Method for producing frozen products

Abstract

The present invention provides a method for producing frozen gas hydrates, the method comprising passing a liquid aqueous phase through a heat exchanger surface under an atmosphere of a pressurized water-soluble gas, characterized in that the conditions of the method are selected to ensure that there is both dissolution of the pressurized gas in the liquid aqueous phase and formation of a solidified continuous phase from solidification of the liquid aqueous phase in contact with the surface of the heat exchanger.

Description

[0001] This application is a divisional application of Chinese Patent Application No. 201680069996.9, filed on November 22, 2016, entitled "Method of Production of Frozen Products". TECHNICAL FIELD

[0002] The present invention relates to a method of production of gas hydrates, the method comprising passing a liquid water phase over a heat exchanger surface, for use in a food product. BACKGROUND

[0003] Fizzy particles are desirable in many products, including children's products. In the field of frozen confectionery, gas hydrate crystals trapped within an ice structure can be used to deliver a fizzing sensation to the product. Gas hydrates (also known as clathrates) are crystalline solids composed of gas molecules surrounded by a cage of water molecules. It is thus similar to ice containing gas molecules within the water molecule cage. Gases whose molecular size is suitable for forming hydrates include carbon dioxide (CO2) and nitrous oxide (N2O). Suitable temperature and pressure conditions for forming carbon dioxide or nitrous oxide gas hydrates can be derived from the phase diagrams of the respective gas-aqueous liquid combinations, which can be found in the literature. Gas hydrates have a stoichiometric formula: for carbon dioxide gas hydrates, the theoretical maximum is CO2•5.75H2O. However, gas hydrate crystals are unstable at atmospheric pressure (even at typical freezer temperatures), so the hydrate crystals must be surrounded by ice to prevent hydrate decomposition during production and storage. The ice acts as a microscopic pressure vessel, and when warmed (for example, in the mouth when consumed), the ice layer surrounding the gas hydrate crystals melts and the gas hydrate decomposes, releasing gas. This provides a "fizzy" sensation similar to a carbonated beverage.

[0004] Carbon dioxide gas hydrates can be produced by passing carbonated water under pressure through a tube heat exchanger. As the carbonated water passes through, it freezes on the inner surface of the tube. As more carbonated water passes through the tube, it freezes on the ice already formed, gradually forming a tube of ice containing gas hydrates. The ice is then removed and broken up into particles. When consumed, these particles melt in the mouth, the gas hydrates release CO2 and provide a fizzing sensation. However, such techniques suffer from problems. For example, the activity of the particles (i.e. the amount of gas contained therein) can decrease along the length of the tube, as the water travels further along the tube, less CO2 is contained.

[0005] Methods of injecting gas into a mixture also suffer from problems. This is again due to the fact that the gas is utilised at the point of injection, and the mixture experiences a reduction in gas concentration as it travels further away from the point of injection. Such techniques disclosed in the prior art are as follows.

[0006] CA1225863 (PROCESS FOR PREPARING A GASIFIED ICE PRODUCT) discloses a process comprising: providing a source of liquid water at a temperature below about 5°C; providing a source of conditionally stable gas hydrate-forming gas at a temperature of about 5 to 10°C; dispersing the gas into the water at a gas to water weight ratio of about 0.10 to about 0.25 to provide a process feed stream; introducing the process feed stream into a dynamic reaction zone at a temperature within about 1°C of the hydrate formation equilibrium temperature at a preselected process pressure, said process pressure being in the range of about 300 to about 450 psig, and being maintained within the dynamic reaction zone; maintaining the gas and water in contact under dynamic conditions for a period of time effective to form conditionally stable gas hydrates and to dissolve the gas in the water to an extent effective to provide a uniform, flowable suspension of solid, gas hydrate, crystalline particles in a saturated carbon dioxide aqueous solution; conveying the suspension to a pressurized freezing vessel in communication with the dynamic reaction zone and a pressure control device comprising valve means and means for separating occluded gas from liquid and solid components, said pressure control device being capable of controlling system pressure to within 5 psig of a preselected pressure, closing the freezing chamber; and freezing the suspension under pressure.

[0007] US5231851 (METHOD AND DEVICE FOR CARBONATING AND COOLING A LIQUID (POST MIX EQUIPMENT AB)) relates to a method for carbonating and cooling a liquid, in particular a beverage, in which carbon dioxide is introduced under high pressure below the liquid surface and is allowed to expand and dissolve in the liquid. The invention also relates to a device for carrying out the method, which device comprises a closed container, a liquid inlet to the container, a carbon dioxide inlet to the container below the liquid surface, a carbonated liquid discharge conduit and a recirculation conduit for carbon dioxide not dissolved in the liquid leading from above the liquid surface in the container. The carbon dioxide is introduced below the liquid surface. Thus, the liquid is carbonated before it is cooled. Furthermore, it is claimed that the device is suitable for preparing ice-cold carbonated beverages at home, in the office, etc., without involving freezing and without being suitable for producing carbonated water ice granules.

[0008] US4393660 (QUIESCENT FORMATION OF GASIFIED ICE PRODUCT AND PROCESS (GENERAL FOODS)) discloses a method for preparing vaporized ice cream characterized by a granular crystalline porous structure, a brittle texture, good stability in the frozen state, and the ability to rapidly and quietly release gas upon melting in an aqueous solution. Improved products with these characteristics are also provided. The method includes: maintaining an aqueous liquid in a pressurized container at temperature and pressure conditions that effectively form a stable gas hydrate when in contact with a conditionally stable hydrate-forming gas; introducing finely dispersed bubbles of the conditionally stable hydrate-forming gas into the aqueous liquid at a pressure higher than the pressure inside the container to bring the liquid into contact with the gas; continuously extracting gas from the container to maintain a substantially constant pressure inside the container and a substantially constant flow rate through the container; maintaining the contact for a period of time to effectively form a suspension containing a gas hydrate dispersed in the liquid; and freezing the suspension under pressure.

[0009] US2575509 (ICE PRODUCT AND METHOD OF MANUFACTURING (ICECRAFTERTRUST)) relates to ice products and methods for producing such products. In the production of carbonated ice or ice filled with other gases, switches are installed at specific locations to create a closed loop, allowing valves to be opened and closed. Water is then supplied to the freezing unit from a carbonator, and charging gas is delivered by a cylinder, causing the ice to freeze under high pressure and in the presence of gas. The valve operation sequence is as follows: the motor is first energized, moving a plate to its closed position to seal the bottom of the freezing unit. The solenoid valve is closed, and water is forced under pressure through the water supply line, pipeline, carbonator, pipeline, and opening valve into the freezing unit until the pressure of trapped air in each chamber equals the pressure of the incoming water, thereby regulating the water level in the chambers. The aerated water is then frozen.

[0010] GB2425165 (MAKING FROZEN CARBONATED BEVERAGES (IMI VISION LTD)) discloses a method for producing frozen carbonated beverages. This disclosure... Figure 1A simplified diagram of a machine for producing frozen carbonated beverages is shown, in which CO2 from a CO2 source is supplied to the compressor inlet via a valve. The CO2 is discharged from the compressor at a pressure of 60-120 bar and a temperature of approximately 180°C. It then passes through a condenser, which cools the CO2 to approximately ambient temperature plus 5°C, after which it enters a carbonator containing the beverage through a conduit. The conduit terminates at a nozzle immersed in the beverage.

[0011] US4022119 (LIQUID CARBON DIOXIDE CARBONATION APPARATUS (GENZYME CORPCONS FOODS CORP; SHASTA BEVERAGES)) discloses a method and apparatus for simultaneously carbonating and cooling liquids such as carbonated beverages. Carbon dioxide is injected in liquid form into the bottom of a liquid carbonation column. The liquid flows upward through the column and then through the top into an annular channel surrounding the column to exit from a container.

[0012] JP2012191935 (ICE CREAM CONTAINING CARBON DIOXIDE GAS, AND METHOD FOR PRODUCING THE SAME (LOTTE)) discloses a method for producing ice cream containing carbon dioxide gas, the method comprising: (a) freezing an ice cream mixture or frozen dessert liquid mixture obtained by maturing at least one raw material selected from milk and skim milk and injecting carbon dioxide gas into the frozen mixture; and (b) filling the ice cream mixture or frozen dessert liquid mixture containing carbon dioxide gas into a container to produce ice cream containing carbon dioxide gas.

[0013] Alternatively, after step (a) of freezing an ice cream mixture or frozen dessert liquid mixture obtained by maturing at least one ingredient selected from milk and skim milk, the step of injecting carbon dioxide gas into a gas mixer is performed before the step of filling the container is performed (b).

[0014] Similar techniques disclosed in the prior art involve introducing gas into a mixture. However, such methods also have problems because the gas concentration in the mixture decreases at locations far from the gas introduction point. Examples of such techniques disclosed in the prior art are as follows.

[0015] EP1328162 (CARBON DIOXIDE-HYDRATE PRODUCT AND METHOD OF MANUFACTURETHEREOF) discloses a method for producing frozen carbonated desserts, which are claimed to exhibit high CO2 retention without significant dry ice formation and can be stored stably in a household refrigerator environment. According to a preferred method for implementing the invention, water is introduced into a reactor under ambient pressure and purged with an inert gas. After purging, the water is cooled to just above freezing. The cooling water is stirred, and carbon dioxide is introduced into the reactor under pressure (preferably about 400 psig), where a CO2 hydration reaction is carried out with continuous stirring for about 30 minutes. The reaction mixture is then cooled to about -5°F, producing a product containing solid CO2 hydrates, which is then ground to an acceptable particle size.

[0016] WO9618310 (PROCESS TO PRODUCE CARBONATED SEMI-SOLID OR SOLID FOOD AND THE PRODUCT THEREOF (BRIGHAM YOUNG UNIV)) relates to a carbonated semi-solid spoonable food having the following properties: (a) a viscosity of about 2,000 to 200,000 centipoise (cp) at about 1.5 to 25°C; and (b) a carbonation level of about 0.5 to 4.0 volumes of carbon dioxide. Preferred foods include yogurt, pudding, gelatin, custard, ice cream mixtures, etc. Fermented yogurt is more preferred. The food is optionally packaged in a conventional food container with a sealing device to seal the carbon dioxide. Another embodiment is a method for producing a carbonated, thickened, semi-solid, spoonable food, the method comprising: contacting the food with carbon dioxide gas at a temperature of about 8 to 25°C and a carbon dioxide pressure of about 0 to 110 psig for 1 to 180 minutes under low-shear stirring; to produce a carbonated, semi-solid, thickened food having (a) a viscosity of about 3,000 to 180,000 at a temperature of about 10 to 25°C, and (b) a carbonation level of about 0.5 to 4.0 volumetric carbon dioxide.

[0017] GB1005399 (METHOD OF ENHANCING THE FLAVOUR OF DAIRY DESSERT (AMERICANMACH AND FOUNDRY)) discloses the following discovery: incorporating a certain critical amount of carbon dioxide into desserts produces frozen desserts with desired characteristics. This disclosure specifically mentions dairy desserts that are typically consumed in a semi-frozen state.

[0018] EP0965563 (MANUFACTURE OF EDIBLE FROZEN PRODUCTS) provides a method for producing gaseous hydrates, the method comprising the steps of: (i) filling a container with a quantity of liquid water and / or chilled water; (ii) adding a quantity of condensate-forming gas to the container in a manner such that the condensate gas does not come into contact with the liquid water; and (iii) contacting the condensate gas and / or its sublimation or liquefaction products with the mixture of liquid water and / or chilled water at a suitable pressure to produce a reaction mixture, and maintaining the reaction mixture at or below a maximum temperature and suitable pressure that would stabilize the gaseous hydrates for a sufficient time to produce gaseous hydrates.

[0019] Other prior art disclosures using pre-seeding, such as US4934153 (METHOD FORMANUFACTURING ICE CONTAINING CARBON DIOXIDE (NIPPON KOKAN KK)), disclose a method for producing ice containing carbon dioxide, which includes loading ice pellets or water as feedstock into a pressure vessel; encapsulating the feedstock in a carbon dioxide atmosphere; and adjusting the temperature and pressure of the feedstock such that the temperature and pressure are values ​​within a range defined by a straight line connecting specific points on a temperature-pressure graph.

[0020] Flash freezing is another method, as described in the journal article "Production of CO2 clathrate hydrate frozen desserts by flash freezing" (Peters, TB; Smith, JL; Brisson, J. G - Journal of Food Engineering (2010), Volume 100, Number 4, pp. 669-677), which discloses the development of a CO2 flash freezing method for forming CO2 hydrates during the freezing process of dessert mixtures. In this method, liquid CO2 and a liquid dessert mixture are emulsified and then sprayed into a chamber where the CO2 flashes into vapor, freezing the dessert mixture into a low-density powder.

[0021] However, pre-catalysis and flash freezing techniques are relatively complex methods and may not be suitable for the industrial-scale production of gas hydrates.

[0022] Finally, other methods may utilize pressure contact between the gas to be dissolved and the solution. These methods are as follows.

[0023] WO9716980 (PROCESS FOR THE PREPARATION OF AN ICE CONFECTION (UNILEVER)) discloses in Example 2 the production of particles containing a CO2-water inclusion complex as follows: CO2 and water are contacted in a pressure reactor at a pressure of 35 bar and a temperature of 5°C; then the temperature is lowered to -15°C to solidify the carbonic acid complex; after being removed from the reactor, the resulting inclusion complex-ice complex is ground in a grinder to a particle size of 50-200 mm at -20°C.

[0024] US20099266106 (METHOD AND APPARATUS FOR PRODUCING CLATHRATE HYDRATESLURRY, AND METHOD FOR OPERATING THE SAME APPARATUS) discloses a method for producing cage hydrate slurries, the method comprising the steps of: injecting an aqueous solution of a cage hydrate guest compound or a slurry of cage hydrate dispersed or suspended in an aqueous solution or water into a heat transfer tube, and exchanging heat between the aqueous solution or slurry and a refrigerant present on the outer periphery of the heat transfer tube, thereby producing cage hydrates in the aqueous solution or slurry, characterized in that, during the heat exchange with the refrigerant, the increase in the amount of cage hydrate deposited on the inner wall surface of the heat transfer tube is suppressed by the hydrodynamic force of the aqueous solution or slurry flowing within the heat transfer tube.

[0025] US4333315 (PROCESS FOR PREPARING A GASIFIED ICE PRODUCT) discloses a method comprising: contacting an aqueous liquid with a conditionally stable hydrate in a closed pressure vessel under pressure and temperature conditions for effective formation of a gas hydrate; vigorously agitating the aqueous liquid during the contact to disperse gas bubbles in the gas during continuous and effective mass transfer contact; maintaining the contact for a period of time to effectively form a suspension containing a gas hydrate dispersed in the aqueous liquid; degassing the suspension by gentle agitation to expel unreacted and undissolved gas bubbles from the suspension and allow them to rise to their upper surface; transporting the suspension under pressure through a port in the vessel to a pressurized freezing chamber; and freezing the substantially bubble-free suspension under pressure.

[0026] WO10069769 (METHOD FOR PRODUCING AN EDIBLE GAS HYDRATE) provides a method for producing an edible complex of gas hydrates and ice using an extruder, the extruder including a barrel having an inlet and an outlet and having a cooling device, the method comprising: (a) feeding an aqueous gas solution through the inlet into the barrel of the extruder under high pressure; (b) cooling the barrel to form a frozen plug within the extruder, thereby bringing the pressure within the barrel to or above the minimum pressure required to form the gas hydrate; (c) freezing the gas solution within the barrel to form the complex; and (d) extruding the frozen complex from the extruder outlet.

[0027] GB 1095004 and US 3220204 disclose apparatus for forming CO2 gaseous hydrates in water by passing water through a pipe under a pressurized CO2 atmosphere. To facilitate the removal of the material from the pipe, care must be taken to ensure that freezing does not occur within the pipe, allowing the liquid water carrying the gaseous hydrates to exit. Subsequent freezing steps are then performed.

[0028] However, none of these methods adequately address the problem of uneven or reduced particle activity in the reaction vessel.

[0029] Therefore, there is still a need for methods that can overcome these problems and provide industrially applicable, effective methods that can be used on a large scale to produce highly active gaseous hydrates with consistent activity (i.e., consistent amounts of gas they contain) and that can be released when consumed by consumers.

[0030] As described below, the present invention provides a method that satisfies all of these requirements. Summary of the Invention

[0031] We have now discovered a specific method to solve the above-mentioned problems. Specifically, the method of the present invention does not require the use of pre-carbonated or previously formed aqueous gas solutions. Instead, a liquid aqueous phase flows through a heat exchange surface in a thin layer under an atmosphere of water-soluble pressurized gas. The gas typically enters the solution along the entire heat exchange surface, and gas hydrates are always formed along and across the entire heat exchange surface. Therefore, the subsequently generated gas hydrate / water ice particles do not have the problem of uneven or reduced activity on the heat exchange surface. "Activity" refers to the gas volume per unit mass of particles at room temperature, typically measured in ml / g.

[0032] This invention relates to a method for producing refrigerated gas hydrates, the method comprising passing a liquid aqueous phase through a heat exchanger surface under an atmosphere of pressurized water-soluble gas, characterized in that the conditions of the method are selected to ensure that the pressurized gas is dissolved in the liquid aqueous phase and that a solidified continuous phase is formed by the solidification of the liquid aqueous phase in contact with the heat exchanger surface.

[0033] Therefore, the present invention provides gas dissolution, gas hydrate formation, and liquid phase freezing in a single method step. Thus, this method is more efficient and convenient than prior art methods.

[0034] Liquid water phase can be allowed to flow, for example, through a heat exchange surface.

[0035] Preferably, the thickness of the liquid aqueous phase is no more than 0.5 cm, as this facilitates the diffusion of water-soluble gases into the aqueous phase and towards the heat exchange surface. Preferably, the aqueous phase is in a layer with a thickness of at least 0.005 cm, more preferably at least 0.01 cm, even more preferably at least 0.02 cm, even more preferably at least 0.03 cm, still more preferably at least 0.04 cm, even more preferably at least 0.05 cm, and even more preferably at least 0.06 cm.

[0036] Preferably, the heat exchange surface is at a temperature of at least -30°C, more preferably at least -25°C, even more preferably at least -20°C, even more preferably at least -18°C, even more preferably at least -16°C, even more preferably at least -14°C, more preferably at least -12°C, even more preferably at least -11°C, and most preferably at least -10°C.

[0037] Preferably, the heat exchange surface is at a temperature of at most 0°C, more preferably at most -1°C, even more preferably at most -2°C, even more preferably at most -3°C, still more preferably at most -4°C, even more preferably at most -5°C, even more preferably at most -6°C, even more preferably at most -7°C, and most preferably at most -8°C.

[0038] Preferably, the pressure of the water-soluble gas is constant on the heat exchange surface.

[0039] Preferably, the method is carried out under a pressure of at least 1000 kPa, more preferably at least 1500 kPa, even more preferably at least 1750 kPa, even more preferably at least 2000 kPa, even more preferably at least 2100 kPa, even more preferably at least 2200 kPa, more preferably at least 2300 kPa, even more preferably at least 2400 kPa, and most preferably at least 2500 kPa.

[0040] Preferably, the pressure is up to 4000 kPa, more preferably up to 3750 kPa, even more preferably up to 3500 kPa, even more preferably up to 3250 kPa, even more preferably up to 3000 kPa, even more preferably up to 2750 kPa, even more preferably up to 2700 kPa, even more preferably up to 2650 kPa, and most preferably up to 2600 kPa.

[0041] Preferably, the aqueous phase is in a layer with a thickness of at most 0.40 cm, more preferably at most 0.25 cm, even more preferably at most 0.20 cm, even more preferably at most 0.15 cm, even more preferably at most 0.125 cm, even more preferably at most 0.10 cm, even more preferably at most 0.09 cm, and most preferably at most 0.08 cm.

[0042] Preferably, the liquid aqueous phase is introduced onto the surface of a heat exchanger that contains essentially no dissolved water-soluble gases. Thus, the water-soluble gases diffuse into the liquid aqueous phase and form gas hydrates in a single step.

[0043] Preferably, the gas is carbon dioxide.

[0044] Preferably, the method is an intermittent method, and the cured continuous phase increases in thickness until the desired thickness is achieved. The produced cured phase containing gas hydrates and / or chilled water can then be removed from the apparatus, and the method can be started again.

[0045] To facilitate the removal of the cured phase, the preferred method subsequently involves heating the heat exchanger surface to melt the cured continuous phase in contact with the heat exchanger surface, thereby promoting the removal of the cured continuous phase from the heat exchanger surface.

[0046] Preferably, the surface of the heat exchanger is the interior of a tubular pipe.

[0047] In the preferred arrangement, the method conditions are such that a portion of the liquid water phase remains liquid after passing through and leaving the heat exchanger surface.

[0048] Preferably, the liquid leaving the heat exchange surface is recirculated to reintroduce the liquid to the heat exchange surface. Preferably, the liquid is heated before reintroducing it to the heat exchange surface to ensure that it is free of any gas hydrates.

[0049] Preferably, the frozen product formed by this method is pulverized to form ice particles containing gas hydrates. Detailed Implementation

[0050] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art (e.g., in the field of frozen confectionery production). For definitions and descriptions of various terms and techniques used in frozen confectionery production, see Ice Cream, 6th Edition, Robert T. Marshall, H. Douglas Goff, and Richard W. Hartel (2003), Kruwell Academic / Conference Press. Unless otherwise stated, all percentages refer to weight percentages of frozen desserts.

[0051] "Thickness" refers to the average thickness of a layer as measured by taking a point on one surface or side of the layer, measuring the minimum distance from that point to the other surface or side of the layer, repeating these measurements N times, and then dividing the sum of the N minimum distances by N, for example, measuring ten times at intervals along the heat exchange surface.

[0052] The complex of gas hydrates and ice consists of gas hydrate crystals trapped within an ice structure. Gas hydrates are crystalline solids composed of gas molecules surrounded by cages of water molecules. Therefore, they are similar to ice, except that the crystal structure has guest gas molecules within the water molecule cages. Many gases have molecular sizes suitable for forming hydrates, including carbon dioxide (CO2) and nitrous oxide (N2O). In the context of this invention, gases comprising or composed of carbon dioxide and / or nitrous oxide are preferred.

[0053] Suitable temperature and pressure conditions for the formation of carbon dioxide or nitrous oxide gas hydrates can be derived from phase diagrams of the corresponding gas-aqueous liquid combinations, which can be found in the literature. For example, Figure 1 The phase diagram of carbon dioxide gas hydrate is given in the figure.

[0054] Gas hydrates have a stoichiometric molecular formula: for carbon dioxide gas hydrate, the theoretical maximum is CO2•5.75H2O. However, gas hydrate crystals are unstable under atmospheric pressure (even at typical cold storage temperatures). Therefore, when preparing gas hydrates for frozen desserts, an excess of water (i.e., more water than the stoichiometric ratio is specified) is typically used, resulting in a complex of gas hydrate crystals in ice. Ice surrounding the hydrate crystals is necessary to prevent decomposition of the hydrates during production and storage. In effect, the ice acts as a microscopic pressure vessel. When heated (e.g., in the mouth when consumed), the ice surrounding the gas hydrate crystals melts, and the gas hydrates decompose, releasing gas. This provides a "bubbly" sensation similar to carbonated drinks.

[0055] The applicant has sought to design an improved method for preparing gas hydrates. We have found that gas hydrates readily form in a consistent manner and exhibit high reactivity when a thin layer of liquid aqueous phase is passed through a heat exchange surface (e.g., flowed over the surface) under a pressurized gas atmosphere.

[0056] In its simplest product form, the aqueous phase can consist essentially of water alone, such that the final product consists essentially of ice and gas hydrates. However, one or more optional other components may be added to the aqueous phase; and / or aggregated with the gas feed; and / or introduced as one or more separate product streams. Preferably, the aqueous phase contains at least 90%, more preferably at least 95%, and most preferably at least 99% water by weight prior to gas dissolution.

[0057] The aqueous phase may also contain one or more sweeteners. Since sweeteners provide sweetness and control ice content by lowering the freezing point, they are standard ingredients in frozen desserts. Therefore, the aqueous phase preferably contains at least 0.01%, more preferably at least 0.1%, more preferably at least 0.2%, but more preferably at most 20%, more preferably less than 10%, even more preferably less than 5%, and most preferably less than 1% by weight of one or more sweeteners. Sweeteners include monosaccharides and disaccharides such as dextrose, fructose, sucrose, and lactose; oligosaccharides containing 3 to 10 monosaccharide units linked by glycosidic bonds; corn syrup and maltodextrin; and sugar alcohols (also known as polyols or polyhydroxy alcohols), such as erythritol, arabinitol, glycerol, xylitol, sorbitol, mannitol, lactitol, maltitol, hydrogenated starch hydrolysate (HSH) – also known as polyols, isomaltitol, and paraginitol.

[0058] Optionally, the aqueous phase may also contain other ingredients commonly used in frozen desserts, such as stabilizers, colorings, and flavorings.

[0059] To ensure the formation of gas hydrates in the method, the heat exchange surface is preferably at a temperature of at least -30°C, more preferably at least -25°C, even more preferably at least -20°C, even more preferably at least -18°C, still more preferably at least -16°C, even more preferably at least -14°C, more preferably at least -12°C, even more preferably at least -11°C, and most preferably at least -10°C. Preferably, the heat exchange surface is at a temperature of at most 0°C, more preferably at most -1°C, even more preferably at most -2°C, even more preferably at most -3°C, even more preferably at most -4°C, even more preferably at most -5°C, more preferably at most -6°C, even more preferably at most -7°C, and most preferably at most -8°C.

[0060] It has been found that the method of the present invention operates optimally within the pressure range of the gas to be incorporated into the hydrate. "Pressure" refers to partial pressure, i.e., the pressure exerted by the gas on the gas mixture. The method is preferably carried out at a pressure of at least 1000 kPa, more preferably at least 1500 kPa, even more preferably at least 1750 kPa, even more preferably at least 2000 kPa, even more preferably at least 2100 kPa, even more preferably at least 2200 kPa, even more preferably at least 2300 kPa, even more preferably at least 2400 kPa, and most preferably at least 2500 kPa. Preferably, the pressure is at most 4000 kPa, more preferably at most 3750 kPa, even more preferably at most 3500 kPa, even more preferably at most 3250 kPa, even more preferably at most 3000 kPa, even more preferably at most 2750 kPa, even more preferably at most 2700 kPa, even more preferably at most 2650 kPa, and most preferably at most 2600 kPa.

[0061] To allow the dissolved gas to reach the freezing interface between the liquid aqueous phase and the heat exchange surface, the liquid aqueous phase is preferably in a layer with a thickness of at most 0.40 cm, more preferably at most 0.25 cm, even more preferably at most 0.20 cm, even more preferably at most 0.15 cm, even more preferably at most 0.125 cm, even more preferably at most 0.10 cm, even more preferably at most 0.09 cm, and most preferably at most 0.08 cm. Preferably, the liquid aqueous phase is in a layer with a thickness of at least 0.005 cm, more preferably at least 0.01 cm, even more preferably at least 0.02 cm, even more preferably at least 0.03 cm, even more preferably at least 0.04 cm, even more preferably at least 0.05 cm, and even more preferably at least 0.06 cm.

[0062] As the liquid aqueous phase passes through the heat exchange surface, it freezes, creating a frozen layer containing gas hydrates. This frozen layer initially accumulates on the heat exchange surface, but as the method continues, it becomes clear that the frozen layer will cover the heat exchange surface. When this occurs, the interface between the frozen layer and the liquid aqueous phase acts as the heat exchange surface, through which the liquid aqueous phase continues to pass, freezing and further generating gas hydrates. The heat exchange surface can be flat, wavy, bladed, or convexly or concavely curved. Preferably, the heat exchange surface forms a closed conduit through which the liquid aqueous phase passes, and thus the gas hydrates form within the conduit as conduits. The thickness of the frozen layer containing gas hydrates (when the gas hydrates are removed from the apparatus) is preferably at least 0.1 cm, more preferably at least 0.25 cm, even more preferably at least 0.5 cm, still more preferably at least 0.6 cm, even more preferably at least 0.7 cm, even more preferably at least 0.8 cm, even more preferably at least 0.9 cm. The thickness of the frozen layer containing gas hydrates is preferably at most 4 cm, more preferably at most 2 cm, more preferably at most 1.9 cm, even more preferably at most 1.75 cm, still more preferably at most 1.6 cm, even more preferably at most 1.5 cm, even more preferably at most 1.4 cm, even more preferably at most 1.3 cm, even more preferably at most 1.2 cm, and even more preferably at most 1.1 cm. Most preferably, the thickness of the frozen layer containing gas hydrates is 1 cm.

[0063] The material formed by this method is in the form of a solid gas hydrate or a complex of gas hydrate and ice with a high hydrate content. This material is typically intended as an additive in frozen desserts to create a foamy texture in the mouth. Therefore, after production, the material is usually crushed, cut, or pulverized into small pieces of any desired size (e.g., about 1-5 mm). These small pieces can be packaged directly, or they can be mixed with sauces or incorporated into frozen desserts such as ice cream, sorbets, or water ice to form the final product.

[0064] The term "frozen dessert" refers to prepared foods intended for consumption in a frozen state (i.e., at a temperature below 0°C, and preferably containing a large amount of ice). Frozen desserts include ice cream, sorbets, fruit sorbets, frozen yogurt, water ice, and milk ice. Frozen desserts such as ice cream and frozen yogurt typically contain fat, protein (such as milk protein), and sugar, along with other additives such as stabilizers, emulsifiers, colorings, and flavorings. Water ice, by weight of the composition, typically contains 15-25% sugar along with stabilizers, colorings, and flavorings.

[0065] Typically, other ingredients are combined to produce frozen desserts (e.g., ice cream) or sauces / syrups in which gas hydrates / ice are mixed. Preferably, the edible gas hydrate / ice complex comprises 5-50% by weight of the total frozen dessert, more preferably 10-20% by weight. After the gas hydrate / ice complex is combined with other ingredients, the frozen dessert can undergo another freezing step (e.g., hardening) and can then be packaged.

[0066] The invention will now be explained in more detail through the following description of preferred embodiments and with reference to the accompanying drawings.

[0067] Except in the operating and control examples, all figures in the instruction manual indicating the amount of material, reaction conditions, physical properties of the material and / or uses should be understood as being preceded by the word "about".

[0068] When numerical values ​​serve as upper and / or lower limits and / or preferred restrictions, all restrictions can be combined to describe the preferred range.

[0069] The invention will now be described with reference to the following figures, in which: Figure 1 Show the phase diagram of the carbon dioxide / ice inclusion complex.

[0070] Figure 2 This diagram shows a flowchart of a pilot-scale gas hydration machine used to carry out the method of the present invention.

[0071] Figure 3 This displays a comparison between the calculated and measured data from the production model.

[0072] Figure 4 The display parameters show the absolute impact on output.

[0073] Figure 5 This demonstrates the impact of pressure and speed on output.

[0074] Figure 6 This shows the impact of tank pressure and filling on production.

[0075] Figure 7 This shows a comparison between the calculated and measured data of the activity model.

[0076] Figure 8 This shows the effect of pressure, speed, and filling on the measured activity.

[0077] Figure 9 The results show that increased production leads to increased activity.

[0078] Example Machine assembly and working principle If possible Figure 2As seen, the preparation device 10 consists of three jacketed columns 12, 13, and 14, a jacketed water tank 16, an upper water tank 18, a circulating pump (centrifugal pump) 20, a feed tank 22, and a CO2 supply 24 with a regulator. Each jacketed column 12, 13, and 14 includes corresponding refrigeration pipes 12a, 13a, and 14a. The refrigeration pipes have an inner diameter of 22.4 mm and a length of 60 cm. The water tank has a volume of approximately 6 liters. The cooling medium used is a potassium formate solution, which is cooled / heated by a "Tricool" heater and cooler unit. The equipment is pressurized with CO2 24. Demineralized water is drawn from the water tank 16 into the upper water tank 18, and then allowed to flow back into the water tank 16 by gravity in a thin laminar flow along the column walls.

[0079] Water flows downwards in a thin layer from the interior of refrigeration pipes 12a, 13a, and 14a in the direction of arrow 26, and the interior portions of the pipes are dry to maintain the hollow central channel containing pressurized CO2 gas. The pipes are cooled as follows: coolant is drawn from the bottom to the top of columns 12, 13, and 14 outside the pipes in the direction of arrow 28 to cool the outer surfaces of pipes 12a, 13a, and 14a. Therefore, the heat exchange surface is the interior of pipes 12a, 13a, and 14a. Thus, countercurrent heat exchange occurs, accompanied by cooling and crystallization of the demineralized water inside the columns.

[0080] The method is arranged such that some water exits the column to ensure all heat exchange surfaces are submerged and to help ensure the cured layer increases evenly throughout the pipe. The water tank is heated sufficiently to eliminate any gas hydrates that form in the water entering the pipe, so that no gas hydrates are present in any circulating water entering the pipe.

[0081] Because of the applied CO2 pressure, instead of crystallizing into ice crystals, water encapsulates the CO2 molecules, forming hydrates. Furthermore, since the pressure is constant along the height of the column, the rate at which CO2 molecules are encapsulated by water is constant throughout the column. Hydrate formation is exothermic, and the generated heat is removed to allow for further crystallization. Hydrates accumulate from the surfaces of pipes 12a, 13a, and 14a towards the center, thus creating a hollow cylinder.

[0082] A heat exchange surface is provided at the interface between the chilled water containing gas hydrates and the water continuing to flow downwards in a thin layer, where gas hydrates continue to form. Due to countercurrent heat exchange, the resulting conduit is thicker at the bottom. After one cycle is completed, the circulation of demineralized water stops, the pressure is released, and the column is heated by a warmer liquid flowing through the jacket. The column is then opened at the bottom, and the conduit containing gas hydrates is released. The conduit is then crushed to form particles containing gas hydrates.

[0083] Physical / chemical processes During a process, the phase diagram is determined ( Figure 1 The "operating point" on the line. The applied pressure (e.g., 25 bar) is the first point, and the process must occur on the marked line when CO2 gas, liquid water, and inclusion compounds are present simultaneously.

[0084] During each process, the temperatures in the top chamber and the water tank were recorded. The development of each process was then monitored. Each process exhibited similar behavior: the temperature continuously decreased until a minimum was reached. Crystallization began at this minimum temperature because hydrate formation is exothermic, after which the temperature rose. The temperature continued to rise until it reached an equilibrium temperature dependent on the pressure. In this context, equilibrium refers to the process where new crystals occur and release heat on one hand, while on the other hand, heat is removed by a cooling device.

[0085] Procedure during the experiment Demineralized water is filled into the tank using a circulation pump with the valve set to the fill position. When the tank is approximately 50% full, the valve is switched to the "circulate" position. The system is then pressurized to the desired pressure by opening the gas supply, and the pump is started to begin circulating the demineralized water. After 1 minute, the cooling system is opened, and coolant at approximately -20°C flows from the bottom to the top of the column jacket. After a few minutes, gas hydrates begin to accumulate. After approximately 25 minutes of operation, the pump is stopped, and the pressure is released through the tank. The column is opened at the bottom, and the jacket is flushed with a warmer liquid (approximately 7°C). The pipes melt after 2 minutes of heating.

[0086] Experimental design Create an experimental design to study the parameters of "pressure", "pumping speed", and "water volume in the tank". For each parameter, determine low, medium, and high levels. Use pressures of 18, 25, and 32 bar. Set the pumping speed using a rotary switch at 35, 40, and 45 Hz. Fill the tanks to volumes of 2.9 liters, 4.0 liters, and 5.2 liters.

[0087] Some combinations did not operate correctly. For example, an experiment using 32 bar and a low water volume failed after a short run because all the water crystallized and the pump ran dry. Another combination at 18 bar did not work because the level sensor in the top tank started flashing and the pump stopped running.

[0088] Each combination of processes is run at least four times. Since the first process always exhibits slightly different behavior, its result is always excluded. In some cases, if the result is problematic or an unexpected event occurs, the process is repeated more times. Only the result of the process without objections is considered.

[0089] For each experiment, the quantity (yield) of product was weighed. The bottom portion of each gas hydrate tube was individually packaged in a plastic bag and immediately placed in a freezer at -25°C. After one day of storage, a piece of gas hydrate was removed and its activity was measured.

[0090] Statistical analysis of the experimental data (i.e., the results of weight / yield determination and activity measurement) revealed the interactions between the parameters. Multiple regression was applied.

[0091] Model for yield A model is used to calculate the effect of the descriptive parameter on the output variable (i.e., yield). The model has been found to be of good quality, with a coefficient of determination (R²) of [value missing]. 2 The value for repeatability (W) was 97%. 2 This achieved a relatively high value of 98%. Figure 3 The comparison between the calculated and measured values ​​(of production) can be seen in the table.

[0092] Statistically, all three parameters were highly significant (P < 1%). The parameter showing the greatest impact on yield was pressure. Figure 4 By increasing the pressure from 18 bar to 25 bar, the yield per process increased from approximately 405 g to 580 g (with other parameters at intermediate settings). In contrast, pumping speed and tank filling level showed relatively low absolute impact. The effect of pump speed was inversely proportional: the faster the pump ran, the lower the yield. The yield decreased from 535 g to 450 g. Increasing the water volume in the tank had a positive impact on the yield: by increasing the water volume, the yield increased from 455 g to 530 g.

[0093] The effects of speed and fill are only noticeable at 18 bar, as can be seen at other times. Figure 5 and Figure 6 As seen in the example, simply reducing the pump speed (at a pressure of 18 bar and a tank capacity of 4.0 liters) increased the output from 320 g to 460 g. On the other hand, at 25 bar, changing the speed only slightly altered the output.

[0094] The effect of filling can be explained by using a constant tank jacket temperature in the experiments. After a certain operating time, each process equilibrates to a specific temperature, depending on the applied pressure. For 25 bar, this is approximately 6°C, while at 18 bar, it is approximately 4°C. The tank is jacketed and heated to prevent freezing. For all tests, this temperature was set to 6°C. At 25 bar, this temperature is not detrimental to the crystallization process because it is close to the equilibrium temperature. At 18 bar, the tank heating raises the overall system temperature and inhibits some molecular crystallization. With a high water volume in the tank, this heating effect is less pronounced because the wall surface area / water volume ratio decreases. The increased yield at higher pressures can be explained by increased heat transfer: since the temperature (from the operating point on the phase diagram) is higher at 25 bar than at 18 bar, the temperature gradient between the cooling walls and the surrounding water is greater, therefore, the formula Q̇ = k*A* Q in T is higher compared to 18 bar.

[0095] Model for activity Samples were taken from the bottom of the gas hydrate conduit. The thicker section at the bottom was mostly filled with a gray material, which was considered to be a high percentage of hydrate material. Although this method helps reduce the variability of the measured activity, the raw data remain highly inconsistent, and therefore, the quality of the model ( Figure 7 This is not as good as the yield model. Only pressure has a highly significant effect on activity, while rate and filling have no significant effect. For example, it could be... Figure 8 As seen in the diagram, by increasing the pressure from 18 bar to 25 bar, the activity increased from approximately 35 ml / g to over 47 ml / g (however, the margin of error (95% probability of error) is quite large).

[0096] Relationship between yield and activity Under correct conditions, 100% pure hydrates with a maximum activity of 150 ml / g can be produced. Because a certain percentage decomposes as it melts from the column, the activity measured by this method decreases across the entire diameter. Therefore, the thicker the tube, the smaller the percentage of decomposed hydrates and the higher the average activity. The correlation between yield and activity was sought using experimental data. A computational model was developed with a correlation coefficient R of 78%. 2 The relatively low values ​​can be explained by the variability of activity values. Overall, as can be seen... Figure 9 As observed, low yield is associated with low activity below 30 ml / g, while increased yield helps achieve higher activity.

[0097] Summary A set of experiments was performed and analyzed to determine the effects of parameters (pressure, extraction rate, and water volume in the system) on the method and product. For each process, yield and activity were measured and a model was calculated. For yield, it can be shown that although pressure exhibits the greatest effect, extraction rate and water volume in the tank are also important, especially at low pressures (18 bar). Conversely, at 25 bar, these two parameters do not show a strong effect, and therefore, the method operates robustly regardless of other settings. For the activity model, only pressure has been shown to be important, with higher pressure correlated with higher activity.

Claims

1. A method for producing frozen gas hydrates, the method comprising passing a liquid water phase over the surface of a heat exchanger in an atmosphere of pressurized water-soluble gas, characterized in that the conditions of the method are selected to ensure that the pressurized gas is simultaneously dissolved in the liquid aqueous phase and a solidified continuous phase is formed from solidification of the liquid aqueous phase in contact with the heat exchanger surface, wherein the method is conducted at a pressure of 1000 kPa to 4000 kPa, wherein the method is a batch process and the solidified continuous phase is increased in thickness until a desired thickness is obtained, wherein the heat exchanger surface is at a temperature of -30°C to -8°C, wherein the conditions of the method are such that a portion of the liquid aqueous phase remains liquid after passing over and exiting the heat exchanger surface, and wherein the liquid exiting the heat exchanger surface is recirculated to introduce the liquid again to the heat exchanger surface.

2. The method of claim 1, wherein the thickness of the liquid aqueous phase is no greater than 0.5 cm.

3. The method of claim 1 or claim 2, wherein the pressure of the water soluble gas is constant over the heat exchanger surface.

4. The method of claim 1 or claim 2, wherein the gas is carbon dioxide, nitrous oxide or a mixture thereof.

5. The method of claim 1 or claim 2, wherein the liquid aqueous phase is introduced to the heat exchanger surface that is substantially free of dissolved water soluble gas.

6. The method of claim 1 or claim 2, which is followed by the step of warming the heat exchanger surface to melt the solidified continuous phase in contact with the heat exchanger surface to facilitate removal of the solidified continuous phase from the heat exchanger surface.

7. The method of claim 1 or claim 2, wherein the heat exchanger surface is the interior of a tubular conduit.

8. The method of claim 1 or claim 2, wherein the liquid is heated prior to reintroduction to the heat exchange surface.

9. The method of claim 1 or claim 2, wherein the method is conducted at a pressure of 2000 kPa to 3000 kPa.

10. The method of claim 1 or claim 2, wherein the liquid aqueous phase is passed over the heat exchanger at a draw speed of 35-45 Hz.

11. The method of claim 1 or claim 2, wherein the volume of the liquid aqueous phase is 2.9-5.2 liters.

12. The method of claim 1 or claim 2, which is followed by the step of taking the solidified continuous phase and comminuting it to form frozen ice particles, gas hydrates or a mixture thereof.

13. The method of claim 12, wherein the frozen ice particles are added to a frozen confection.

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