Apparatus and method for treating food products

Description

BACKGROUND OF THE INVENTION

The present invention relates to an apparatus comprising a heat exchanger with cylindrical geometry, having a stator and a rotor within the stator, defining a passage between the stator and the rotor and comprising cooling means that are operatively active on the outer surface of the stator; and pumping means, to push the food products through said passage.

The present invention also relates to a method for cooling and aerating substantially fluid or viscous food products, which provides for the use of a heat exchanger with cylindrical geometry, having a stator and a rotor within the stator and defining a passage between the stator and the rotor.

Within the food industry and, in particular, in the sweets sector, there is the need to treat food products, constituted by substantially liquid or viscous mixtures, e.g. mixes for snacks or stuffed pastries, creams, juices or jams. In particular, within the field of snack production, the food products constituted by creams or other fillings for the snacks are subjected to a hydration process, to increase their mass and improve product preservation. Said hydration is followed by a pasteurisation process, which entails a rise in the temperature of said food products. Subsequently, the same food products are subjected to an aeration process, to increase their volume and make them softer. Said aeration process essentially consists of the emulsion of a certain quantity of air or other fluid within the food products. For said emulsion to take place correctly and effectively, two conditions must be met: the products must be at a relatively low temperature (no higher than about 20° C., but the optimal temperature depends on the product) and they must be characterised by a substantially turbulent motion. If the aforesaid conditions are not met, the emulsion takes place incorrectly, with consequent damage to the final product, both from the point of view of taste and from the point of view of appearance. Therefore, there is a need to rapidly lower the temperature of the treated food, at the end of the pasteurisation process, in order to perform the aeration process correctly.

In this light, technical solutions are known which allow to cool the food products at the end of the pasteurisation process. Moreover, technical solutions are known which allow to aerate said food products, after their cooling. With regard to cooling, the use is known of heat exchangers with scraping surface, as described for example in the patent documents U.S. Pat. No. 6,056,46 or EP0503274. Said exchanger comprise a stator and a rotor with cylindrical geometry. The rotor rotates inside the stator and between the outer surface of the rotor and the inner surface of the stator there is a passage, into which the food products are thrust. The surface of the stator, lapped externally by a cooling fluid, exchanges heat with the food product that flows within it, cooling it. Moreover, said exchangers comprise scraping elements, able to prevent the food products from adhering to the inner surface of the stator, because of the temperature gradient. With regard to the aeration process, the separate use is known of emulsifiers, comprising a stator and a rotor with cylindrical geometry. In this case, too, the product to be treated is pushed into a passage between the rotor and the stator, together with a flow of air (or of another fluid). The rotor and the stator define, on the surfaces that face each other, a plurality of teeth which, in the rotating motion, mutually intersect, without scraping the surfaces that delimit the passage. In this way, the products to be treated are imparted a turbulent motion (within said passage), which favours the emulsion of air with the products.

The known solutions described above have numerous drawbacks. First of all, the presence of two distinct apparatuses, one to cool the pasteurised products and one to emulsify a fluid with the products themselves, limits compactness and increases the bulk of the apparatus, as a whole. Moreover, known emulsifiers are inconvenient to clean, since they have teeth both on the outer surface of the rotor and on the inner surface of the stator. Lastly, known apparatuses do not allow a continuous productive cycle, in which the products are cooled and emulsified, without idle times between one process and the other. It should be noted that different food products are characterised by different values of temperature whereat emulsion occurs optimally. In this light, the executing the cooling and aerating processes separately and at different times prevents a feedback control on the process as a whole.

SUMMARY OF THE INVENTION

An object of the present invention is to eliminate the aforesaid drawbacks and to make available an apparatus for treating food products, which enables to effect cooling and aerating processes simultaneously and continuously on said food products.

Said objects are fully achieved by the apparatus of the present invention, which is characterised by the content of the claims set out below and in particular in that it comprises:

means for injecting a fluid into a passage;

means for handling food products, to produce the emulsion of the fluid with the products by means of a substantially turbulent motion of said products within said passage.

A further object of the present invention is to make available a method for cooling and aerating substantially fluid or viscous food products, in which the cooling and aerating products take place simultaneously and continuously.

Said object is fully achieved by the method of the present invention, which is characterised by the content of the claims set out below and in particular in that it comprises the following steps:

pumping the food products through a passage;

injecting air into said passage;

moving the food products inside said passage, in such a way as to cause a turbulent motion and the emulsion of the air with the products.

BRIEF DESCRIPTION OF THE DRAWINGS

This and other characteristics shall become more readily apparent in the description that follows of a preferred embodiment, illustrated purely by way of non limiting example in the accompanying drawing tables, in which:

FIG. 1 schematically shows a lateral section view of an apparatus according to the present invention;

FIG. 2 schematically shows a frontal section view of the apparatus of FIG. 1;

FIG. 3 shows the rotor of the apparatus of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In FIG. 1, the reference number 1 designates an apparatus according to the present invention. The reference number 2 indicates a heat exchanger with cylindrical geometry, comprising a stator 3 and a rotor 4. The rotor 4 is inside the stator 3 and coaxial thereto. Between the rotor 4 and the stator 3 the exchanger 2 defines a passage 5, into which are introduced the food products to be treated. In particular, the products are thrust through the passage 5 by pumping means 6, of a substantially known kind. The rotor is set in rotation by a rotor, preferably electric, e.g. an asynchronous motor with four poles driven by an inverter, not shown in the figure. Externally to the stator 3 act cooling means 7, comprising a conduit 8 adjacent to the stator in which a cooling fluid, preferably but not necessarily constituted by water with glycol, is made to circulate. Said cooling means are able to deliver a flow rate of cooling fluid of up to 3000 1/h and they comprise insulated connecting pipes, possibly provided with bypass means. The surfaces that define the passage 5 are preferably made of stainless steel and can operate at pressures of about 25 bar. Moreover, said cooling means comprise a modulating valve 9, which allows to vary the flow rate of cooling fluid. It should be noted that the conduit 8 is hermetically isolated from the passage 5, so that the cooling fluid can in no way come in contact with the food products present in the passage 5. The maximum pressure at which the cooling conduit 8 can operate is about 10 bar. The apparatus 1 also comprises means 10 for injecting a fluid into the passage 5, so it is emulsified with the food products. This fluid is preferably, but not necessarily, constituted by air. Said injection means 10 comprise, in a preferred embodiment, a stainless steel box (not show) which acts as a buffer and is fastened to a frame (not shown) which supports the whole apparatus. The number 11 designates an automatic flow meter, i.e. a device able automatically to measure the flow rate of fluid injected into the passage 5 to be emulsified. The apparatus 1 comprises control means, not shown, able to regulate the flow rate of the fluid injected into the passage 5; said control means being operatively connected to said flow meter. In the figures, the reference number 12 designates scraping elements, associated to the rotor 4 and having a surface that, during the operation of the apparatus 1, is in substantial sliding contact with the inner surface of the stato 3, which is smooth, to prevent the food products in contact with said surface from adhering thereon by effect of the temperature gradient. Said scraping elements 12 are constituted, in a preferred but not exclusive embodiment, by fins movably associated to the rotor 4 in such a way as to be able to rotate from a first position in which they are not in contact with the stator 4 (position shown in FIG. 3) to a second position in which they are in contact with the stator 3 (position shown schematically in FIGS. 1 and 2). The scraping elements 12 move from the first to the second position by effect of the centrifugal force due to the rotation of the rotor 3. Said scraping elements 12 are made of bacteriologically inert material, preferably constituted by an odourless, non toxic synthetic resin, not containing additional glass fibres or any other additive. Moreover, the scraping elements 12 are preferably removable manually and easily replaceable. The apparatus 1 also comprises means for moving the food products inside the passage 5. Said moving means comprise, in a preferred embodiment, a plurality of teeth 13, integral with the rotor 4. Said teeth 13 substantially consist of projections that occupy a portion of the passage 5, without interfering with the inner surface of the stator 3. Said moving means, actuated by the movement of the rotor 4, cause the food products inside the passage 5 to be subjected to a turbulent motion, with consequent benefit from the viewpoint of the emulsification of the injected fluid. The apparatus 1 also comprises a temperature probe, of a substantially known kind and not shown in the figures, able to detect a temperature of the products inside the passage 5. Said temperature probe is operatively connected to a control board (not shown), which actuates the modulating valve 9 to regulate the temperature of the food products inside the passage 5. Therefore, originally, a feedback control is obtained on the temperature at which the emulsification process takes place, acting on the cooling means 7. Moreover, the described apparatus is particularly easy to wash, also automatically, thanks to the fact that the stator 3 is internally smooth. Moreover, the apparatus 1 originally enables to treat food products by cooling them and simultaneously aerating them, minimising the bulk of the apparatus, because both an exchanger and an emulsifier, not distinct from each other, are obtained in a single section. The present invention also makes available a method for cooling and aerating food products. Said method provides for the use of a heat exchanger 2 with cylindrical geometry, preferably of the type of scraping surface, substantially known. Said exchanger comprises a stator and a rotor internal to the stator and it defines a passage 5 between the stator and the rotor. Said method comprises the following steps:

pumping the food products through the passage 5;

injecting air into the passage 5;

moving the food products inside the passage 5, in such a way as to cause a turbulent motion and the emulsion of the air with the products.

Said method further comprises a step of regulating the flow rate of the air injected into said passage 5. It also comprises a step of regulating the temperature of the food products inside the passage 5. Said regulating step in turn comprises a step of measuring the temperature of the food products in the passage and a processing step, by means of an appropriate software active on a control board. Moreover, said method comprises a step of washing step of the passage 5, which in turn comprises the following steps:

cold roughing with water to be disposed of, for about 10 minutes;

washing with detergent fluid to be recirculated, for about 20 minutes at the temperature of 70° C.;

rinsing with water to be disposed of.

Said method originally enables to effect a process of aeration and cooling of food products simultaneously and continuously. In this way, the aeration process can be optimised for each type of food product, originally operating a double regulation, with feedback, of the process temperature and of the injected flow rate of fluid to be emulsified.