Abstract:
An automatically operating fermentation vat for wine-making establishments includes a main vat ( 2 ), an upper vat ( 4 ) over the main vat, an uplift pipe ( 8, 12, 10, 24, 26 ) for feeding the fermenting liquid from the bottom of the main vat to the upper vat, means ( 16, 14, 18 ) for discharging this liquid from the upper vat into the main vat so as to spray the layer of marc floating in the main vat and injector means ( 20, 32 ) associated with the uplift pipe for injecting an oxygen-containing gas into the liquid flowing through the said pipe, characterized in that the uplift pipe has a first outlet aperture ( 24 ) directing liquid into the upper vat ( 4 ) and a second outlet aperture ( 40 ) which directs the liquid into the mass of liquid in the main vat, valve means ( 22 ) being associated with the uplift pipe for selectively directing the liquid into the upper vat or into the main vat or both at the same time though the two outlet apertures.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a fermentation vat, in particular to an automatic type of vat for making red wine, which includes a main vat, an upper vat over the main vat, an uplift pipe for drawing fermenting liquid from the bottom of the main vat to the upper vat, means for releasing this liquid from the upper vat to the main vat so as to spray the layer of grape marc floating in the main vat and injector means, associated with the uplift pipe, for injecting into the liquid flowing through this pipe a flow of gas containing a suitable proportion of oxygen to oxygenate it. 
     During fermentation, and especially when making red wine, it is known that the must has to be oxygenated at various predetermined stages of fermentation. In particular, when making red wine, oxygenation helps metabolize yeasts since it makes it easier for fermentation to get under way, by increasing the growth of microbial flor and also prevents fermentation from stopping too early. In addition, oxygenating the must encourages condensation reactions between tannins and anthocians, thereby producing more complex molecules which make the colour more stable. Oxygenation also prevents the formation of unwelcome reduction agents and encourages the development of varietal aromas. 
     Patent Application TO97A000749, in the name of the present Applicant, describes a fermentation vat of the type described above, in which the must is oxygenated by aspirating ambient air and mixing it into the liquid flowing through the uplift pipe; in particular, the uplift pipe collects liquid from the bottom region of the main vat and conveys it, by means of a pump, to the upper vat, from where the oxygenated liquid is periodically released back into the main vat through a valve in the bottom of the upper vat which, when open, causes the liquid to be sprayed onto a cap of marc floating on the must/wine in the main vat. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to perfect the fermentation vat of the type described above, in order to achieve better fermentation process. 
     This object is achieved by providing a fermentation vat having the characteristics claimed in the introduction to the present description, characterised in that the aforesaid uplift pipe has a first outflow aperture feeding the liquid into the upper vat and a second outflow aperture feeding the liquid into the mass of liquid contained in the main vat, valve means being provided, in association with the uplift pipe, for selectively feeding the liquid into the upper vat or into the main vat, or into both, through the said outflow apertures. 
     Thanks to the above characteristics it is possible, at predetermined stages of the fermentation process, selectively to direct the flow of oxygenated liquid into the upper vat, and then to spray the cap of marc or, alternatively, to convey this liquid into the heart of the liquid contained in the main vat, thereby oxygenating it better and also achieving other advantages which will become apparent from the detailed description which follows. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the appended drawings: 
     FIG. 1 is a partially sectioned front view of a wine-making fermentation vat of the invention; 
     FIG. 2 is an enlarged detail of FIG. 1; 
     FIGS. 3 and 4 are schematic illustrations of a fermentation vat of the invention; 
     FIG. 5 is a longitudinally sectioned view of a valve forming part of the fermentation vat of FIG. 1; and 
     FIG. 6 is a cross-sectional view of the valve of FIG. 5, taken on the line VI—VI. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to the drawings, an automatically operating fermentation vat for wine making is generally indicated  1  and includes a main vat  2 , for containing the pressed grapes, and an upper vat  4 , positioned over the main vat and having a bottom  6 . The upper vat  4  has a valve shutter  14  engaging a central aperture  16  in the bottom  6 ; the valve shutter  14  is operated by a pneumatic or electrically-operated piston  18  which is activated by a programmable timer or by an appropriate control unit set to run the fermentation programme. 
     The uplift means include a suction pipe  8 , which is in communication with the lower portion of the vat  2  and a delivery pipe  10  which feeds the liquid into the upper vat  4 , with a pump  12  interposed between the two pipes. 
     In the embodiment shown in the drawings, the delivery pipe  10  has an associated injector  20 , shown in greater detail in FIG. 2, for injecting a flow of ambient air into the liquid flowing through the uplift pipe in order to oxygenate it. Downstream of the injector  20  there is a valve  22  in the delivery pipe  10  so as to be in communication with a pipe  24  which introduces the liquid into the upper vat  4  and with a pipe  26  for introducing the liquid into the mass of fermenting liquid through an outflow aperture  40 . 
     The valve  22  can be manual but is preferably a servo-operated automatic valve which can be controlled by a control unit programmed to control the fermentation cycle. 
     Typically, the valve  22  is a three-way valve provided to feed the liquid selectively either into the vat  4  through the pipe  24  or into the vat  2  through the pipe  26 , or to stop the flow of liquid through the uplift pipe. 
     A preferred embodiment of the valve  22  is shown in FIGS. 5 and 6; this valve has a hollow, cylindrical body  51 , with two circular outlet apertures  52   a ,  52   b  in its lateral surface  52 . The radial axes perpendicular to the axis of symmetry of the body  51  and which pass through the centres of the circular apertures  52   a ,  52   b,  preferably form a 90° angle. 
     Connector unions  62   a ,  62   b,  with threaded flanges for engaging pipes on their free ends  63   a,    63   b,  are welded to the lateral surface  52 , coaxially with the apertures  52   a ,  52   b.  The connector unions  62   a ,  62   b  are connected to the pipe  24  and the pipe  26  respectively by means of the aforesaid flanges. 
     The body  51  also has a closed end  51   a,  with a lid  71  which is screwed to the body, and an open end  51   b  with an inlet aperture  51   c.  An inlet union  72  is welded to the inlet aperture  51   c,  with a threaded flange on its free end for the connection of pipes. The inlet union  72  is connected to the delivery pipe  10  by this flange. 
     A substantially cylindrical valve shutter  80  is housed coaxially inside the body  51 , so that it can rotate sealably therein. The valve shutter  80  includes a cylindrical casing  81 , open at the site of the inlet aperture  51   c,  and a connector element  83 . The casing  81  has an exit through-hole  82  in its lateral surface and can be rotated selectively so that the hole  82  is coaxial with one of the circular outlet holes  52   a ,  52   b.  A substantially cylindrical connector element  83  is securely fixed inside the casing  81 , with its connecting portion  83   a  shaped so as to form a 90° elbow joint between the inlet aperture  51   c  and one of the outlet apertures  52   a ,  52   b.  With such a valve shutter, the liquid can enter the valve in a regular flow, without creating excessive turbulence or pooling. 
     The valve  22  is operated and controlled by a control shaft (not shown). This shaft passes through a hole  71   a  in the centre of the cover  71  and engages in a grooved cavity  81   a  in the closed end of the casing  81 , in such a way that rotation of the shaft causes the valve shutter  80  to rotate as well. 
     It is possible for the valve  22  to have an additional open position in which the liquid is fed to the two vats  2  and  4 . A preferred embodiment of the injector  20  is shown in FIG. 2; this injector includes a nozzle  28 , inside the delivery pipe  10 , with a restricted section  30 . Near the restricted section  30 , the pipe  10  is in communication with an air-suction pipe  32 . The pipe  32  has an associated manual or servo-operated valve  34  for intercepting and regulating the flow of air which is aspirated. It has been found that an injector of the type shown in FIG. 2 gives the best results in terms of volume of air aspirated, thereby avoiding any risk of blockages due to solids suspended in the liquid flowing through the uplift pipe. 
     It is clear, however, that the invention should not be seen as limited to injector means of the type shown. Venturi type injectors, such as those described in the Patent Application TO97A000749 by the present Applicant, could be used, or any type of injector or ejector or jet pump, operable to ensure that the liquid is efficiently oxygenated during the uplift cycle. The scope of the invention also extends to injection of oxygen either into the delivery pipe  10  as described, or into the suction pipe  8  or through an inlet aperture in the pump  12 . The injection of oxygen is preferably carried out upstream of the valve means  22 . 
     Equally, although the drawings show the pipe  26  as a semi-immersed tube, with its free end in the liquid in the main vat  2 , it is clear that the invention is not limited to this configuration. For example, the liquid could be conveyed to the lower vat  2  by means of a tube entering the vat through one side, as shown schematically in FIGS. 3 and 4, for example; it is clear that, with reference to the diagrams of FIGS. 3 and 4, the injector means, indicated  20 , should be located in the uplift pipe. 
     The fermentation vat preferably includes sensor means  36 , operable to monitor a parameter in the fermenting liquid which would indicate how the fermentation is progressing or the degree of oxygenation and to emit a signal indicating this parameter to a control unit  38 , programmed to control the opening or closing of the valve means  34  associated with the injector, in dependence on the signal received from the sensor means. This parameter indicating the progress of fermentation can be the density of the liquid or a Redox potentiometer, able to measure the level of oxidation of the liquid. The control unit  38  can form part of the overall control unit of the wine-making process, which controls temperature, operation of the uplift cycle and release of the liquid from the upper vat to the lower vat, as well as operation of solenoid valve  22 . 
     The structural characteristics of the fermentation vat of the invention make it possible to improve various aspects of the fermentation process. First, during the first phases of the operating cycle, the main vat is filled to a predetermined level with pressed grapes; the so-called “cap” of marc then forms in the upper portion of the vat. In this initial stage, the fermentation vat of the invention makes it possible to run uplift cycles during which liquid is collected from the bottom of the vat  2 , oxygenated by aspirated ambient air and returned to the main vat through the tube  26  which opens into the middle of the liquid. This operation was found to generate an advantageous flotation effect, which led to a speedier separation of the marc cap. The turbulence caused by the flow of oxygenated liquid into the mass of liquid substantially improves the oxygenation effect and also acts to remove carbon dioxide which is beginning to form in the fermenting mass. 
     This speedy formation of the cap means that uplift cycles can be started sooner, initially along with oxygenation, the valve  22  being put into communication with the tube  24 , so that the oxygenated liquid moves up into the upper vat  4 . In these first uplift cycles, the liquid conveyed into the upper vat  4  is discharged through the aperture  16 , with the valve shutter open  14 , thereby spraying a jet onto the cap. This operation can be followed by a period of maceration, without oxygenation, during which cycles of uplift and spraying of the cap can be carried out with the valve  34  closed, which cuts off the intake pipe  32  of the injector  28 . Additional must oxygenation cycles can be carried out at the discretion of the wine maker either during the stage of tumultuous fermentation and in the final stages. 
     It is also advantageous to carry out further oxygenation operations, channelling the flow of oxygenated liquid through the pipe  26  directly into the heart of the mass contained in the main vat, at the end of the fermentation process, when the cap separation effect created by the generation of carbon dioxide is wearing off. Under these conditions, the directing of a flow of oxygenated liquid through the tube  26  makes it possible to cause the cap to float up again, thereby facilitating the run-off operation and improving the yield of quality must. 
     Generally speaking, the oxygenation process, carried out by directing oxygenated liquid into the heart of the liquid in the main vat  2 , makes it possible substantially to improve the oxygen yield, increasing the percentage of oxygen contained in the air intake which is dissolved in the must, compared to that found when the liquid is carried to the upper vat  4  through the uplift pipe. 
     In view of the operating characteristics described above, and of the advantages arising therefrom, a further object of this invention is also to provide a fermentation method, in particular for red wine, to be carried out in a vat having the characteristics described in the above description and in the Claims which follow, and which includes the steps of: 
     carrying out cycles for oxygenating the liquid in the main vat by drawing off liquid from the bottom of the said vat, aspirating ambient air and mixing it with the flow of liquid and returning the oxygenated liquid to the mass of liquid in the main vat, and 
     carrying out cycles for oxygenating the liquid in the main vat by drawing off liquid from the bottom of the said vat, aspirating ambient air and mixing it with the flow of liquid, conveying the oxygenated liquid to the upper vat and discharging this liquid from there into the main vat, thereby spraying the marc floating on the liquid contained therein. 
     It is clear that an operator can programme these operations by means of the control unit which controls the automatic operation of the fermentation vat.