MXPA00007101A - Frozen food product - Google Patents

Abstract

A frozen food product comprising AFPs, said product having an average ice crystal size of 0.01 to 20 micrometer, wherein said crystal size is maintained between 0.01 and 20 micrometer upon storage for 3 weeks at -10°C. Additionally a process for the manufacture of the frozen food product comprising AFPs is described, wherein the process comprises one or more of the following steps:(i) a (pre-)freezing step which is a nucleation dominated freezing step;(ii) a (post-)compaction step using a screw extruder or a compactor.

Description

FROZEN FOOD PRODUCT TECHNICAL FIELD OF THE INVENTION The invention relates to food products containing antifreeze peptides (AFPs), in particular to frozen food products containing AFPs.

BACKGROUND OF THE INVENTION Antifreeze peptides (AFPs) have been suggested to improve the freezing tolerance of food products. In particular, it has been suggested that some AFPs may be able to increase the smooth texture of frozen food products such as ice cream. Until now, however, the use of AFPs has not been applied to commercially available food products. One reason for this is that until now it has been proven that it is difficult to reproducibly produce a frozen food product having the desired texture and desired feeding characteristics.

WO 90/13571 describes antifreeze peptides produced chemically or by recombinant DNA techniques from plants. AFPs can be suitably used in food products such as ice cream. There are no guidelines on how to obtain soft textures. WO 92/22581 describes AFPs from plants, which can be used to control the growth of ice crystals. This document also describes a process for extracting a polypeptide composition from the intercellular spaces of the plants, by infiltration of leaves with an extraction medium without breaking the plant cells. Applicants believe that one of the possible reasons for the lack of texture desired in frozen food products containing AFP is that although AFP is able to inhibit recrystallization, it is often not able to avoid the less favorable hard and brittle textures. Applicants believe that one of the explanations for this is that AFPs seem able to control the growth of ice crystals. However, the presence of AFP can also lead to an adverse effect, since ice crystals tend to form aggregates that lead to hard and brittle products. In this way, the texture of the product is adversely affected during the manufacturing process. The present invention is therefore directed to defining manufacturing conditions that improve the texture of frozen food products containing AFP. Surprisingly, it has now been found that if the conditions for producing the frozen food material are carefully chosen, this leads to an improved texture. In particular applicants have found that if the production process includes the use of one or more of the following steps: i) a (pre) freezing step which is a nucleation-dominated freezing process. ii) a (post t-) compaction step using a screw extruder or a compactor (piston); this leads to the aggregation of the ice crystals which is minimized and therefore results in more favorable textures of the frozen product, said texture being maintained for prolonged storage periods. In general, in the freezing of a composition, two different phases can be observed: at the beginning of the freezing process, many small ice crystals are rapidly formed. This phase is called the nucleation phase of the freezing process. After the nucleation process the remaining part of the composition freezes on the nucleated surface and thereby contributes to the development of the ice crystals. This phase in the freezing process is called the growth or development phase. In a growth-dominated freezing process, most of the composition is frozen during the growth phase, in a nucleation-dominated freezing process, most of the composition is frozen during the nucleation phase. The traditional freezing processes for frozen confectionery products, for example, involve the use of scraped surface heat exchangers, whereby the mixture to be frozen is subject to cutting during the freezing process. In general, this freezing process takes 5 to 30 minutes for the product to reach a temperature of -5 ° C or lower. In this process initially some nucleation of the ice crystals occurs, followed by a period where the growth of the ice crystals dominates. Alternative freezing processes, which for example are used for the freezing of water ice, involve the freezing of low cut or at rest of the mixture, for example, by filling a mold and immersing the mold inside a bath cold, for example, filled with brine. In this process the initial nucleation of ice crystals takes place on the surface of the mold, the internal part of the product then tends to freeze more slowly in a process of freezing dominated by growth. Applicants have now surprisingly found that aggregation in products containing AFP can be significantly reduced if a nucleation-dominated freezing process is chosen. Such a freezing process is generally characterized by a short freezing time in combination with the formation of small ice crystals. Preferably, the freezing process is carried out under low cut or at rest freezing conditions.

DESCRIPTION OF THE INVENTION Accordingly, in a first aspect the present invention relates to a process for the manufacture of a frozen food product comprising AFPs, wherein the process comprises one or more of the following steps; (i) a step of (pre) freezing which is a freezing process dominated by nucleation; (ii) a (post-) compaction step using a screw extruder or a compactor (piston). For purposes of this invention, the term "AFP" has the meaning well known in the art, see for example "Antifreeze proteins and their potential use in frozen food products", Marilyn Griffith and K. Vanya Ewart, Biotechnology Advances, Vol. 13, pp. . 375-402, 1995. The present invention is directed to provide the food manufacturer with greater flexibility for the use of an AFP material in frozen food products when directed to obtain a product with improved recrystallization properties in combination with a good texture. In particular, it has been found that the texture of frozen food products containing AFPs can be remarkably improved by carefully controlling their production method. The invention is based on the finding that if the frozen product is produced by a process that involves one or more of the following steps of the process: (i) a step of (pre) freezing which is a freezing process dominated by nucleation; (ii) a step of (post-) compaction using a screw extruder or a compactor (piston); this can lead to an improved texture of the product. Applicants believe that it is well within the ability of the skilled person to select those freezing methods that result in nucleation-dominated freezing processes. Preferably, when the freezing process is a nucleation-dominated freezing process, the freezing process is such that the product reaches a temperature of -5 ° C or less within 30 seconds, preferably 0.01 to 25 seconds, more preferably in 1 to 15 seconds. Also preferably, when the freezing process is a nucleation-dominated freezing process, the freezing process is such that it results in many relatively small crystals, whereby the average crystal size is 0.01 to 20 microns, more preferably from 0.01 to 15 micrometers, and most preferably from 0.01 to 10 micrometers. For example, rapid freezing processes tend to be dominated by nucleation. Suitable processes may for example involve: (a) surface freezing, preferably freezing by film on a cold surface; (b) freezing of supercooled systems; (c) decompression freezing; (d) freezing by very low temperatures; (e) rapid particulate freezing, preferably condensation freezing. Other rapid freezing processes will be apparent to those skilled in the art, and are also encompassed within the scope of the present invention. Preferably the freezing processes involve the absence of cutting or low cutting. Surface freezing preferably involves the application of a thin film or discrete particles on a cold surface, optionally followed by removal of the frozen material. Preferably, the film or particle thickness is 0.01 to 5 mm. The cold surface is preferably at a temperature below -15 ° C, more preferably below -20 ° C, most preferably below -25 ° C. Suitably, the surface can be cooled by the application of liquid nitrogen, glycols or methanol. The removal can be carried out by any suitable means, for example by scraping, thereby producing frozen particles, for example flakes or pellets which can then be further processed. Obviously, during further processing care must be taken to avoid substantial melting of the composition, which may result in re-freezing dominated by growth. In a highly preferred embodiment, surface freezing involves film freezing on a drum freezer which is for example cooled with liquid nitrogen or methanol, followed by removal of the film from the drum freezer. In a further embodiment of surface freezing, a cryogenic plate freezer cooled with liquid nitrogen is used to produce the frozen pellets. An alternative form of surface freezing involves the preparation of a cold core, followed by the application of the mixture to be frozen, to the core, for example by immersion or spraying, whereby a relatively thin film adheres to the cold core. Advantageously, such a cold core can for example be a very cold ice core (for example, immersed in liquid nitrogen) where a thin film of water ice comprising AFP is frozen above. Yet another method to achieve fast nucleation-dominated freezing is to produce a supercooled system at low temperatures, followed by sudden freezing, for example, by applying a shock to the supercooled liquid. The rapid freezing of a supercooled liquid in general is a freezing process dominated by nucleation. Preferably, the supercooled liquid has a temperature of at least 1 degree below the melting point, more preferably 1-20 degrees below the melting point, for example 2-10 degrees below the melting point. A third method to achieve rapid freezing dominated by nucleation is to use decompression freezing. This involves the application of high pressures to a liquid system, while the cooling of this is followed by the elimination of the overpressure. This elimination of the pressure then results in a rapid freezing dominated by nucleation. Preferably, the pressure to be applied is from 100 to 3000 bar, for example from 200 to 2000, in general from 300 to 1300 bar. The temperature of the product before removal of the overpressure is preferably at least 5 degrees below the melting point at atmospheric pressure, preferably 6-10 degrees below the melting point. A fourth method to ensure freezing dominated by nucleation is the application of very low temperatures. For example, small droplets of material to be frozen can be immersed in a fluid freezing medium, for example liquid hexane or liquid nitrogen. Preferably, the freezing temperature for this method is less than -50 ° C. This method works best for relatively thin or small projects that are going to be frozen. The small products are preferably less than 5 grams, more preferably from 0.001 to 3 grams, most preferably from 0.01 to 1 gram and may be for example drops of liquid immersed in the freezing medium. Relatively thin products may for example be sheets or thin streams of products, preferably having at least one dimension of less than 2 cm, more preferably 0.1 to 0.5 cm. The product for use in this method can for example be directly immersed in the freezing liquid; alternatively, however, the products are first contacted with a protective layer, for example filled on a mold, pumped through a tube, whereby they are brought into contact with the cooling medium. A fifth preferred method for freezing food products of the invention involves rapid freezing of the particles, preferably condensation freezing. This can be achieved, for example, by spraying a liquid mixture that is to be frozen in a very cold gaseous environment or in a cooled environment. An especially preferred method for rapid freezing of a particulate liquid is condensation freezing. More preferred is the use of techniques that are for example the use of artificial snow production. The production of artificial snow is widely described in the literature. Artificial snow is often produced in so-called snow cannons, whereby the water is frozen by spraying a mixture of water and pressurized air. Preferably, the snowmaking takes place in an environment having a temperature of less than -3 ° C, more preferably -5 to -50 ° C and a relative humidity of less than 75%, more preferably less than 50%. The frozen particles obtained by this fifth method may vary in size, but in general the average diameter of the particles will be up to 10 mm, more preferably less than 5 mm. In general, each of the particulates will comprise aggregated, multiple ice crystals. The freezing of confectionery products frozen by means of a screw extruder is described, for example, in: EP-713,650 (Societe des Produits Nestle), EP-410,512 (HMF Krampe & Co. Et al); EP-561,118 (Milchhof-Eiskrem GmbH et al.), EP-351,476 (Goavec S.A. Societe Dite). Preferably, the manufacturing process of the invention involves the use of a screw extruder by which the extrusion temperature of the frozen product is -8 ° C or less, more preferably -10 to -25 ° C, more preferably from -12 to -20 ° C. Screw extruders suitable for use in the process of the invention may for example be twin screw extruders such as described for example in European Patent EP-561,118. Single screw extruders can also be used. Extruders that combine more than one function of the ice cream manufacturing process can also be used (see for example EP-713, 650). The conditions under which the screw extruder operates may vary, for example, depending on the type and size of the extruder used. The applicants believe that it is very within the ability of the skilled person to select those operating conditions such that a favorable quality of the product is obtained. Examples of suitable operating conditions are given in the examples. Alternatively, a compactor can be advantageously used in the manufacture of frozen food products with AFPs. All suitable compactors such as presses can be used, especially preferred is the use of the piston compactors, by means of which pressure is applied to the food products by means of the movement of a piston. Traditionally, piston compactors have for example been used in stuffing sausages or sausages. Again, the applicants believe that it is within the ability of the skilled person to select the appropriate operating conditions of the compactor (piston). Preferably, the invention relates to a process for the manufacture of a frozen food product comprising AFPs, wherein the process comprises the following steps: (i) a step of (pre) freezing which is a freezing process dominated by nucleation; and (ü) a step of (post-) compaction using a screw extruder or a compactor (piston). The use of a screw extruder or compactor can be applied very advantageously to products that have been pre-frozen under conditions such that a frozen (partial) particulate material is produced eg flakes, pellets, powders, extended rods or sheets. For these pre-frozen products, the use of screw extruders or compactors (pistons) can advantageously lead to the compaction of the particulate material into a more solid structure. The entire manufacturing process of the frozen products of the invention may comprise additional optional steps, in addition to pre-freezing and / or screw extrusion or piston compaction. For example, the mixing of ingredients, maturation, pasteurization, homogenization, pre-aeration, etc. These optional steps can take place in any appropriate order. As described above, one of the characteristics of the nucleation-dominated freezing process is the formation of many small ice crystals. Applicants have found that the combined use of AFPs as an ingredient and the nucleation-dominated freezing process leads to a particular advantageous texture of the products to be frozen, said textures being maintained for prolonged periods of storage. Particularly, the freezing process dominated by nucleation can very advantageously be used for the production of a frozen, particulate material. Examples of these are frozen flakes, frozen droplets (small), frozen powders, pellets, frozen rods and frozen snow. Surprisingly, the particulate materials formed by the process of the invention have a reduced tendency to aggregation and therefore the free-flowing nature of the particulate material can be maintained on the storage, even if the storage temperature is relatively high. In addition, applicants have found that the use of a screw extruder or compactor (piston) in the production of frozen food products containing AFP is very advantageous, since this can also lead to very small ice crystal sizes, which They can be maintained for extended periods of storage. Preferably the freezing conditions are chosen such that the average size of the ice crystals in the final frozen product is 0.01 to 20 microns, the sizes of the ice crystals are to be maintained in said interval after storage at -10 °. C for 3 weeks. Preferably, the average size of the ice crystals remains less than 15 microns, for example less than 12 or even 10 microns during storage for 3 weeks at -10 ° C. If the freezing process involves a freezing process dominated by nucleation in the absence of any compaction process, the frozen product provided may be a particulate food product. On the other hand, if a screw extruder or a compactor is used (piston), products can be formed that are homogeneously solid and have no particulates (thin). Preferably, the non-particulate products of the invention have a smaller dimension of more than 2 cm, more preferably greater than 2.5 cm, most preferably greater than 3 cm. After freezing, the product can be further handled. For example, the product can be filled inside packages or packages, say 0.05 to 10 liters and then stored. Alternatively, the product can be further shaped into the final product. For example, the product can be used to be shaped into ice cream cupcakes. A further advantage of the invention is that when the process used includes postcompaction using either a screw extruder or a compactor (piston), the products of the invention in general do not need to be subjected to a hardening step, for example in a hardening tunnel. This advantage has for example been suggested for products with AFP in general in U.S. Patent No. 5,620,732 (Pillsbury). The process as described in U.S. Patent No. 5,620,732 however has as a disadvantage that it is not suitable for the production of luxury bar products. These products are traditionally made by extruding and cutting a block of ice cream, hardening the block, followed by the insertion of the bar and coating it, for example, with chocolate or fruit snow. If the hardening step is omitted for products containing AFP, this leads to problems in the subsequent handling for example during the insertion of the bar or the additional coating. Surprisingly, applicants have found that the combined use of AFPs and post-compaction either with a screw extruder or compactor (piston) now makes it possible to produce luxurious bar products without the use of a hardening step. The frozen food products of the invention can be any food product that can be stored and / or eaten in the frozen state. Examples of frozen food products that may contain AFPs are processed food products such as for example frozen confectionery products, for example dough, pasta, cakes, etc., frozen culinary products eg soups, sauces, pizzas, frozen vegetable products such as a compote or syrup, mashed potatoes, tomato paste, etc. Applicants have found that the method of the invention is best applicable to food systems that are fluid or liquid prior to freezing. A highly preferred food product according to the invention is a frozen confectionery product. For purposes of the invention, the term frozen confectionery product includes frozen confections containing milk, such as ice cream, frozen yogurt, sorbet, malted and custard or frozen custard; as well as frozen confections that typically do not contain milk such as snow, sorbets, granitas and frozen fruit purées. The especially preferred products of the invention are ice cream and snow. The frozen products according to the invention can be aerated. For example, the level of aeration is greater than 50%, more preferably greater than 70%, more preferably greater than 90%. In general, the level of aeration will be less than 400%, more generally less than 300%, and more preferably less than 200%. Aeration may for example take place before or during freezing. If the product is pre-frozen by one or more of the above-described nucleation dominated freezing processes, then preferably the aeration takes place before the pre-freeze. Preferably, the level of AFPs in the frozen food product of the invention is from 0.0001 to 0.5% by weight, based on the final product. The AFP for use in products of the invention can be any AFP suitable for use in food products. Examples of suitable sources of AFP are for example given in the aforementioned article by Griffith and Vanya Ewart and in patent applications WO 98/04699, WO 98/04146, WO 98/04147, WO 98/04148 and WO 98/22591. The AFPs can be obtained from their sources by any suitable process, for example the isolation processes as described in the aforementioned documents.

A possible source of materials with AFP is fish. Examples of fish AFP materials are AFGP (eg obtainable from Atlantic cod, Greenland cod and small cod), Type I AFP (eg obtainable from winter flounder, yellowtail flounder, short-horned scorpion and speckled scorpion), Type II AFP (eg obtainable from sea crow, spherical and Atlantic herring) and Type III AFP (eg obtainable from ocean haddock, Atlantic sea wolf, radiated blended, blended from rocks and zoarcido de Laval). A preferred example of the latter type is described in WO 97/02343. Another possible source of AFP material is invertebrates. Bacterial AFPs can also be obtained. A third possible source of AFP material is plants. Examples of plants containing AFPs are garlic-mustard, aster or blue daisy, spring oats, winter cress, winter cauliflower, Brussels sprouts, carrots, dicentras, lechetrenza, yellow lily, winter barley, water leaf Virginia, narrow-leaf banana, banana, spikelet, Kentucky bluegrass, Eastern poplar or shock, white oak, winter rye, sweet-sour solana, potato, chickweed, ilex tooth, spring and winter wheat, triticali, periwinkle , violet and grass. You can use species of natural origin or species that have been obtained through genetic modification. For example, microorganisms or plants can be genetically modified to express AFPs and AFPs can then be used according to the present invention. Genetic manipulation techniques can be used to produce AFPs. Genetic manipulation techniques can be used to produce AFPs having at least 80%, more preferably more than 95%, most preferably 100% homology to AFPs directly obtained from natural sources. For purposes of the invention, these AFPs that possess this high level of homology are also encompassed within the term "AFPs". The techniques of genetic manipulation can be used as follows: An appropriate cell or host organism could be transformed by a gene construct containing the desired polypeptide. The nucleotide sequence encoding the polypeptide can be inserted into an appropriate expression vector that encodes the elements necessary for transcription and translation, and in such a way that they will be expressed under appropriate conditions (e.g. in the proper orientation). and in the structure of correct reading, and with the sequences of direction to the objective and of expression, appropriate). The methods required to construct these expression vectors are well known to those skilled in the art. A number of expression systems can be used to express the sequence encoding the polypeptide. These include, but are not limited to, bacterial, insect cell, yeast systems, plant and plant cell culture systems, all transformed with appropriate expression vectors. A wide variety of plants and plant cell systems can be transformed with the nucleic acid constructs of the desired polypeptides. Preferred embodiments could include, but are not limited to, corn, tomato, tobacco, carrots, strawberries, rapeseed and sugar beet.

For purposes of the present invention, preferred AFPs are fish or plant derivatives. Specifically preferred is the use of type III fish proteins, more preferably HPLC 12 as described in our case WO 97/02343. From plants, the use of carrot or grass AFPs is especially preferred. For some natural sources, AFPs may consist of a mixture of two or more AFPs. Preferably, those AFPs that have significant properties of inhibition of ice recrystallization are chosen. This can be measured according to Example I. AFPs preferably according to the invention provide an ice particle size after recrystallization, as measured according to the examples, less than 20 μm, more preferably from 5 to 15 μm. Preferably, the level of solids in the frozen food product (eg, sugar, fat, flavoring, etc.) is greater than 2% by weight, more preferably from 4 to 70% by weight. The method of preparation of the frozen food product of the invention can be selected from any suitable method for the preparation of frozen food products. AFPs can generally be added in different stages of preparation, for example this can be added in the first premix of the ingredients or can be added later during a later step of the preparation process. For some applications it is sometimes preferred to add the AFPs at a relatively late stage in the production process, for example after the (partial) pre-freezing of the product. The freezing process of the invention will generally include freezing the composition by saying at a temperature of less than -2 ° C, say from -80 to -5 ° C. If desired, the products of the invention need not be subjected to low temperatures to prevent the growth of ice crystals. Therefore, the products can be frozen for example without the need to use low temperatures, say under -25 ° C and can also be stored at temperatures that are higher than the traditional temperatures for storing frozen confectionery products. Preferably, the freezing process involves conditions of low cut or lack of cut, for example, found in the freezing of filled molds, immersion, thin film crystallization, introduction in liquid nitrogen, etc. For some applications it may be advantageous to include a mixture of two or more different AFPs in the food product. One reason for this may be, for example, that the plant source for the AFPs to be used contains more than one AFP and it is more convenient to add these, for example because both are present in the AFP source to be used. Alternatively, it may sometimes be desirable to add more than one AFP from different sources. The invention will now be illustrated by means of the following examples.

Example I Method for the determination of whether an AFP has ice recrystallization inhibition properties.

The properties of inhibition of recrystallization can be measured using a modified "splash test" (Knight et al, 1988). 2.5 μl of the solution under investigation in 30% sucrose (w / w) is transferred to a 16 mm circular coverslip, appropriately marked, clean. A second coverslip is cut over the top of the drop of solution and the sandwich is pressed together between the index and the thumb. The sandwich is immersed in a hexane bath maintained at -80 ° C in a dry ice box. When all the sandwiches have been prepared, the sandwiches are transferred from the hexane bath at -80 ° C to the observation chamber containing hexane maintained at -6 ° C using forceps previously cooled on dry ice. After the transfer at -6 ° C, it can be seen that the sandwiches change from a transparent to an opaque appearance. The images are recorded by video camera and recorded in an image analysis system (LUCIA, Nikon) using a 20x objective. The images of each sample are recorded at time = 0 and again after 60 minutes. The size of the ice crystals in both trials is compared by the placement of slides inside a temperature-controlled cryostat cabinet (Bright Instrument Co., Ltd, Huntington, United Kingdom). The images of the samples are transferred to a Quanti et 520 MC image analysis system (Leica, Cambridge, United Kingdom) by means of a monochromatic Sony CCD camcorder. The determination of the size of the ice crystals was done by pull or manual extraction around the ice crystal. At least 400 crystals were measured for each sample. The size of the ice crystal was taken as the longest dimension of the two-dimensional projection of each crystal. The average crystal size was determined as the average number of individual crystal sizes. If the size at 30-60 minutes is similar or only moderately (less than 10%) increased compared to the size at t = 0, and / or the size of the crystal is less than 20 microns, preferably from 5 to 15 microns, this it is an indication of the good recrystallization properties of ice crystals.

Example II The following formulation: 15% by weight of sugar 10% by weight of skimmed milk powder 10% by weight of butter fat 0.2% by weight of locust bean gum 0.2% by weight of monoglyceride 0.01% by weight of AFP * the rest of water * HPLC AFP 12 as described in WO 97/02343 It was produced using conventional ice cream processing equipment. The premix was cooled to 0 ° C before passing through a Megatron Model MT1-63 / 3A mixer, operating at 8000 rpm. The mixer had a free space of 0.5 mm between the rotor and the stator. An equal volume of air was injected into the premix immediately before the mixing device. This gave a 90% overflow in the premix. This aerated premix was frozen by applying a thickness of 0.5 mm on a Gerstenberg and Agger pilot cooling drum, which has a surface area of 0.2 m2, and operating at a rotational speed of 5 rpm. The drum was cooled with liquid nitrogen. The frozen flakes were removed using a plastic scraper blade after one revolution (for example after 12 seconds). The flakes had a temperature of -20 ° C. The leaflets were harvested, hardened in a forced air freezer at -35 ° C, then stored at -25 ° C. The ice cream flakes were soft and creamy. The particle size of the ice crystals was determined as in Example I. The size of the ice crystal was very well below 20 microns and remained below 20 microns after storage for 3 weeks at -10 ° C.

Example III An ice cream premix of the formulation of Example II was produced using conventional ice cream processing equipment. The premix was cooled to 0 ° C before passing it through a Megatron model MT1-63 / 3A mixer, operating at 8000 rpm and with a free space of 0.5 mm between the rotor and the stator. An equal volume of air was injected into the premix immediately before the mixing device. This gave a 90% overflow in the premix. The aerated premix was pumped through a plate heat exchanger, whose cooling temperature was controlled at -7 ° C, a temperature warmer than the metastable limit of -8 ° C for the premix. The premix came out of the heat exchanger at -6 ° C; the melting temperature of the premix was -2 ° C. No ice was present in the premix, for example it was subcooled. The premix was emptied in conventional metal molds for ice plates, which were cooled by brine at -35 ° C. Sticks were inserted into the molds. After 15 minutes, the frozen ice cream products were removed from the molds. The products were stored at -25 ° C. The ice cream products had a smooth and creamy texture.

Comparative Example IV An ice cream premix of the formulation of Example II was produced using conventional ice cream processing equipment. The premix was cooled to 0 ° C before passing through a Megatron model MT1-63 / 3A mixer, operating at 8000 rpm and with a 0.5 mm gap between the rotor and the stator. An equal volume of air was injected into the premix immediately before the mixing device. This gave a 90% overflow in the premix. The aerated premix was frozen in a scraped surface heat exchanger for ice cream, standard (Crepaco W104, supplied by APV, operating with an 80 series mixer at a rotational speed of 140 rpm) at a speed of 200 liters / hour . The exit temperature was -5 ° C after a residence time of 90 seconds. The ice cream was then hardened in a forced air freezer at -35 ° C, before storage at -25 ° C. The ice cream was found to be hard and brittle.

Example V A liquid premix was prepared for the preparation of ice cream, when mixing: Ingredient by weight Nonfat dry milk 10.00 Sucrose 13.00 Maltodextrin (MD40) 4.00 Locust bean gum 0.14 Butter oil 8.00 Monoglyceride (palmitate) 0.30 Vanillin 0.01 AFP ** 0.01 Water the rest ** AFP is carrot AFP prepared as follows (WO 98 / 2259). Carrots (Daucus carota cv Autumn King) were grown in individual pots. When the plants were appropriately 12 weeks old, they were transferred to a cold room and kept at 4 ° C in constant light for 4 weeks for cold acclimation. The plants were watered three times a week. The root extract from the carrot roots acclimated to the cold, was prepared by rubbing the carrots cold acclimated, freshly harvested (as described above) in cold water. The upper parts were removed and the juice was extracted using a domestic juice extractor (Russell Hobbs, Model No. 9915). The juice was frozen in 1 liter blocks and stored at -20 ° C before harvest for use in ice cream formulations.

The composition was pre-frozen at -5 ° C and aerated to a 100% overflow in a traditional scraped surface heat exchanger. The composition was further frozen in a single screw extruder having a barrel length of 0.75, a diameter of 0.2 meters, a screw spacing of 0.135 meters (2 starts) and a screw channel depth of 15 m. The yield was 280 kg / hour, the inlet pressure was 7 barg and a constant torque of the screw was 1500 Nm. The outlet pressure was 8 barg. The screw extruder was cooled such that the extrusion temperature was -12 ° C. As a comparison (B) the same product was produced using a conventional scraped surface heat exchanger. A comparison (C) of the same product was produced by the screw extruder process, described above, whereby the AFP was omitted from the formulation. The resulting products were stored for 3 weeks at -10 ° C.

Composition A had a smoother and creamier texture than formulations B and C.

Example VI A liquid premix was prepared for the preparation of ice cream by mixing: Ingredient% by weight Skimmed milk powder 10.00 Sucrose 13.00 Maltodextrin (MD40) 4.00 Locust bean gum 0.14 Butter oil 8.00 Monoglyceride (palmitate) 0.30 Vanillin 0.01 AFP (from Example V) 0.01 Water the rest The liquid mixture was continuously aerated at a throughput of 60 liters / hour using a high speed rotor / stator mixer (Megatron, Kinematica AG) to an overflow of 100% The temperature of the mixture was 5 ° C and a mixer speed of 1600 rpm was used. A pressure of 3 barg was maintained with the mixing head. The aerated mixture was then continuously spread as a 0.1 mm film on the surface of a drum freezer cooled with a methanol solution at -28 ° C. The drum freezer was rotated at a speed of 1 rpm. After a complete revolution the frozen film at -10 ° C was continuously removed by means of a scraper blade to form frozen flakes. Frozen leaflets were compressed in batches using a piston compression device. The compressed ice cream was extruded through a boguilla and packed for storage. The size distribution of the ice crystals of the frozen material was measured as follows: by placing coating plates smeared with the compositions to be tested inside a temperature controlled cryostat cabinet (Bright Instrument Co. Ltd., Huntington, United Kingdom). Images of the samples are transferred to a Quantimet 520 MC image analyzer system (Leica, Cambridge, UK) by means of a Sony monochromatic CCD camcorder. The determination of the size of the ice crystals was carried out by manual pulling around the ice crystals. At least 400 crystals were measured for each sample. The size of the ice crystals was taken as the longest dimension of the two-dimensional projection of each crystal. The average size of the crystals was determined as the average number of individual crystal sizes. The average size of the ice crystals was 5.8 micrometers for the fresh sample with AFP, and 7.2 micrometers for the fresh sample with AFP. After storage for 3 weeks at -10 ° C the particle size of the sample with AFP was 7.7 microns, without AFP of 43.2 microns.

Example VII Example VI was repeated, but now the pre-frozen flakes are fed via a hopper to a screw extruder (CP1050, APV) which was cooled with a methanol solution at -28 ° C. Fully co-rotating geared screw rotors were adjusted and the rotational speed of 10 rpm was used. The ice cream was compressed and extruded at a temperature of -12 ° C.

Example VIII A liquid premix was prepared for the preparation of ice cream by mixing: Ingredient% by weight Skimmed milk powder 10.00 Sucrose 13.00 Maltodextrin (MD40) 4.00 Locust bean gum 0.14 Butter oil 12.00 Monoglyceride (palmitate) 0.30 Vanillin 0.01 AFP * 0.01 Water the rest * AFP is HPLC-12 AFP as described in WO 97/02343.

The mixture was aerated at 100% overflow as in Example VI. The aerated mixture was frozen in the form of pellets with a diameter of 10 mm using a cryogenic freezing unit (British Oxygen Company). The freezing surface consisted of a horizontal rotating table, which was obtained using liquid nitrogen at a temperature of -100 ° C. The air above the rotating freezing table was also cooled to a temperature of -120 ° C. The turntable was rotated at 5 rpm. After a simple rotation, the frozen pellets were swept from the freezing surface and harvested. The frozen pellets were then fed to a screw extruder under the same conditions as in Example VII.

Claims (17)

1. A process for the manufacture of a frozen food product comprising antifreeze peptides, wherein the process comprises: (i) an optional fast freezing step such that the product reaches a temperature of -5 ° C or less within 30 seconds; and (ii) a compaction step using a screw extruder or a compactor.

2. A process according to claim 1, wherein in step (i) the product is frozen at a temperature of -5 ° C or less than 0.01 to 25 seconds.

3. A process according to claim 1, wherein in step (i) the product is frozen at a temperature of -5 ° C or less than 1 to 15 seconds.

4. A process according to any of the preceding claims, wherein step (i) involves one more of: (a) surface freezing, preferably film freezing, on a cold surface; (b) the freezing of a supercooled system; (c) decompression freezing; (d) freezing at very low temperatures; (e) rapid freezing of the particulate, preferably freezing by condensation.

5. A process according to any of the preceding claims, wherein step (i) involves freezing the product by drum.

6. A process according to claim 1, wherein in step (ii) a screw extruder is used.

7. A process according to claim 1, wherein in step (ii) the extrusion temperature of the frozen food product is less than -8 ° C.

8. A free-flowing, particulate food product comprising antifreeze peptide, which maintains its free-flowing nature during storage, obtainable by rapid freezing of the food product, such that the food product reaches a temperature of -5 ° C or less within 30 seconds.

9. A free-flowing particulate food product according to claim 8, wherein the food product is rapidly frozen such that the food product reaches a temperature of -5 ° C or less in 0.01 to 25 seconds.

10. A free-flowing particulate food product according to claim 8, wherein the food product is rapidly frozen such that the food product reaches a temperature of -5 ° C or less in 1 to 15 seconds.

11. A free-flowing particulate food product according to claim 8, wherein the food product is rapidly frozen using one or more of: (a) surface freezing, preferably film freezing, on a cold surface; (b) the freezing of a supercooled system; (c) decompression freezing; (d) freezing at very low temperatures; (e) rapid freezing of the particulate, preferably freezing by condensation.

12. A free-flowing particulate food product according to claim 8, wherein the food product is rapidly frozen by drum freezing.

13. A free-flowing particulate food product according to claim 8, wherein the food product is a frozen confectionery product.

14. A free-flowing particulate food product according to claim 8, wherein the antifreeze peptide is AFP Type III HPLC 12.

15. A process for providing a particulate, free-flowing food product, comprising rapid freezing of the food product such that the food product reaches a temperature of -5 ° C or less within 30 seconds.

16. A process for providing a particulate, free-flowing food product, wherein the food product is rapidly frozen by drum freezing.

17. The use of a process comprising rapid freezing of a food product, such that the food product reaches a temperature of -5 ° C or less within 30 seconds, to provide a particulate, free-flowing food product.