FR2789270A1 - Coating of food products by first chilling the products, so coating is solidified onto them, reducing waste caused by solidification of coating on the walls of a mixer - Google Patents

Abstract

Products for coating (X) are chilled (12) to -30 to -60 deg C, and are then mixed (14) with a liquid or paste (S) coating at ambient temperature. Coating material in contact with the products becomes solidified and attached to the products. When a thick layer of coating is required, up to 70% by volume, the mixture of product and coating is chilled again (18). An independent claim is given for equipment to carry out the process.

Description

The present invention relates to a coating process and installation

  of food products with a liquid or pasty coating substance, of the type comprising a step of bringing food products into contact with the coating substance and a step of supplying external refrigerants to cause the freezing of the coating substance

around products.

  Ready meals preserved in the frozen state commonly include a core consisting of a food product such as meat, fish, a vegetable, or even a pastry, completely surrounded by a

  frozen coating (sauce, oil, chocolate ...).

  The coating of food products, from the initially liquid or pasty sauce, is carried out in a mixing apparatus, commonly called "churn", which is equipped with a device for injecting refrigerant, for example liquid nitrogen or liquid carbon dioxide The mixing device has a rotary cylindrical tank with axis

  horizontal. It internally includes pale product mixing.

  The injection of the refrigerant most commonly takes place along the axis

of the tank.

  To ensure the coating of the products, a batch of pre-cooled food products, most often pre-frozen, is introduced into the tank. While the tank is rotated, phases of sauce injection at room temperature and refrigerant injection phases are carried out. Thus, frozen food products being constantly mixed in contact with the sauce are gradually coated with the sauce solidifying under the action not only of the frigories provided by the injected refrigerant but also by transfer from the

product that was pre-frozen.

  Food products coated in such an installation have a certain number of appearance defects resulting from the mechanical stresses applied to the product during the rotation of the tank.

and pale.

  It is further noted that certain sauce particles are frozen away from the products to be coated, and therefore constitute

  undesirable particles commonly called "fines".

  The object of the invention is in particular to provide a method and an installation for coating food products making it possible to provide a solution to the technical problems mentioned above, and in particular: - to obtain coated products having an improved visual appearance;

  - to obtain better control of the coating rate achieved.

  To this end, the invention relates to a process for coating food products with a substance, of the aforementioned type, characterized in that, before bringing the food products and the coating substance into contact, the food products are sub-cooled by supplying external frigories at a temperature below their initial temperature, and in that the food products and said coating substance are subsequently brought into contact without supply of external frigories, the coating around the products being formed by freezing of said coating substance under the action of the transfer of frigories from the products to

said coating substance.

  According to particular modes of implementation, the method can include one or more of the following characteristics:

  - the initial temperature of the products, before the under-

  cooling, corresponds to a frozen state; - The method comprises, after the step of bringing the sub-cooled products into contact with the coating substance, an additional step of freezing the coated food products by adding external refrigerants; - the various stages are carried out continuously; - The food products are sub-cooled to a temperature between - 20 C and -80 C, and advantageously between -30 C and -60 C; and the coating substance is substantially at ambient temperature,

  when it comes into contact with food products.

  The invention further relates to an installation for coating food products with a substance, of the type comprising means for bringing food products into contact with the coating substance and means for supplying external frigories to cause the freezing of said coating substance around the products, characterized in that the means for supplying external frigories comprise a unit for sub-cooling the products to a temperature below their initial temperature, at the outlet of which a unit is provided for bringing sub-cooled food products into contact with the coating substance, the contacting unit being devoid of

  means of supplying external refrigeration.

  According to particular embodiments, the installation may include one or more of the following characteristics: the sub-cooling unit makes it possible to lower the temperature of the products to a temperature below their freezing temperature; - It comprises, at the outlet, means for bringing into contact, means for freezing the coated products, which means for freezing comprise means for supplying external refrigerants; - It includes means for continuously transferring food products between the sub-cooling unit and the unit for bringing sub-cooled food products into contact with the coating substance.

  The invention will be better understood on reading the description which will

  follow, given only by way of example, and made with reference to the accompanying drawings in which: - Figure 1 is a schematic view of a coating installation according to the invention; and - Figure 2 is a schematic view of an alternative embodiment of the installation of Figure 1, comprising an additional step of

deep freezing.

  The coating installation shown in FIG. 1 is a

  continuous coating plant for food products with sauce.

  It allows a coating rate typically between 1 and 60% by volume. It successively comprises a sub-cooling unit 12 and a unit 14 for bringing sub-cooled food products into contact with a coating substance. Transfer means 16 such as a conveyor are here arranged between the outlet of the sub-cooling unit 12 and the unit 14 for bringing food products and the substance into contact (one could of course

  also consider a direct switchover of products from the sub-unit

  cooling 12 in unit 14 without any other form of conveying).

  The sub-cooling unit 12 has an input for

  the introduction of food products such as meatballs.

  These are noted X in the figures. When introduced, these food products arrive at an initial temperature which will depend on each individual case (type of product, type of treatment possibly undergone

  upstream, type of coating to be made ...).

  In the embodiment shown here in FIG. 1, the products arrive frozen, at a temperature of the order of -18 ° C. to -20 ° C., even C. It is understood that for certain applications, the products could arrive at ambient temperature, The sub-cooling unit can

  then also freeze.

  The sub-cooling unit 12 is adapted to lower the temperature of the food products to a temperature below their

  inlet temperature, and in particular between -20 C and -80 C.

  Advantageously, the sub-cooling temperature is

  between -30 C and -50 C or even -60 "C.

  The sub-cooling unit 12 is for example formed by a feed hopper equipped with a device for injecting a cryogenic fluid such as liquid nitrogen or liquid carbon dioxide. As a variant, the sub-cooling unit 12 comprises a cryogenic tunnel or a crusting tunnel, or even a device for immersion in a bath.

cryogenic liquid.

  The contacting unit 14 has an inlet for introducing sub-cooled food products which are conveyed from the contact unit.

  sub-cooling 12 by the transfer means 16.

  The contacting unit 14 further comprises an introduction inlet for the coating substance such as sauce. This is noted S. This coating substance is introduced into the unit 14 at a temperature higher than the temperature of arrival of the products in the unit.

  14, and higher than the proper freezing temperature of the coating.

  Advantageously, the coating substance is introduced at temperature

ambient.

  The contacting unit 14 comprises means for setting in motion sub-cooled food products, such as a screw or a drive belt. The contact is made by projection or fall

  of the coating substance on the products circulating in the unit 14.

  The contacting unit 14 is devoid of introduction means

of external frigories.

  In the contacting unit 14, the coating substance

  initially liquid or pasty applied to under-food products

  cooled constitutes a coating around the products by freezing the coating substance under the effect of the transfer of the frigories of the products

  sub-cooled to the coating substance.

  If the desired coating rate of the products by volume is less than%, the average temperature of the products leaving the unit 14 is generally lower or substantially equal to their freezing temperature. Thus, products can be packaged for their

  marketing directly from unit 14.

  On the other hand, if the desired coating rate is greater than 10%, and in particular between 30 and 60% or even 70% by volume, the average temperature of the coated products leaving the unit 14 is generally

  higher than their freezing temperature.

  Under these conditions, and as shown in FIG. 2, a deep freezer 18 is advantageously arranged downstream of the unit 14. A conveyor 20 is provided for the transfer of the products from the unit 14 to the deep freezer 18 (the same remark already made previously can be reiterated here on the possibility of dropping the products of

  unit 14 in the freezer 18 without any other form of conveying).

  The freezer is advantageously an IQF (Individual Quick Freezing) type freezer, that is to say an individual rapid freezer which ensures a reduction in the temperature of the coating, so that the average temperature of the coated products is less than - 18 C at output

from the freezer.

  The freezer 18 is formed for example of a crusting tunnel, a cryogenic tunnel or means of immersion of the coated products

  in a bath of refrigerant, such as liquid nitrogen.

  In the installation of FIG. 2, for a desired coating rate greater than 10%, the substance coating the products is frozen in contact with the sub-cooled products. However, the quantity of coating substance is too large for the coating to be solidified under the sole action of the transfer of frigories from the products to the coating. Thus, depending on the case, at the outlet of the unit 14, the coating may remain relatively

  pasty, and its temperature is then close to that of the freezing stage.

  The solidification of the coating can then be ensured during the passage of the

products in the freezer 18.

  It is therefore conceivable that with an installation according to the invention, it is possible to obtain real and substantially improved control of the coating rate.

some products.

  Food products do not have to be mixed for a long time, which can be seen to significantly improve the surface finish of the coating layer. In addition, the initial sub-cooling of the food products, before they are brought into contact with the coating substance, in many cases freezes the entire thickness of the coating layer in a single step ( the line being completed by an additional final freezing step for some

  products, in particular with a high coating rate).

  In addition, the contacting unit 14 not being cooled, the coating substance is only frozen on the surface of the sub-cooled products. Thus, no accumulation of frozen coating substance appears on the walls of unit 14. Likewise, no creation

"fines" are not observed.

  But it will also be noted that the invention allows continuous production, and no longer in batch mode as according to the prior state of

the technique.

Claims (10)

  1. Method for coating food products with a coating substance, of the type comprising: - a step of bringing the food products into contact with the coating substance; and a step of supplying external frigories to cause the freezing of the coating substance around the products; characterized in that: before bringing the food products and the coating substance into contact, the food products are sub-cooled by adding external frigories to a temperature below their initial temperature, and in that the food products and said coating substance are subsequently brought into contact without the addition of external frigories, the coating around the products being formed by freezing said coating substance under the action of the transfer of frigories from the products   sub-cooled to said coating substance.   2. Method according to claim 1, characterized in that it comprises, after the step of bringing the sub-cooled products into contact with the coating substance, a step of freezing the food products   coated with the addition of external frigories.   3. Method according to claim 1 or 2, characterized in that the   different stages are carried out continuously.   4. Method according to any one of the preceding claims,   characterized in that the initial temperature of the products, before the   sub-cooling, corresponds to a frozen state.   5. Method according to any one of the preceding claims,   characterized in that the food products are sub-cooled to a temperature between -20 C and -80 C, and advantageously included between -30 C and -60 "C.   6. Method according to any one of the preceding claims,   characterized in that the coating substance is substantially at room temperature when it comes into contact with the products sub-cooled food.   7. Installation for coating food products with a coating substance, of the type comprising: - means (14) for bringing food products into contact with the coating substance; and - means (12) for supplying external frigories to cause the freezing of said coating substance around the products; characterized in that the means for supplying external frigories comprise a unit (12) for sub-cooling the products to a temperature below their initial temperature, at the outlet of which is   provided a unit (14) for contacting under-food products   cooled with the coating substance, the contacting unit (14) being   devoid of means for supplying external cold.   8. Installation according to claim 7, characterized in that the sub-cooling unit makes it possible to lower the temperature of the products to   a temperature below their freezing temperature.   9. Installation according to claim 7 or 8, characterized in that it comprises, at the outlet of the means (14) for bringing into contact, means (18) for freezing the coated products, which means for freezing   include means for supplying external refrigeration.   10. Installation according to one of claims 7 to 9, characterized in   what it includes means (16) for continuously transferring food products between the sub-cooling unit (12) and the unit (14) for bringing the sub-cooled food products into contact with the substance of coating.