A method and device for the production of coagulated products

Abstract: In a method for the production of coagulated products, in particular food products obtained by the coagulation of dairy and similar products, the starting material coagulation step involves the heating of the material itself at least in part by indirect means. Preferably, such indirect heating is obtained by passing steam through a jacket or similar hollow space shrouding the coagulation container. The degree of coagulation of the finished product may be controlled by the regulation of the quantity of heat transmitted directly or indirectly to the starting material.

Description: The present invention concerns a method and a device for the production of coagulated products. More detailedly the present invention concerns a method and a device for the production of food products such as, for example, dairy products like "ricotta" (cottage cheese) and similar products, obtained by a coagulation process which requires a simultaneous heating of the starting materials. Plants for the continuous production of cottage cheese are well known, which comprise means for pre-treatment of the starting serum and for preheating to a first temperature, lower than the coagulation temperature, as well as means for coagulating the pre-treated and preheated serum so as to obtain the coagulated product in a continuous flow. This coagulation means consist of a conical-sectioned vessel with the point downwards, into which the pre-treated serum is fed together with an acidic coagulating solution, and means to raise the temperature to that required for coagulation. Since it is necessary to further raise the temperature of the mixture of serum and acidic coagulating solution to achieve coagulation, there are nozzles in the coagulation vessel to inject steam directly into the acidified serum. The coagulated "ricotta" (cottage cheese) thus obtained floats to the surface of the serum from whence it is removed to be packaged. The main drawback of this plant is its lack of flexibility. The ricotta (cottage cheese) obtained with this type of plant has a "hard" consistency and forms "grainy" coagulates. It has been ascertained that this consistency of the coagulated products is due to the degree of heating applied to the product in the coagulation vessel. A regulation of the quantity of the steam inside the vessel does not succeed in producing a sufficiently soft "pasty" product. Furthermore, such types of plant are suitable only for the production of ricotta (cottage cheese) products; they require substantial changes to be used for the production of other dairy products, such as "mascarpone", or other types of cheese. Indirect heating of acidified milk to prepare standard cheese (but not ricotta) is known in the art, e.g. from Speer Milchbereitung (1977), 302 and from Cheese and Fermented Milk Foods (1978), 97, where steam jackets are disclosed. According to the teachings of these documents direct heating should always be avoided. Molder et al., Milchwissenschaft, 44 (1989) n. 11, 673-676, disclose a plant and a process for continuous production of ricotta. According to this document, ricotta is obtained by indirectly heating a milk derivative in two steps, and by passing it through small diameter tubes. As for previously disclosed plants, also this plant is suitable to prepare ricotta only. Moreover, this plant has the drawback of being expensive to build and difficult to operate and to clean. There is thus the need for a method and device for the controlled production of coagulated products by the regulation of the coagulation temperature, which can be used for producing various kinds of coagulated products. An object of the present invention is to overcome the problems listed above and to produce a method and a device for the controlled and flexible production of coagulated food products obtained by the coagulation of dairy or similar products. This object is achieved by a method and a device which allow to very precisely regulate the quantity of heat supplied to the material to be coagulated during the coagulation phase, thus providing a controlled coagulation and enabling the production of various types of dairy products. In greater detail, the invention concerns a method for the production of coagulated products - ricotta in particular - of the type in which the coagulation phase of starting material involves the heating of the material itself, according to claim 9. The invention further concerns a device for the production of coagulated products - ricotta in particular - according to claim 1. The invention will now be described in greater detail with reference to the enclosed drawings which are given as an illustrative but not limitative example and wherein: fig.1 is a cross section of the device according to the invention; fig.2 is an enlarged view of a detail of the embodiment of fig.1; fig.3 is a schematic plan of the device shown in the preceding figures. As it has been already stated, the principle of the invention provides for the supply of the coagulation vessel for the starting material with means for heating the product at least in part by an indirect manner. Preferably, such indirect heating is obtained by passing steam through a jacket or some similar hollow space shrouding the coagulation container. It has been surprisingly discovered that if the starting temperature during the coagulation phase is brought to the desired level by indirect heating, the coagulated products thus obtained are highly hydrated and show a very soft "pasty" consistency. To better control the final consistency of the coagulated products, a preferred embodiment would include direct heating means of the traditional type to obtain the degree of consistency suited to the type of product being processed. It should be noted here that although the following specification refers to a plant for the production of ricotta (cottage cheese), the principle of the invention is applicable to any type of starting material which is coagulated by a method requiring the application of heat to obtain such coagulation. With reference to fig.1, the coagulation vessel 1 is supplied with a jacket 2 enshrouding its walls and within which a heating liquid, preferably steam, is supplied and made to circulate. Such steam is generally supplied to the jacket or shroud 2 by nozzles 3 at the base of the jacket, so that the steam rises through the condensate formed within the jacket 2, thus giving a uniform distribution of the heat along the walls of the vessel 1. Externally, the jacket is covered by an insulation layer to insulate it from the enviroument. To prevent the product from adhering to the walls 4 of the vessel 1, the device according to the present invention is fitted with a reel 6 positioned on the vertical axis of the vessel 1, and supplied with a plurality of arms 7, 7′and 7″, supporting a corresponding plurality of sweeping scrapers 8 in contact with the surface of the vessel walls 4. Fig. 3 shows a schematic plan view from above of the layout of the sweep scrapers with respect to the reel 6. As can be seen from figs 1 and 3, the arms of the scrapers are positioned at different heights along the reel 6 and are thus of different lengths. It may also be seen that the arms 7 are arranged at angles of 120 degrees and are the longest, since they are connected to the upper end of the reel 6. Similarly, the arms 7′ and 7″ are arranged at angles of 120 degrees and are of decreasing length depending on their position on the reel 6. The reel 6 is driven by a gear train (not shown) or similar device which rotates the reel 6 and the scrapers connected to it at a constant speed. To prevent a negative effect on the coagulation reaction of the product in the vessel, this speed is about 2 rpm. As it can better be seen from fig.2, which shows a cross-section of the device along the A - A line of fig.3, besides the means for indirectly heating the starting material - through the jacket 2 - also means for directly heating the starting material in the traditional manner are foreseen. Such means consist of a steam feed pipe 9 and a nozzle 10 in correspondence with the lower end of the vessel 1. Above the steam inlet nozzle, a similar though smaller nozzle 11 is connected to a feed pipe 12 through which the coagulating mixture is supplied to the vessel. Where the product is ricotta (cottage cheese), said mixture is an acidic solution; but it could be any type of coagulant, depending on the starting material. Inside the vessel there are sensors (not shown) or similar means to detect the temperature during the coagulation phase. The device is fitted with simple means of regulation, such as valves or the like, to regulate the quantity of heat admitted both directly and indirectly to the material to coagulate. By suitably controlling the steam quantities fed to the jacket 2 or directly blown onto the material through the nozzle 10, the degree of hydration of the coagulated products can be made more or less, according to the ratio between direct and indirect heat. If the heating is predominantly indirect, the coagulated product is very hydrated and "soft"; a prevalent direct heating produces a "harder" product. During the procedure, the material to be coagulated (pre-heated and pre-treated milk serum in the case of ricotta (cottage cheese) is admitted to the lower end of vessel 1 through a feed pipe 13. Simultaneously, steam is admitted by the nozzles 3 to the jacket 2, and/or through the feed pipe 9 and the nozzles 10 directly to the interior of the vessel. The admission of a coagulation mixture, e.g. an acidic solution in the case of ricotta (cottage cheese), along the line 12 and the nozzle 11, together with the raising of the temperature of the starting material, initiates the coagulation of the material itself with the formation of agglomerates, whose hydration and thus softness and pastiness depends on the ratio between the quantity of steam entering the jacket through nozzle 3 and the quantity passing through nozzle 10. To avoid the coagulated products from adhering to the walls 4 of the vessel 1, the reel 6 with the attached scrapers is rotated at a predetermined speed, of the order of 2 rpm. As it has been already remarked, this coagulation device is particularly suited for a plant for the production of ricotta (cottage cheese), containing therefore, together with the device according to the present invention, also means for the pre-treatment of the starting material, mixing it with any additives and, upstream of its admission to the coagulation vessel 1, means for pre-heating the pre-treated starting material, and, downstream of the device according to the present invention, means to remove the coagulated products and despatch the coagulated ricotta (cottage cheese) as obtained inside the vessel 1 to a packaging plant. From above, it is evident that the coagulation procedure can be controlled by the device according to the present invention in a very simple but at the same time efficient way, thus enabling it to be used not only for the production of ricotta (cottage cheese), but also for the production of other dairy or coagulated products in which the coagulation phase requires the heating of the starting materials.

Claims: A device for preparing ricotta from a starting material of the type comprising a coagulation vessel (1), means to separately feeding to said vessel a coagulating mixture and said starting material, and means for heating said starting material, characterized in that said heating means comprises indirect heating means arranged around the said coagulation vessel, and direct heating means provided within said vessel. A device according to claim 1, wherein said direct heating means comprises a nozzle (10) positioned in said vessel adjacent to said starting material feed pipe (13) and connected to a source of steam. A device according to claim 1 or 2, wherein said indirect heating means comprise a jacket (2) surrounding said vessel (1) and housing a nozzle (3) connected to a source of steam. A device according to any previous claim, wherein said coagulating mixture feeding means comprises a feeding nozzle (11) positioned within said vessel (1), adjacent to said steam nozzle (10). A device according to any claim 1 to 4, characterized in that it further comprises means for scraping the internal surfaces (4) of said vessel (1). A device according to claim 5, characterized in that said scraping means comprises rotating reel (6) with a plurality of scrapers (8) supported by arms (7-7''). A device according to claim 6, characterized in that said reel (6) is rotated by a geared motor at a speed of about two revolutions per minute. A device according to any previous claim, further comprising control means for regulating the amount of heat respectively fed by said direct (10) and indirect (3) heating means, according to the required degree of coagulation of said milk derivative. A method for the production of ricotta product by coagulation of a starting material, the coagulation of said starting material involving its heating and acidification in a coagulation vessel, characterized in controlling said coagulation step by heating said starting material both directly and indirectly. A method according to claim 9, wherein indirect heating is carried out by feeding steam to a jacket (2) or similar hollow space arranged around the coagulation vessel (1). A method according to claim 9, wherein said direct heating is carried out by feeding steam directly to said starting material within said coagulation vessel (1). A method according to claims 9 to 11, wherein the internal surfaces (4) of said coagulation vessel (1) are scraped during said heating and coagulation phase. A method according to any previous claim, wherein the amount of steam fed to said direct (10) and indirect (3) heating means is controlled according to required coagulation degree. A method according to any previous claim, further comprising the phases of pre-heating said starting material and introducing additives before the coagulation phase. A plant for the continuous production of ricotta, characterized in that it comprises a coagulation device according to any claim 1 to 8. A plant according to claim 15, characterized in that it comprises means for pre-heating and carrying-out any addition of additives to the starting material upstream said coagulation device, as well as means for collecting ricotta downstream said device.

Inventors: ROTA ALBERTO, ROTA, ALBERTO
Applicants: ROTA GUIDO SRL, ROTA GUIDO S.R.L.
Application year: 1990
Main classification: A23C19
IPC codes: A01J25, A23C19