the whole process or at the point of use, there is no certainty of the temperature, salt concentration or cooling capacity, or physical properties the ice mixture as the ice crystals can melt or grow, become aggregated or forming clumps. These factors make the use of ice-slurry difficult in many applications. Upon freezing of water, the ice-crystals tend to be formed from only water molecules, excluding any solutes in the water and thereby in effect separating the solute molecules that will become more concentrated in the remaining-un-frozen water. By physical separation of the ice-crystals from the remaining liquid part, purified water can be obtained from melting the ice, whereas the solutes have also become isolated or concentrated in another fraction. Obtaining large and pure, or purified ice- crystals that can easily be separated from the remaining liquid is therefore the key issue for many applications of ice-slurry (Bellas and Tassou, 2005). Different separation techniques have been used for dewatering ice-slurry, including centrifugation and filtration such as thought by US Patent 5,816,057. However, although filtration is a simple and highly desirable technique to use for this purpose, it can be problematic since many filters tend to get clogged upon extended use and therefore lose their function, unless a special mechanism of cleaning or regeneration is included in the process.

In the present invention we have found a practical way to apply the principle of filtration for continuous dewatering of ice-slurry by using a revolving chamber concept, where by using two or three revolving chambers, or any multiples thereof, the process of loading, dewatering and delivering (or shooting) the ice-slurry can all be performed in a continuous manner, where a cleaning step by a quick reverse flow on the filter can also be included if needed. SUMMARY OF THE INVENTION

In the present invention we describe the characteristics of an apparatus and method for processing ice-slurry in such a way that the ice-slurry is first produced in ice-slurry generator, then transferred, typically by pumping into an accepting chamber, from where the ice-slurry is then transferred into a second chamber, where the ice-slurry is filtered and removing the liquid part and leaving behind an ice-slurry now dewatered or at least containing less liquid than before. Finally the ice-slurry is moved to the last chamber form where it is delivered or shot by pressure onto a targeted object. The ice-slurry adheres for some time and melts slowly, thereby cooling the object. The targeted object can be any kind of perishable goods, such as animal carcass or any parts thereof, also other types of food products, such as fish, vegetables, fruits or also non-biological products.

The present invention also relates to the use of an apparatus that makes ice-slurry from aqueous solutions containing different concentrations of dissolved materials made of salts and/or other solutes, thereby making ice-slurry composed of a mixture of ice and liquid of different proportions. The ice-slurry so produced where the ice-component contains lower concentration of the dissolved material than the original solution and where the liquid- component contains higher concentration of the dissolved material than the original solution.

The apparatus of the invention can furthermore contain other components such that the temperature of the produced ice-slurry can be controlled.

The invention furthermore contains components that allow separation of parts of the liquid-component from the ice-component in such a way that the ice-slurry so produced has a lower total concentration of the dissolved materials than was present in the original aqueous solutions used to feed into the apparatus.

In certain embodiments the invention can also be used for desalination or for treating different kinds of wastewater, such as animal urine, to make purified water and concentrated solution of salts and other solutes found in the original liquid from where the ice-slurry was made.

In another aspect the invention can be made in such a way that the different actions performed to separate ice and liquid can all be performed in the same chamber but where different sides of the chamber can be opened or closed in such a way that the actions of receiving the ice-slurry, filtering the ice-slurry and finally delivering the dewatered ice-slurry to a target, can all be performed in one chamber.

The apparatus of the invention can be made by using any number of different materials available to those skilled in the art, or combination of different types of materials. Such materials include, but are not limited to, various metals or metal alloys, or glass, or organic materials such as wood or synthetic materials such plastics.

In certain embodiments of the invention, the described chambers of the apparatus used to perform the necessary actions of the invention are positioned in separate plates or cylinders with a shaft running through them so that by turning the shaft different chambers can be opened or closed as needed to perform the actions described in the invention.

In certain embodiments of the invention the apparatus can be controlled via a preprogrammed computer and software or as a coordinated task involving valves and switches coordinated beforehand and running in a prefixed/preprogrammed manner. Likewise the measurement of salt, energy and other factors listed can be based on preprogrammed measurements in the system or through exact measurements in each chamber and pipelines leading to the chamber. Such measurements of the results of the chilling can be fed back to the control of the system to intensify and increase/decrease salt, energy, frequency of the delivery as well as length or volume of the chamber.

In one aspect of the invention, the ice-slurry is applied through a pipeline and used to cover pieces of fresh foodstuffs, such as of fish or chicken in a process chain or on a conveyor belt such that the amount of the ice-slurry applied and the time of contact of the ice-slurry with the pieces can be controlled. Furthermore in such a process chain or on a conveyor belt the temperature of the pieces can be monitored such as to control the temperature and contact- time of the ice-slurry in order to obtain the desired cooling of the pieces in the process. To ensure that the correct amount of ice is used, the quantity, temperature and mixture is calculated, mixed and then applied.

In another aspect of the invention, the apparatus is used to deliver or shoot a certain amount of ice-slurry, with the correct temperature, cooling energy, viscosity, salt content, frequency and amount to chill the foodstuff in the correct, predefined manner and at the correct area on the foodstuff.

In certain embodiments the invention can be incorporated into a food processing chain, such as if attached to a conveyer belt that is moving animal carcasses, such as poultry, after slaughter and feather removal and by controlled delivering of dewatered ice-slurry onto a carcass can be used for rapid cooling and for controlling the temperature of the carcass parts in the process line.

In certain embodiments the invention can be incorporated into a food processing chain, such as if attached to a conveyer belt that is moving parts of meat or fish between processing stations and by controlled delivering of dewatered ice-slurry onto the parts can be used to control the temperature of the food parts in the process line.

In another aspect of the invention, the apparatus is used to separate ice and liquid from an ice-slurry mixture and thereby delivering a clean portion of ice on one side and liquid with concentrated solutes in the other side. In this aspect the invention can be used in treating of wastewater, such as animal urine.

The invention also contemplates certain methods for carrying out concentrations of the soluble materials present in the original aqueous feed solution used for making the ice-slurry. In this aspect the invention can be used to increase the concentration of solutes before applying more expensive concentrations methods, such as ultrafiltration, distillation or drying. In one embodiment, the invention is a method for controlled precooling of foodstuffs before packaging in insulated packaging boxes for transport.

In another aspect the invention can be used to make dewatered ice-slurry for incorporating into transport containers, such as to control the temperature of foodstuffs during storage and transportation.

The invention uses known chemical and physical principles to combine in a new way a set of actions and design of an apparatus that makes the actions possible and therefore useful and commercially viable. The invention is therefore an efficient method and is expected to be useful and consequently to have large potential for industrial application and commercial use. The current invention is thus non-obvious and provides a clear inventive step compared to prior art.

Additional features and advantages of the present invention are described in, and will be apparent from, the following Detailed Description of the Invention and the figures. BRIEF DESCRIPTION OF THE FIGURES Figure 1 shows a drawing of the apparatus in a transection view with the three plates housing the different chambers and inlet and outlet pipes for different functions. Figure 2 shows a drawing of the apparatus from the front viewing the front plate with the inlet and outlet pipes for different functions into the respective chambers. Also the position of the transect A-A indicated. Figure 3 shows a drawing of the apparatus with view of the front plate and the middle plate with the broken lines indicating the chambers in the middle plate that can be rotated with the turning of the shaft. The figure further demonstrates the operation of the invention when the middle plate is turned as indicated by the dotted lines and the numbers as follows: 3.1; Ice- slurry suctioned into chamber through tube 6 and filtration starts, 3.2; The chamber has moved 90° over to tube 7 where further dewatering by suction occurs. 3.3; The chamber has moved 180° over to tube 8 where further actions can happen if needed. 3.4; the chamber has moved 270° of the opening where the dewatered ice-slurry is now delivered/shot by pressured air onto the target. Figure 4 shows a drawing of the apparatus in whole and as being applied to deliver ice-slurry onto and into the cavities of a chicken hanging on a conveyer belt. Figure 5 shows a photograph of the apparatus being applied for cooling fresh chicken on a conveyer belt in real-life commercial settings. The figure shows a real-life photograph of using a prototype apparatus of the invention to deliver the dewatered ice-slurry onto the surface of chicken carcass on a conveyer belt. The chicken was treated in a commercial setting after it had been through a feather picking machine at 57°C, from where it goes onto the conveyer belt for removing of internal organs and opening of the neck along with the repeated washing in between. The chicken then enters the cooling room where it is normally cooled by cold air and cold water spraying. It would be possible to station the apparatus of the invention at several places during this process. In this example the chickens were treated inside the cooling room but removed from the conveyer belt for the controlled demonstration. Figure 6 shows how the dewatered ice-slurry adheres to the surface of the chicken and melts slowly and thereby cooling the surface of the carcass, as monitored by heat sensitive camera. The bar on the bottom shows the color code scale of the temperature reading. Figure 7 shows the cooling efficiency when dewatered ice-slurry of the invention is used for cooling a whole chicken as shown in Figure 5, compared to conventional cooling by a combined cold blast air and cold water spray. The figure shows a temperature tracing of the internal temperature in the breast of the chickens shown in figure 5 when treated with dewatered ice-slurry of the invention. A similar temperature tracing is shown for a chicken carcass when cooled by the traditional method of the commercial settings using cold air blowing and cold water spraying. Figure 8 shows the cooling efficiency when dewatered ice-slurry of the invention is used for cooling a part of a fish as compared to conventional cooling by spraying with cold water or by soaking into a tank with normal ice-slurry. DETAILED DESCRIPTION OF THE INVENTION

As described herein, the invention is used to separate ice and liquid from an ice-slurry in an efficient and continuous way and thereby delivering the so produced dewatered ice- slurry for use in rapid chilling of perishable products, such as meat and fish. The invention can also be used for desalination and for concentration of solutes from polluted wastewater such as animal urine. The preferred embodiments of the invention adapted for continuously cooling food products, will now be described in details with reference to the drawings and figures provided. Unless defined otherwise, all technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, the preferred methods and materials are now described. EXAMPLE 1

This example shows drawings of the apparatus of the invention. Figure 1 shows a transection through the prototype version of the invention according to transect A- A in figure 2. The function of the individual parts as numbered in the drawings in figures 1 to 5 are explained according to the following list:

1. Intake tube for suction/pumping of ice-slurry into first chamber

2. Back plate of the apparatus housing the inlet tubes for ice-slurry (1), pressure air (10) and drive shaft (13).

3. Middle plate of the apparatus, attached to and turned by the drive shaft and housing chambers that turn according to different operations to be performed. The middle plate is shown in turning and carrying the ice-slurry at different stages in Figure 3.

4. Front plate of the apparatus also shown in front view in Figure 2, and housing openings for attaching tubes for different functions, see 6, 7, 8 and 9 below.

5. Filter attached to the front plate (4) and positioned over the openings 6, 7 and 8.

6. Tube for suction/vacuum to take in the primary wet ice-slurry.

7. Tube for suction/vacuum to dewater ice-slurry according to the targeted consistency. 8. Tube for optional operations if needed, such as more suction/vacuum to further dewatering, or adding water to wash the ice-slurry or to increase the temperature of the ice-slurry, or adding brine with higher salt concentration to decrease the temperature of the ice-slurry.

9. Opening/tube for delivering or shooting the dewatered ice-slurry by pressured air onto the target. This can also be led by pipes to deliver the dewatered ice-slurry into other places, such as cavities as shown by no 14 in Figure 5.

10. Inlet tube for pressured air.

11. Coupling mechanism for connecting and controlling the rotating function from an electric or air driven motor ( 13) to the apparatus.

12. Motor driving the rotation.

13. Drive shaft connecting the motor to the dewatering apparatus.

14. A pipe to deliver the dewatered ice-slurry into other places, such as carcass cavities. EXAMPLE 2

This example demonstrates the use of the invention for cooling chicken carcass on a conveyer belt. Figure 4 shows a drawing with a schematic view of the operation and how the dewatered ice-slurry can be delivered to different places and cavities of a chicken carcass where it adheres and melts slowly and thereby cooling the carcass.

In this example most of the experiments were done by using ice-slurry with about 25% ice and made from a salt solution containing 3.5-7% NaCl. Test have also been successfully done with rather wet ice-slurry of about 5% ice to about 85% ice, and also with nearly saturated NaCl solution, with temperatures as low as -15°C. The dewatered ice-slurry as produced by the invention can deliver ice-slurry over a wide range of ice content, or from 5% to at least 90% ice and at temperatures from about 0.5°C to about -15°C. EXAMPLE 3

This example demonstrates the use of the invention for cooling a part of a fish with dewatered ice-slurry, after the fish had been cut and was traveling along a conveyor belt in a commercial fish processing factory. Enough dewatered ice-slurry was delivered on top of the fish part to cover about 80% of the fish part with about 5 mm layer of ice-slurry of the invention. The ambient temperature in the factory was about 9°C when the experiment was done. At the same time fish parts were also cooled with two types of traditional cooling methods, i.e. spraying with about 5 liters of cold water with 0.2% salt in order to reach 0°C and immersing the fish part into a plastic box with wet ice-slurry as produced before dewatering and as normally used in the factory. The measurements were done using the parts of fresh cod cut from the same section of the cod in all cases and ranging from 270 grams to 310 grams. The temperature was measured in the core muscle of the fish using calibrated thermometers. Figure 8 shows temperature tracings of the internal temperature in the fish parts when comparing the use of dewatered ice-slurry of the invention and two traditional methods. It should be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the present invention and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the appended claims.