Anaerobic fermentation method and apparatus

REFERENCE TO COMPUTER PROGRAM LISTING APPENDIX

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:

Filename: hc11

Size: 4 kilobytes

Date Created: Oct. 15, 2002

Filename: switch28

Size: 14 kilobytes

Date Created: Oct. 15, 2002

The computer program listing appendix is hereby expressly incorporated by reference in the present application.

TECHNICAL FIELD

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

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.

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

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.

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.

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

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.

FIG. 1

illustrates a prior art “S” type airlock sold under the tradename of TRIPLE RIPPLE.

FIG. 2

illustrates how a prior art “S” type airlock may be modified to identify bubble events, the airlock being provided with electrodes.

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.

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.

FIG. 5

shows a bubble interrupting the flow of current through between the electrodes, signaling a bubble event.

FIG. 6

shows an embodiment of the electrical circuit of the control means.

FIG. 7

shows an alternate embodiment of the electrical circuit of the control means.

FIGS. 8 through 10

show valves known in the art.

DETAILED DESCRIPTION

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.

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.

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 will escape through the sterilizing liquid one bubble at a time.

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

.

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

.

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.

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

.

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

.

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.

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

.

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

.

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.

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.

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).

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.

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.

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.