DEVICE AND METHOD FOR COLD THICKENING OF MUST
1. TECHNICAL FIELD TO WHICH THE INVENTION RELATES
The present invention relates to the field of wine industry and may be, according to the International Patent Classification (IPC7), classified in C12G1/02.
2. TECHNICAL PROBLEM TO BE SOLVED
In the practice so far, when owing to bad weather conditions, must haven't contained enough sugar and had to be sweetened, or when dessert wines have been prepared, the problem has been solved by adding sugar - saccharose, being permitted under our relevant law. This wouldn't be acceptable in the European Union where we would export our wine products.
Under the EU regulations, the addition of saccharose to quality wines is not permitted. The increase of sugar is permitted only by the addition of thickened must that should be prepared using exclusively the same must designed for the production of the wine. The same method may be used for the preparation of quality wines, similar to the so-called "frozen wines".
The technical problem to be solved is a design of new apparatus and method for cold thickening of must without saccharose addition.
3. STATE OF THE ART
The state of the art includes the technique of thickening the must by boiling it at 100°C and under the atmospheric pressure. The deficiency of this process is the modification of organoleptic features of wines thus prepared, such as a caramel scent and the like. The second process used is boiling at lower pressure, the vapor being vacuumed by vacuum pumps, but I don't know whether this process is used in the Republic of Croatia.
4. DISCLOSURE OF THE INVENTION
The essence of the invention is the continuous thickening of must at lower temperatures. The apparatus allows the must thickening even at temperatures below 15°C. The optimal working regime ranges from 20°C to 50°C. The already constructed and tested apparatus, of a volume less than 100 dm3 (0,1 m3), and nominal electromotive driving force of less than 3kW, allows 250 liters of water to be separated from the treated must within 24 hours, without any
necessity of the human control. Thus thickened must may increase for 2% the amount of the basic sugar of 2100 liters of the same must (e.g. from 17%> it can be increased to 19%>). A significant additional characteristic of the apparatus is its relatively low price, being such owing to the possibility of building in it serially produced machines and fittings.
5. SHORT DESCRIPTION OF THE DRAWINGS
Fig. 1 Schematic representation of the apparatus Fig. 2 Vacuum-column (axial cross-section) Fig. 3 Bottom of the vacuum-column (transversal cross-section)
1 fresh must
2 suction pipe
3 filter
4 level regulator
5 vacuum column
6 steam pipeline
7 water pre-cooler
8 vapor condenser
9 condensate
10 non-return valve
11 vacuum pump
12 drain pipe
13 circul ation pump
14 overflow valve
15 must heater
16 nozzle
17 thickened must
18 compressor
19 expander
20 pot
21 spiral ribs
22 top of the column
23 labyrinths
24 circular ring
25 narrow slot
26 lateral opening
Fig. 1 shows the way in which fresh must (1) is sucked in a vacuum-column (5) through a suction pipe (2), a filter (3) and a level regulator. On the bottom of the column there is an
outlet pipe, through which must flows to a circulation pump (13), then is pressed towards a divisional fitting with overflow valve (14), where the main stream flows through a must heater (15) and tangentially set nozzle (16) stream into a vacuum-column (5), while a smaller portion (approx. 5%), depending of the must thickness, flows, through an overflow valve (14) to a container (17). On the top of the column (5) the air and the vapor are lead through a water pre-cooler (7), a vapor condenser (8) and small condensate (9) collector to the vacuum pump (11), to be drained through a drain pipe (12). Compressor (18) presses cooling medium into exchanger (15) where it transfers the condensation heat to the must, then, through an attenuator (19), it expands in the vapor condenser (8), where it takes the heat from the condensed vapor, and wherefrom it is sucked by the compressor (18). Both heat circular flows can work continually, i.e. the pump (13) and the compressor (18) may work continually, if necessary. The vacuum pump (11) is put into operation at intervals, depending on the accumulated condensate (9) and the increase of the pressure in the vacuum system. Fig. 2 and 3 show the vacuum column (5) that sucks the flowing must through a nozzle (16) which through a directed narrow and flat slot (25), in a tangential flow a little bit downwards and in a high velocity showers the inner cylindrical wall of the column, so that the must in a tin layer spirally flows towards the bottom of the column, releasing the vapor and partially retaining its kinetic energy, which is, at the bottom, partially transformed, by spiral ribs (21), into potential energy, to facilitate its flow towards circulation pump (13) and to decrease the cavitation on the pump rotor. The level regulator (4) spills the fresh must (1) into a pot (20) and doses it, through lateral openings (26), into the circular flow system. The top of the column (22) is dismountable and the sealing is made by a circular ring (24). In the very dome at the top of the column (22) there are labyrinth rings (23) to prevent the drops of the circulating must to spill out.
6. DETAILED DESCRIPTION OF ONE EMBODIMENT OF THE INVENTION
The process of thickening the must according to the invention shall be carried out as follows: a) Immediately after harvesting and pressing grapes, a selected quantity (e.g. 5%) of the same fresh must (1) has to be strained in a special container free of mechanical dirt, and after that a suction pipe (2) has to be put in it.
b) A vacuum pump (11) has to be put into operation so that the created underpressure start suctioning fresh must through a suction pipe (2) into a vacuum column (5) across the filter
(3). c) Put into operation a compressor (18) of the cooling medium to warm up the heating circular flow of the cooling medium and wait that the temperature of the cooling medium on its return to the compressor rises above 0°C. This can be seen from the outer surface of the return pipe which is immediately after the start covered with hoar frost, and when it is melted we know that the temperature has risen above 0°C. d) Put into operation a circulation pump (13) to put must into circulation. e) The drainpipe of the overflow valve (14) has to be immersed in the container for thickened must (17). When the vacuum pump (11) sucks the must into a column (5), and then sucks the air to achieve the underpressure that is selected according to the desired temperature of water evaporation (this is determined by the selection of the required underpressure, e. g. 80 millibars), the vacuum pump is automatically put out of operation, and the non-return valve (10) prevents the air from returning back to the vacuum system. f) When a part of the condensate is collected in the collector and the pressure is decreased (the underpressure is increased), the vacuum pump (11) is by means of pressostat, automatically put into operation again (as in a household well pump). g) After a certain time of the compressor (18) being in operation, when the cooling medium achieves the desired temperature, depending on the evaporation temperature, electromagnetic valve is automatically opened to dose cooling water for pre-cooling of water vapor to balance the surplus of the heat generated by the compressor, and to maintain stable both heating circular processes: 1. the process includes heating of the must to be thickened along with vacuuming at low temperatures, 2. the process includes compression and expansion of the cooling media, h) After a while, when the must is thickened, i.e. when its specific thickness increases and its viscosity is decreased respectively, the resistance to circulation is increased, and pressure in the pressure pipeline is increased respectively, causing the overflow valve (14) to open and to let the portion of the circular flow of already thicken must (17) flow out into a container.
This process allows the continuous thickening of the must that may last as long as there is must, electricity and water. In the case of discontinuance of the operation, the thickened must prepared according to this process may, after the operation is resumed, achieve the primary quality as soon as the same adjusted temperature and pressure parameters are achieved in both circular processes.
7. THE METHOD OF APPLYING THE INVENTION
To manufacture the apparatus according to the invention one has to have an average knowledge and skill in mechanical engineering, and for its application one have to follow the operational instructions.
This apparatus doesn't produce any bad effects to the environment, because it doesn't pollute the environment and while used doesn't produce any hazardous waste. Therefore, it may be considered as ecologically acceptable. Having a total mass of approx. 100 kg the apparatus is designed as portable. Such a portable apparatus shall satisfy the treatment of must in a quantity of 1 wagon/day (approx. 6000 1/day). For the treatment of larger quantities of must it shall be necessary and possible to construct an apparatus of a stationary type, of bigger dimensions and therefore, if necessary, design assemblies and fittings of bigger capacity. A significant characteristic of the manner of application of this apparatus according to the invention is its continuous operation.
Apart from being applied for the preparation of must, this apparatus may also be applied to other similar products: the invention allows the cool thickening of various fruit juices, and other beverages such as milk and the like, without using preservative(s). The apparatus is designed in such a way that a serial production of its portable version is possible at a relatively low price, making it available to the majority of our vine growers.