Abstract:
A process is disclosed for reducing alcohol in a fermented beverage without heat damage and without degrading the original flavor profile of the fermented beverage. The process generally includes the steps of: (i) removing aromatics from the wine; (ii) removing alcohol from the wine; (iii) refluxing a portion of the alcohol removed from the wine to increase the alcohol concentration of the alcohol vapor and return at least a portion of the condensed/recovered water to the wine; and (iv) condensing the aromatics removed from the wine and returning at least a portion thereof to the wine.

Description:
BACKGROUND 
     The present invention relates to a process and apparatus for the reduction of alcohol in fermented beverages. More particularly, the present invention relates to a process and apparatus for reducing the alcohol (i.e. ethanol) content of wine. 
     The challenge when reducing the alcohol content of wine is to:
     1. not cause heat damage to the wine;   2. cause minimal water loss from the wine during the alcohol reduction process; and   3. retain in, or return to the wine as much aromatics and flavour components as possible.   

     In most wine producing countries, it is illegal to dilute wine with water. It is generally not illegal to adjust the taste of wine by removing constituents like acids. Except for a few countries, it is generally not illegal to remove alcohol from wine. It has become standard practice in hot climates, where grapes develop high sugar levels (and therefore, high alcohol content), to practise alcohol reduction techniques on the wine produced. 
     A variety of processes for removing select component parts from beverages are known. For example, evaporation technology is generally used to remove water from fruit juice and thereby concentrate the fruit juice. However, no feedback loop to re-introduce water evaporated from the feedstock fruit juice back into the evaporation chamber exists, causing the feedstock fruit juice to concentrate, and the operating temperature in the evaporation chamber consequently to rise. Drawbacks of evaporation chambers are that they result in significant water loss from the feedstock juice and their operating temperatures would cause heat damage to a wine feedstock. 
     Other technologies directed specifically at the removal of alcohol are also known. An example is the membrane processes, which extracts an alcohol-rich permeate stream from wine under pressure. Drawbacks of this process are that: the equipment is expensive; the membranes have a limited lifespan; and the high pressure required makes this process energy intensive. A further example is the spinning cone column used by ConeTech, in which the wine is subjected to low-pressure heating in a column equipped with fast-rotating cones to drive off a portion of the alcohol. A drawback of this process is that, in addition to removing alcohol, many of the flavour components are also removed from the wine and need to be recovered and added back to the wine if the original flavour profile of the wine is to be retained. Another drawback is the inability of the ConeTech technology to concentrate the alcohol stream removed from the wine, resulting in undesirable loss of water from the de-alcoholised wine. A further drawback of the ConeTech technology is that its column includes many internal moving parts rotating at high speed, making the equipment expensive and energy and maintenance intensive. 
     The process and apparatus according to the present invention aims to address the above drawbacks and challenges. 
     SUMMARY OF THE INVENTION 
     According to a first aspect of the present invention there is provided a process for reducing alcohol in a fermented beverage that includes the steps of:
         pre-heating a fermented beverage feedstock to a temperature between 40° C. and 60° C.;   introducing the pre-heated fermented beverage feedstock into the upper section of a first distillation column having an operating pressure between 5 kPa and 50 kPa and an operating temperature between 40° C. and 80° C.;   subjecting the fermented beverage feedstock, as it flows down the first distillation column, to alcohol vapour rising up the first distillation column, thereby stripping aromatics from the fermented beverage feedstock to yield an aromatic vapour;   passing the aromatic vapour through a first condenser to condense the aromatics from the aromatic vapour;   discharging the fermented beverage from the first distillation column;   introducing the fermented beverage discharged from the first distillation column into the upper section of a second distillation column having an operating pressure between 5 kPa and 50 kPa and an operating temperature between 45° C. and 85° C.;   subjecting the fermented beverage, as it flows down the second distillation column, to steam rising up the second distillation column, thereby stripping alcohol from the fermented beverage to yield an alcohol vapour;   splitting the alcohol vapour exiting the second distillation column into at least two streams, and feeding: (i) a first stream of alcohol vapour into the bottom section of the first distillation column; and (ii) a second stream of alcohol vapour into a rectifier;   refluxing the second stream of alcohol vapour in the rectifier to increase its alcohol concentration;   passing the refluxed alcohol vapour exiting the rectifier through a second condenser to condense the alcohol from the alcohol vapour;   returning at least a portion of the liquid condensed in the rectifier into the upper section of the second distillation column; and   discharging the fermented beverage from the second distillation column and returning at least a portion of the condensed aromatics thereto.       

     The process may include the step of subjecting at least a portion of the aromatics exiting the first condenser to a membrane separation process to remove a portion of the alcohol therefrom. And, at least a portion of the aromatics that has passed through the membrane separation process may be returned to the fermented beverage discharged from the second distillation column. 
     Typically, the steam rising up the second distillation column is a low concentration alcohol vapour between 1% and 50% ABV. 
     Preferably, the process includes the step of passing the vapours exiting the first and/or second condensers through a scrubber column. More preferably, at least a portion of the fermented beverage that has been discharged from the second distillation column is fed through the scrubber column to absorb aromatics from the vapours. 
     Typically, at least a portion of the fermented beverage with absorbed aromatics exiting the scrubber column is returned to the fermented beverage discharged from the second distillation column. 
     Generally, the fermented beverage is wine. 
     Preferably, the wine discharged from the second distillation column has an alcohol concentration greater than 1% alcohol-by-volume (ABV). More preferably, the wine discharged from the second distillation column has an alcohol concentration greater than 0.5% ABV. 
     Typically, the wine discharged from the second distillation column with aromatics re-introduced is mixed with fermented beverage feedstock and stored in a tank, packaged or bottled for human consumption. 
     According to a second aspect of the present invention there is provided apparatus for reducing alcohol in a fermented beverage using the process described above. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A preferred embodiment of the invention will now be described in more detail, by way of example only, with reference to the accompanying drawing in which: 
         FIG. 1  is a schematic diagram of a plant operating the process according to a preferred embodiment of the invention. 
     
    
    
     In this specification, “alcohol vapour” means vapour that includes both alcohol and water components. The term is not limited to pure alcohol vapour. Furthermore, all pressures mentioned in this specification are “absolute pressures”. 
     DESCRIPTION OF THE INVENTION 
     With reference to the  FIG. 1 , a process for reducing alcohol in a fermented beverage  10 , such as wine, according to a preferred embodiment of the invention includes the steps of: (i) removing aromatics from the wine; (ii) removing alcohol from the wine; (iii) refluxing a portion of the alcohol removed from the wine to increase the alcohol concentration of the alcohol vapour and return at least a portion of the condensed/recovered water to the wine; and (iv) condensing the aromatics removed from the wine and returning at least a portion thereof to the wine. 
     The process  10  starts by passing wine feedstock  12  through a pre-heater  14  to pre-heat the wine feedstock  12  to a temperature between 40° C. and 60° C. The pre-heater  14  transfers heat from de-alcoholised wine  16  that has previously passed through the process  10 . 
     The pre-heated wine feedstock  12  is then introduced into a first distillation column  18  through an inlet at or near the top of the column and permitted to flow under gravity to the bottom of the column  18 . At or near the bottom of the first distillation column  18  is an inlet for alcohol vapour  20  to enter and rise up the column  18  to a vapour outlet near the top of the column  18 . The counter-flow of the wine feedstock  12  travelling down the column  18  and the alcohol vapour  20  rising up the column  18  causes aromatics (together with a small amount of alcohol and water) to be stripped from the wine feedstock  12  to yield an aromatic vapour  22 . The degree of stripping of aromatics from the wine feedstock  12  is determined by the rate of flow of alcohol vapour  20  through the first distillation column  18 , as controlled by a valve (not shown) in either the alcohol vapour inlet or the vapour outlet. The interior of the first distillation column  18  typically includes random or structured packing or trays (not shown) to encourage aromatic stripping of the wine feedstock  12  by the alcohol vapour  20 . 
     To prevent heat damage to the wine  12 , the first distillation column  18  operates at a pressure between 5 kPa and 50 kPa and a temperature between 40° C. and 80° C.—the temperature being dependent on the pressure in the first distillation column. 
     The de-aromatized wine collected at the bottom of the first distillation column  18  is discharged from the column  18  and introduced into a second distillation column  24  through an inlet at or near the top of the second distillation column  24  and permitted to flow under gravity to the bottom of the column  24 . At or near the bottom of the second distillation column  24  is an inlet for low pressure steam or low concentration alcohol vapour (i.e. between 1% and 50% alcohol-by-volume (ABV))  26  to enter and rise up the column  24  to a vapour outlet near the top of the column  24 . The counter-flow of the de-aromatized wine  12  travelling down the column  24  and the steam/low-concentration alcohol vapour  26  rising up the column  24  causes alcohol (together with some water and residual aromatics) to be stripped from the de-aromatized wine  12  to yield an alcohol vapour stream  20  having an alcohol concentration typically between 40% to 70% ABV (dependent on the alcohol concentration of the wine feedstock  12 ). The degree of stripping of alcohol from the de-aromatized wine  12  is determined by the rate of flow of steam/low-concentration alcohol vapour  26  through the second distillation column  24 . The steam/low-concentration alcohol vapour  26  is generated by partial vaporisation of a portion of the de-alcoholised wine  16  in the base of the second distillation column  24 . This enables the production of wine with a varying degree of alcohol depletion exiting the bottom of the second distillation column  24 . The interior of the second distillation column  24  typically includes random or structured packing or trays (not shown) to encourage alcohol stripping of the de-aromatized wine  12  by the steam/low concentration alcohol vapour  26 . 
     To prevent heat damage to the wine  12 , the second distillation column  24  operates at a pressure between 5 kPa and 50 kPa and a temperature between 45° C. and 85° C. 
     The alcohol vapour  20  exiting the second distillation column  24  is split into two streams. A first stream  20  is fed into the first distillation column  18  via the alcohol vapour inlet and a second stream  20  is fed into a rectifier  26 . While in the rectifier  26 , the second stream of alcohol vapour  20  encounters refluxed alcohol liquid, continually condensing and evaporating until the alcohol concentration of the alcohol vapour  20  within the rectifier  26  reaches typically 80% to 95% ABV. The reflux process increases the alcohol content of the alcohol vapour  20  by condensing water therefrom. This water  28  (with an alcohol component) is collected at the bottom of the rectifier  26  and returned to the top of the second distillation column  24 . In so doing, the water  28  condensed from the alcohol vapour  20  in the rectifier  26  is returned to the de-aromatized wine  12  in the second distillation column  24 . 
     The alcohol vapour  30  exiting the rectifier  26  is passed through a second condenser  32  that uses a cold utility, cooling water, chilled water, or glycol to condense the alcohol therefrom, which is stored in a tank  34 . 
     De-alcoholised wine  16  discharged from the second distillation column  24  has an alcohol concentration greater than 1% ABV or, in some instances, 0.5% ABV. This de-alcoholised wine  16  is returned to the pre-heater  14  to transfer heat to wine feedstock  12  and thereby reduce the temperature of the de-alcoholised wine  16  to between 20° C. and 40° C., depending on the temperature of the wine feedstock  12 . 
     The aromatic vapour  22  exiting the first distillation chamber  18  is passed through a first condenser  36  (which typically operates at a temperature 1 to 5° C. higher than that of the second condenser  32 ) to condense the aromatics from the aromatic vapour  22 , which condensed aromatics  38  (or a portion thereof) are then returned to the de-alcoholised wine  16 . 
     The vapour  40  exiting the first and second condensers  32  and  36  is then passed through a scrubber column  42  that is fed  44  by at least a portion of the de-alcoholised wine  16  to absorb residual aromatics from the vapour  40 . 
     At least a portion of the wine (with absorbed aromatics)  46  exiting the scrubber column  42  is then returned to the de-alcoholised wine  16 . 
     Optionally, at least a portion of the condensed aromatics  38  exiting the first condenser  36  may be subjected to a membrane separation process to remove a portion of the alcohol therefrom. And, at least a portion of the condensed aromatics  38  that has passed through the membrane separation process may be returned to the fermented beverage discharged from the second distillation column  24 . 
     By returning water  28  to the de-aromatized wine in the second distillation column  24  and aromatics  38  and  46  to the de-alcoholised wine  16 , the de-alcoholised wine  16  retains many of its flavour components despite having its alcohol content reduced. 
     The de-alcoholised wine  16  with aromatics  38  and  46  re-introduced is then mixed with wine feedstock  12  (that has not been pre-heated) and stored in a tank  48 , packaged or bottled for ultimate human consumption. For example, mixing 25% de-alcoholised wine  16  having an alcohol concentration of 1% ABV with 75% wine feedstock  12  having an alcohol concentration of 16% ABV yields a wine with an alcohol concentration of 14.5% ABV. 
     The process  10  is a single, continuous process using distillation columns  18  and  24  having no internal moving parts. 
     A second aspect of the invention relates to apparatus used in the process  10  described above. 
     It will be appreciated that, although the process  10  has been described using wine as a feedstock  12 , any other fermented beverage can be used as a feedstock. 
     It will also be appreciated that the flow of wine  12  and  16  during the process  10  can be caused by pumps or gravity employing a double-lock (air-lock type) arrangement to enable draining against the force of the operating vacuum in the distillation columns  18  and  24  and rectifier  26 .