FR2770374A1 - Food products are thawed in initially warm and then cold continuously circulated water in an open tank - Google Patents

Abstract

Food products are thawed by immersion in continuously circulated water which is initially maintained at 18 deg C by steam injection and which is then allowed to cool to 6-8 deg C. Food products are thawed by immersing in an open tank (1) containing water maintained for \-1 hr at 18 deg C by steam injection (2) at the tank bottom, interrupting steam injection and allowing the water to cool to 6-8 deg C, the water being continuously stirred by closed circuit circulation by a pump (5). An Independent claim is also included for a food thawing installation comprising an open tank (1) equipped with a bottom steam injection nozzle piping (2) and with a pipeline network (7, 7') connected to a pump (5) and to water feed and return side connections.

Description

 The subject of the present invention is a process for thawing food products, as well as an installation allowing the application of this process.

 The present invention relates generally to equipment and techniques for industrial processing of frozen products, and is more particularly intended to ensure the thawing of blocks of fish commonly used for the preparation of ready meals and in the form of elements agglomerated during their packaging carried out most often on board fishing boats.

 To date, the thawing of products of this type is most often carried out by immersion in basins supplied with running water, which requires, depending on the season a time of the order of 15 to 18 hours, to conduct the term process. For installations with a large volume to be treated, this duration requires the existence of several large pools representing a large size and a high cost.

 There are devices designed to speed up the heating of products.

For example, patent NO FR 2 692 112 (JAEGER
PARTICIPATIONS SA) describes a process for defrosting food products, in particular blocks of meat using a closed airtight tank, mounted around a substantially horizontal axis, driven in rotation and in which a heat exchange is carried out between the products and a fluid brought into or at the periphery of the tank.

Another patent, filed by the company
EGRETIER SA and published under the number FR FR 2 692 443 describes a device for defrosting and cooking various products comprising a rotary cylindrical tank with double jacket with inlet and outlet chutes, water-steam heating means controlled by a distributor sequential and an internal agitator of the blade type, wound in the shape of a propeller defining watertight compartments associated with radial points forming a hedgehog.

 Patent NO FR 2 711 485 (ARMOR INOX SA) relates to a churning, thawing and cooking process for meats which are introduced into a churn in which a vacuum is created before introducing a heat-transfer fluid consisting of steam d 'water.

 The materials which are the subject of these patents, in addition to the fact that they represent very heavy investments, in particular because of the manufacturing constraints linked to their use for food products, are difficult to adapt to the treatment of fish flesh which does not support well. brewing and high temperatures.

 The present invention aims to remedy this state of affairs. It makes it possible in fact to ensure under excellent conditions the thawing of food products such as frozen fish blocks, and this in a very short period of time compared to the usual times.

 The process consists of immersing the products to be defrosted in an open basin containing water containing approximately 2% of salt, maintaining the temperature of this water at 18 OC for at least one hour by injecting steam using ramps placed at the bottom of the basin, then allow the water to cool to 68 OC for 3 hours, stirring being ensured permanently by one or more pumps ensuring circulation of the water in a closed circuit.

In the accompanying drawings, given by way of nonlimiting example of one of the embodiments of the subject of the invention:
Figure 1 shows the defrosting installation seen from above
and FIG. 2 is a vertical section of the basin along the arrows FF of FIG. 1.

 The device, Figures 1 and 2, consists of an open-air basin 1 comprising at its lower part a perforated ramp 2 connected by a pipe 3 to a steam generator 4, a pump 5 causing a circulation of water 6 contained in the basin 1 thanks to pipes 7, 7 'and side outlets 8, 8' for suction and discharge.

 The basin 1 can be made of any material conforming to the hygiene standards relating to food products. It can for example be made of stainless steel, synthetic material or masonry covered with tiles. Its dimensions may be any, provided that its depth is sufficient for the elements to be thawed to be completely covered with water.

 A grid 9, disposed above the ramp 2 for injecting steam, is intended to receive the products to be thawed 10 which are completely immersed in water 6 throughout the duration of the operation.

 This water is added with about 2% of salt in order to promote the separation of the elements constituting the frozen blocks, in particular when these are formed of agglomerated slices of fish.

The addition of salt also gives the water preservative and detergent properties.

 The blocks 10 of frozen fish generally weigh about ten kilos and the slices which constitute it, agglomerated during packaging must be separated and thawed before they can be processed. These blocks are immersed in the water of the basin and deposited on the grid 9. The pump 5 is started in order to cause a forced circulation in a closed circuit to produce a mixing improving the heat and steam exchanges produced by the generator 4 is injected into the bottom of the basin by ramp 2 for a minimum of one hour, so that the water temperature is maintained at 18 OC.

 The steam injection is then stopped and the blocks 10 are left in place until the water temperature has dropped to 6-8 OC, which generally requires 3 to 4 hours.

 The product is then able to be worked and can be removed from the basin 1, the slices separating easily. A new cycle can begin.

 This process provides a clear acceleration of the defrosting time allowing a significant increase in the quantity treated with installations of a determined size, while bringing the product to a temperature in accordance with the legislation on the processing of frozen products. It is indeed possible to treat in 4 to 6 hours the quantities that are currently treated in 15 to 18 hours.

 In addition, existing infrastructure can be used and the installation does not involve heavy investment.

 The positioning of the various constituent elements gives the object of the invention a maximum of useful effects which had not, to date, been obtained by similar devices.

Claims (2)

CLAIMS 1. Process for defrosting food products, intended in particular to ensure the thawing of blocks of frozen fish commonly used for the preparation of ready meals and in the form of agglomerated slices during their packaging carried out most often on board fishing boats , characterized in that the products (10) to be thawed are immersed in an open basin (1) containing water (6), the temperature of which is maintained at 18 ° C. during a first phase lasting at least one hour thanks to the injection of steam by means of ramps (2) arranged at the bottom of the basin then, in a second phase, to stop the injection of steam and to allow the water to cool to 6-8 ° C., stirring being permanently ensured by means of at least one pump (5) ensuring circulation of the water in the basin (1) in a closed circuit.  20. The method of claim 1, characterized in that the water (6) of the basin (1) is added with about 2% of salt in order to facilitate the separation of the elements constituting the frozen products (10).  30. Method according to any one of the preceding claims, characterized in that the water cooling phase (6) has a duration of between three and four hours.  40. Installation for defrosting food products, allowing the application of the process according to the preceding claims,  characterized by the combination of an open basin (1) comprising at its lower part a perforated ramp (2) supplied by a steam source (4) and a network of pipes (7, 7 ') connected to at least one pump (5) and to side suction and discharge outlets (8, 8 ') arranged to cause a circulation in closed circuit of the water (6) contained in said basin in order to ensure permanent stirring during thawing .  50. Installation according to claim 4, characterized in that a grid (9), intended to receive the products (10) to be defrosted is arranged at the bottom of the basin (1) above the ramp (2) d steam injection.