Abstract:
A method and apparatus for monitoring a liquid undergoing anaerobic fermentation in a vessel is disclosed. The apparatus comprises an airlock containing a fluid for sealing the vessel and an electrical circuit operatively arranged to pass a current through the fluid to detect passage of bubbles through the airlock.

Description:
REFERENCE TO COMPUTER PROGRAM LISTING APPENDIX  
         [0001]    This patent includes a computer program listing appendix on compact disc. Two duplicate compact discs are provided herewith. Each compact disc contains a computer program listing as follows:  
           [0002]    Filename: hc11  
           [0003]    Size: 4 kilobytes  
           [0004]    Date Created: Oct. 15, 2002  
           [0005]    Filename: switch28  
           [0006]    Size: 14 kilobytes  
           [0007]    Date Created: Oct. 15, 2002  
           [0008]    The computer program listing appendix is hereby expressly incorporated by reference in the present application.  
         TECHNICAL FIELD  
         [0009]    The present invention relates generally to a method and apparatus useful during anaerobic fermentation, and more particularly to a method and apparatus for measuring the volume and rate of gas produced during anaerobic fermentation, this invention having particular utility during the making of alcoholic beverages.  
         BACKGROUND OF THE INVENTION  
         [0010]    It is common when making alcoholic beverages in the home to place the liquid subject to fermentation into a vessel for anaerobic fermentation, the vessel being closed by a fermentation airlock. The purpose of the fermentation airlock is to prevent undesirable dust and bacteria from contaminating the material being fermented. Therefore it is common to utilize an airtrap, the gas produced by fermentation bubbling though a liquid in the airtrap, the liquid typically containing water and a sterilizing agent such as sodium or potassium metabisulfite. Differing types of fermentation locks are employed, various examples being shown in U.S. Pat. Nos. 4,517,884, 4,842,869, and 5,950,524. A favorite form of airlock is the “S” type airlock, variations being shown in U.S. Pat. Nos. 2,023,153 and 4,717,031, and German patents 412,918 and 957,563. Another prior art form of “S” type airlock is shown in FIG. 1 of this application, this particular form of “S” type airlock being sold under the tradename of TRIPLE RIPPLE.  
           [0011]    The TRIPLE RIPPLE airlock is molded from a clear plastic, all airlocks being quite uniform in size. It has been observed that when using a TRIPLE RIPPLE airlock that each bubble has substantially the same volume, i.e., 1.7 ml. It is also known that during fermentation that equal mole volumes of CO 2  and alcohol are produced.  
         OBJECTS AND SUMMARY OF THE INVENTION  
         [0012]    It is an object of the present invention to monitor bubble events through an “S” type airlock to determine the volume and rate of alcohol production. A bubble event, as used in this application, refers to when a bubble passes through the air lock.  
           [0013]    More particularly, it is a further object of the present invention to utilize the bubble events to set various alarms so that the operator of the anaerobic fermentation apparatus will be provided with certain information to facilitate the making of alcoholic beverages.  
           [0014]    The above objects, and other objects and advantages of this invention will become more apparent to those skilled in the art after a consideration of the following detailed description taken in conjunction with the accompanying drawings in which a preferred form of this invention is illustrated. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]    It should be appreciated that, in the detailed description of the invention which follows, like reference numbers on different drawing views are intended to identify identical structural elements of the invention in the respective views.  
         [0016]    [0016]FIG. 1 illustrates a prior art “S” type airlock sold under the tradename of TRIPLE RIPPLE.  
         [0017]    [0017]FIG. 2 illustrates how a prior art “S” type airlock may be modified to identify bubble events, the airlock being provided with electrodes.  
         [0018]    [0018]FIG. 3 shows a dust cap for the modified “S” type airlock, which dust cap is provided with suitable contacts for contacting the electrodes in the modified “S” type airlock.  
         [0019]    [0019]FIG. 4 shows the modified prior art airlock in combination with an electronic monitoring and alarm device, the airlock being mounted on a vessel suitable for anaerobic fermentation.  
         [0020]    [0020]FIG. 5 shows a bubble interrupting the flow of current through between the electrodes, signaling a bubble event.  
         [0021]    [0021]FIG. 6 shows an embodiment of the electrical circuit of the control means.  
         [0022]    [0022]FIG. 7 shows an alternate embodiment of the electrical circuit of the control means. 
     
    
     DETAILED DESCRIPTION  
       [0023]    With reference initially to FIG. 1, a TRIPLE RIPPLE airlock is illustrated, the TRIPLE RIPPLE airlock being indicated generally at  10 . This airlock consists of a molded clear plastic member indicated generally at  12 , the plastic member including an “S” shaped passageway which will be described later. Extending downwardly from the “S” shaped passageway is a mounting stem  14  which is inserted into the rubber bung or cork  16  of a fermenting vessel  18  so as to be an airtight fit. The airlock is provided with a dust cap  20  at its upper end.  
         [0024]    The “S” shaped passageway includes an upwardly extending portion  22  which is in direct communication with the stem  14 , the portion  22  being essentially cylindrical in cross section. A “U” shaped member  24  having a circular cross section connects the portion  22  with a downwardly extending portion  26  having upper, intermediate, and lower bulbs  26 . 1 ,  26 . 2 , and  26 . 3 , respectively. A further “U” shaped member  28  having a circular cross section connects the lower end of the downwardly extending portion  26  with an upwardly extending portion  30  provided with upper, intermediate and lower bulbs  30 . 1 ,  30 . 2 , and  30 . 3 , respectively. An upwardly extending member  32  is provided with a bulb  34  at its top end, which bulb receives the dust cap  20 . A clear plastic web or flashing  36  extends between the downwardly extending portion  26  and the upwardly extending portion  30 , and also between the downwardly extending portion  26  and the upwardly extending portion  22  to keep the various parts in fixed relationship to each other.  
         [0025]    After the liquid to be fermented is placed in the vessel, which liquid may be a wine must, the vessel is sealed with an airlock at the commencement of anaerobic fermentation. To this end, a sterilizing liquid is placed in the “S” shaped airlock, the sterilizing liquid filling the “U” shaped member  28  and ½ of each of the lower bulbs  26 . 3  and  30 . 3 , the sterilizing liquid being indicated generally at SL in FIG. 2. The sterilizing liquid typically contains either sodium or potassium metabisulfite, although other sterilizing agents may be used. During anaerobic fermentation the yeast is less active than during the initial aerobic fermentation, and the CO 2  produced with escape through the sterilizing liquid one bubble at a time.  
         [0026]    With reference to FIG. 2, it can be seen that the “S” type airlock of the present invention is provided with two electrodes  40 ,  42 . Electrode  40  is embedded in the flashing  36  which extends between the downwardly extending portion  26  and the upwardly extending portion  30 . Additional flashing  44  is provided to one side of the upwardly extending portion  30  for the receipt of electrode  42 . As can be seen from FIG. 2, the electrodes have lower terminal ends that extend into the passageway  28 . Normally the ends of the electrodes are covered with the sterilizing liquid, which conducts electricity. Thus, when a voltage is applied between them, current flows between the electrodes. However, when a bubble passes through the tube  28 , the current flow between the electrodes is interrupted. Dust cap  20 , shown in FIG. 3, prevents dust from settling into the airlock when it is engaged with the top of airlock  12 . Conducting members  21  connect to electrodes  40  and  42 .  
         [0027]    As illustrated in FIG. 4, electrodes  40  and  42  are connected to control means  60  through conducting members  21 . Control means  60  comprises control buttons  65 A,  65 B,  65 C,  65 D, and  65 E, and a display  70 . Bottle  18  contains wine must W. Control means  60  counts the number of times the current between electrodes  40  and  42  is interrupted. Control means  60  determines the status of the fermenting liquid based on the history of bubbles detected. Control means  60  displays the status of the fermenting liquid on display  70 .  
         [0028]    The interruption of the current between the electrodes is illustrated in FIG. 5. Bubble  50 , created by the production of CO 2  during fermentation, envelops the exposed conductive material of both electrodes. Thus, with a low voltage drop across the electrodes, the gas does not conduct electricity between the electrodes. A preferred voltage drop across the electrodes is approximately 5 V, although other voltage drops might be suitable. The control means of the apparatus records each interruption in the current as a bubble event.  
         [0029]    [0029]FIG. 6 is a schematic of an embodiment of the electrical circuit of the control means. The circuit shown comprises electrodes  40  and  42 , a 5 V source, resistor  85 , operational amplifier (op amp)  87 , positive and negative power supplies V +  and V −  to power the op amp, and processor  90 . Processor  90  is a conventional microprocessor, well known to those in the electronics art. The 5 V source is connected across electrodes  40  and  42  through resistor  85 . When current exists between the electrodes, V in−  is 0 V. (The 5 V source is shorted to ground.) However, when a bubble interrupts the current through the electrodes, V in−  is no longer zero. (Ground is separated from V in−  by an open circuit.) V in+  is connected to ground. Thus processor  90  can determine the presence of a bubble between electrodes  40  and  42  from the output of operational amplifier  87 .  
         [0030]    [0030]FIG. 7 shows a second possible embodiment of control means  60 . This embodiment comprises a plurality of control buttons  65 A,  65 B,  65 C,  65 D,  65 E, and  65 F, electrodes  40  and  42 , a 5 V source, resistor  89 , pin  88  of processor  90 , audio alarm  92 , and visual alarm  94 . Pin  88  of processor  90  is connected to electrode  40  and to a 5 V source through resistor  89 . Electrode  42  is connected to ground. When current exists between the electrodes, pin  88  is shorted to ground. When the current is interrupted by a bubble, pin  88  will be lifted to a non-zero voltage. (The voltage level will depend on the resistance value of resistor  89 ). In this manner, processor  90  can determine the presence of bubbles between electrodes  40  and  42 .  
         [0031]    To use the above-described device, a measure volume of a liquid subject to fermentation, such as a wine-must, is placed in a container. (This is typically done after a period of aerobic fermentation and a hydrometer measurement to determine the proportion of sugar remaining.) The airlock of the present invention is inserted in the neck of the container. The user programs the volume of liquid present in the container using the control buttons.  
         [0032]    In a preferred embodiment, control means  60  are configured as follows. First, the batch size must be set. Button  65 A increases the batch size by 10 liters each time it is pushed. Button  65 B increases the batch size one liter each time it is pushed. Button  65 C accepts the batch size when it is pushed, if the batch size is non-zero. (Buttons  65 D and  65 E have no function in setup mode). After the batch size is set, the user can enter a user specified time alarm, to be activated when the enter amount of time passes without a bubble being detected. Button  65 A increases this alarm time by one hour each time it is pushed. Button  65 B increases this alarm time by one minute each time it is pushed. Button  65 C accepts the current alarm time. (Zero may be entered if no user specified time alarm is desired.) When the user specified alarm is set, the user can then enter an alcohol alarm level. Button  65 A increases the alcohol level alarm by one percent each time it is pushed. Button  65 B increases the alcohol level alarm by one tenth of one percent each time it is pushed. Button  65 C accepts the current alcohol level. After the alcohol level alarm is set, the user can activate the 24 hour alarm. Button  65 A enables the 24 hour alarm. Button B disables the 24 hour alarm. Button  65 C accepts the current 24 hour alarm status. The control means then detects the bubbles of gas escaping from the airlock and displays the status of the liquid on display  70 .  
         [0033]    The status is determined based on the history of bubbles detected by control means  60 . In one embodiment, airlock  12  is configured such that the escaping bubbles have a volume at room temperature and 1 atmosphere of pressure of 1.7 ml. (It is assumed that the fermentation is done at a constant temperature, thus an equal amount of gas is contained in each bubble). Thus, by counting the number of bubbles, control means  60  can determine the amount of gas to escape from the airlock. According to calculations known in the art, the amount of alcohol generated during anaerobic fermentation can be determined based on the volume of CO 2  generated (assuming substantially all of the escaping gas is CO 2  generated by fermentation) and the amount of liquid present in the container (input using the control buttons, as discussed above). Accordingly, control means  60  can calculate the volume of alcohol generated and display this amount on display  70 .  
         [0034]    In a preferred embodiment the buttons of the control means function as follows. Button  65 A scrolls the display of the bubble events towards the most current event. Button  65 B scrolls the display of the bubble events towards the least recent event. Button  65 C deletes the display of the displayed event if pressed alone. Button  65 D caused the control means to reenter setup mode. Button  65 E silences current alarms and calls up a screen to review past alarms. Display  70  is set to the most recent event when button  65 E is released. When buttons  65 C and  65 E are pressed simultaneously, past alarms are cleared.  
         [0035]    As discussed above, a user can preprogram a percentage of alcohol desired with the control buttons. In this case, control means  60  displays a countdown of the amount of alcohol still to be generated. Control means  60  can include an audible alarm  94  and/or visual alarm  96  to signal a user when the desired amount of alcohol has been produced. This can be especially useful in making beverages wherein some fermentation is desired after the liquid is bottled. The alarm can be set to alert the user when a portion of the desired alcohol has been produced. The user can then transfer the beverage to individual bottles for the remaining fermentation. This is also useful for the production of a sweet beverage. The user can stop fermentation before all the sugar has been consumed by the yeast.  
         [0036]    Control means  60  also includes timing means to determine the amount of time between each bubble. Counting means displays the amount of time since the last bubble on display  70 . Audible and/or visible alarms can be activated to alert the user after a specified time without a bubble has been reached. In one embodiment, this time period is 24 hours. In another embodiment, this time period is set by the user using the control buttons (the user specified alarm discussed above).  
         [0037]    A potential problem with fermentations that can take a long period of time is the evaporation of the sterilizing liquid. If the sterilizing liquid evaporated to the point wherein outside air may pass into vessel  18 , then the fermentation may be spoiled. The present invention warns a user when the level of the sterilizing liquid is low. Electrodes  40  and  42  are placed in member  28  such that they are exposed to air before the liquid level drops to an extent that air could reenter vessel  18 , as shown in FIG. 2. Control means  60  times the length of the bubbles. If the sterilizing liquid has partially evaporated, then the electrodes will be exposed to air continuously. Thus, when control means  60  detects an interruption of the current that lasts an extended period of time (in one embodiment 1 hour), it displays a low liquid level warning on display  60 . Audible and/or visible alarms may also be activated. In addition, bubble detection indicator  92  is lit when a bubble is being detected (when current is not flowing between electrodes  40  and  42 .) This can also allow a user to determine there is a problem if the bubble detection indicator remains lit for an extended period of time. The low liquid level warning and bubble detection indicator allow a user to replace the lost sterilizing liquid before the fermenting liquid is spoiled.  
         [0038]    [0038]FIGS. 2, 4, and  5  show the present invention being practiced with an “S” type airlock. However, it should be readily apparent to one skilled in the art that other airlocks or valves may be modified to practice the present invention. FIGS.  8 - 10  illustrate several valves known in the art. FIG. 8 shows a flapper check valve  110 . Electrodes  140  and  142  contact conducting strip  145  on flapper  115  when the valve is closed. Thus, when the valve is closed, current flows from electrode  140  to electrode  142  through strip  145 . When flapper  115  is forced open by gas pressure, the current flowing between electrode  140  and electrode  142  is interrupted. Thus, the number of times gas escapes from the valve can be counted. The amount of gas that escapes each time is measured and programmed into control means  60 . In this manner, a fermentation process can be monitored as described above. In a similar manner, FIG. 9 shows a piston check valve  210  comprising electrodes  240  and  242 , and valve member  215  having conducting strip  245  on a surface thereon. When the valve is closed, current flows from electrode  240  to electrode  242  through strip  245 . When member  215  is forced open by gas pressure, the current flowing between electrode  240  and electrode  242  is interrupted. FIG. 10 shows ball check valve  310  comprising electrodes  340  and  342  and conducting ball  345 . When the valve is closed, current flows from electrode  340  to electrode  342  through conducting ball  345 . When ball  345  is forced up by gas pressure, the current flowing between electrode  340  and electrode  342  is interrupted. The amount of gas released each time the valve opens is used to determine how much gas is produced during fermentation, in the manner described above. These modifications, including the use of the practicing of the present invention with other valves not shown, is intended to be within the spirit and scope of the invention as claimed. In the present specification and claims, the word “airlock” is intended to mean any airlock or valve known in the art or hereafter developed that can be modified as described herein to practice the present invention.  
         [0039]    While a preferred form of this invention has been described above and shown in the accompanying drawings, it should be understood that applicant does not intend to be limited to the particular details described above and illustrated in the accompanying drawings, but intends to be limited only to the scope of the invention as defined by the following claims. In this regard, the term “means for” as used in the claims is intended to include not only the designs illustrated in the drawings of this application and the equivalent designs discussed in the text, but it is also intended to cover other equivalents now known to those skilled in the art, or those equivalents which may become known to those skilled in the art in the future.