Bottling for the Future
By: Dave Meheen, President of Meheen Manufacturing Inc.
On the surface bottling may appear straight forward and simple, but in fact it is the single most difficult and complex aspect of brewing. Microbreweries and brewpubs by nature must provide high quality, premium products which can be sold at a premium price just to stay in business. This means the beers we produce and sell must be fresh, properly carbonated and contain the lowest dissolved airs possible. Beyond the beer itself, the cost of packaging and profit are of paramount importance to the breweries success.
Initially you must decide an appropriate bottle size and style. The primary package in the United States has been the 12oz glass bottle in a six-pack carrier. However recently the larger 22oz bottle has gained popularity, especially with small brewers due largely to its cost advantage and profit margin. Eventhough the larger bottle may be attractive from a cost stand point, it may not be the appropriate package for a particular market. Now lets do an estimated cost comparison of the 12oz bottle verses the 22oz bottle by the case. Please note that most distributors will not handle 12oz bottles in six-packs, unless they are in case boxes, and 22oz bottles generally are in a case boxes.
12oz bottle per case
22oz bottle per case
From this price comparison the larger package size has a definite cost advantage over the 12oz package. Not only are the packaging costs considerably less for the 22oz bottle, but the dollar return per ounce of product sold is very attractive. Keep in mind when choosing a package style, this is for your customer and he or she may be on the 6-pack standard, in which case, the larger bottles may not be well received.
Once you have chosen the bottle size, the next step is to choose filling and labeling equipment that suits your needs. When choosing a filler/crowner, a number of things should be considered such as speed, style of the machine, physical size, and cost. The machine you choose must be able to counter pressure fill and have the ability to cap on foam. Shelf life of a beer is dependent on many factors, such as the type of product, how it is stored, the presence/absence of yeast and bacteria and the oxygen content. By far the single most important aspect to a long shelf life is low oxygen content. Capping on foam is the most important and effective means for removing atmosphere and oxygen from bottled beer. A machine capable of capping on foam has the ability to agitate the beer mechanically, knocking CO2 out of solution which scrubs air from the beer as well as displacing atmosphere from the bottle. This reduces air content in the bottle and extends shelf life.
Before choosing the bottling machine, it is important to have a good understanding of the different types of bottling machines available and how they work. Basically for the microbrewer, there are two types of bottling machines available, rotary or monoblock and in line machines. Both styles of machines are available with either long or short tube filling heads. Long or short tube refers to the length of the tube associated with the filling head. Long tube fillers, fill the bottle from the bottom up while short tube fillers run the beer down the sides of the bottle.
Generally speaking the rotary machines available to the microbrewer are short tube fillers with no or single pre evacuation. Remember that the short tube filler runs the beer down the sides of the bottle giving the beer maximum exposure area to the atmosphere in the bottle and maximum air impingement where the liquid meets itself. In an effort to reduce the dissolved air in bottled beer, some short tube fillers offer pre evacuation, which draws some of the atmosphere from the bottle before filling.
Lets take a moment to follow a bottle through a typical rotary filler. The bottle is moved by a conveyor to a lead screw or star wheel that feeds the bottle onto the bottling machine. As the bottle enters the machine it is raised so that the filling head penetrates into the bottle and seals. At this point the machine will pre-evacuate the bottle if it is equipped to do so. The bottle is pressurized from the filler bowl through the center tube of the filling head. After the bottle reaches the same pressure as the bowl on top of the machine, beer flows by gravity out of the bowl and over a spreader that makes the beer run down the sides of the bottle. As the bottle fills with beer, atmosphere inside the bottle passes through the center tube and is returned to the head space of the bowl. In this manner constant counter pressure is maintained against the beer during filling.
The final fill level in the bottle is determined by the length of the center tube in the filling head. Beer will only fill the bottle until it reaches the end of the center tube, because it will flow back into the bowl through the center tube until it reaches its own level. Some machines will purposely over fill the bottles and then suck beer back out of the bottle to the correct fill height. After the bottle is full, it still has counter pressure present that needs to be relieved through what is known as a snift valve. Snift is a term used for releasing the pressure in the bottle in a controlled manner to keep the beer from over foaming. When snifting is complete, the full bottle comes off the filler and is transferred to a conveyor that moves the bottle to the crowning station.
Just before capping you want to thump the product in some way to make it foam to the top of the bottle just as crowning takes place. This can be done in a few different ways; one is to use a CO2 jet aimed into the bottle, another is a jet of warm bleach solution, and the last method is to physically hit the side of the bottle. Ideally the beer foam will just be cresting the top of the bottle as crowning takes place.
Now, lets follow a bottle through a filling cycle on our long tube in line filling machine. Unlike the rotary machine, this machine has no pressure bowl on top. The rotary machine we just talked about is completely mechanical control for all functions and it can be very difficult to make changes to compensate for product conditions. Whereas our small in line filler is computer controlled and the operator can make adjustments for temperature and carbonation. A carbon dioxide source is connected to the machine for counter pressure of the bottles and the machine is connected directly to the clear beer tank. No mechanical pump is used to propel the beer, it is pushed to the bottling machine by the carbon dioxide pressure in the head space of the clear beer tank .
Bottles are indexed under the filling heads and the heads plunge down into the bottle. The filling head forms a seal on the top of the bottle and carbon dioxide is added to the bottle to bring it up to counter pressure. When counter pressure is established in the bottle, the beer valve opens letting beer flow through the long tube into the bottle near the bottom. Filling from the bottom up places the beer in the bottle very gently and has less tendency to foam or impinge oxygen due to agitation compared to the short tube filler. As the bottle fills, the atmosphere above the beer is displaced through an off-gas tube near the top of the bottle and discharged. The off-gas tube also serves to establish fill level in the bottle.
When the bottle is detected full by an electronic sensor, the beer valve is closed and the snift valve opened to slowly relieve the pressure in the bottle. The pressure in the bottle is released until an operator Low Pressure set point is reached. When the Low Pressure set point is reached, the snift valve is closed and a short burst of CO2 is put in the top of the beer. At this same time the filling heads are raised out of the bottle letting residual pressure escape to atmosphere. In this manner consistent, controllable foaming of the beer is produced before the bottle is capped.
The computer on the bottling machine obtains a beer line pressure reading from a pressure transmitter located in the beer manifold before each bottling cycle. The beer line pressure reading is converted to PSI and stored in a memory location in the computer. The computer then uses the beer line pressure to calculate the correct counter pressure in the bottles and stores that value. The computer then monitors the CO2 pressure in the bottles with a second pressure transmitter and when the correct counter pressure is reached, the CO2 valve closes and the beer valve opens. The bottles fill until the electronic fill sensor indicates the bottles are filled. When the bottles are filled the beer valve closes and the pressure in the bottles continues to bleed off through the speed regulating valve. When the pressure in the bottles drops to approximately 9 PSI or less, the snift valve opens and the pressure drops to the LO pressure set point determined by the operator using a knob on the control panel. When the LO pressure set point is reached the speed and snift valves are closed and a burst of CO2 is injected into the bottles. As the CO2 burst peaks in the bottles, the filling heads are raised out of the bottles causing the beer in the bottles to foam displacing unwanted atmosphere from the bottle before capping.
The following is an estimated list of airs pick up for each style of bottling machine. The figures quoted here should only be used in a comparative manner to gain a "feel" of relative efficiency of these various systems.
Type of filler Estimated air pick up
As you can see from these estimates the long tube filler with no pre evacuation is better than the short tube filler with single pre evacuation, but not as good as the short tube filler with double pre evacuation. The relatively high air pick up of the short tube fillers is due to the beer cascading down the sides of the bottle in a thin film which maximizes the contact of liquid with the gas in the bottle. This thin liquid film carries the air at its surface with it as it falls and impinges it into the liquid in the bottom of the bottle, much like a waterfall makes bubbles in the water it lands in. Pre evacuation reduces the air in the bottle by about 70%, which still leaves 30% which comes in contact with the beer. With double pre evacuation the air in the bottle is reduced to approximately 9% of the original.
The long tube filler greatly reduces the liquid surface in contact with the air in the bottle and the liquid is not falling or being agitated. The long tube reaches nearly the bottom of the bottle, so that as soon as filling begins the end of the tube is submerged below the surface of the liquid and air impingement is eliminated.
With all this discussion of airs, what is an acceptable level of dissolved air in beer? There is no established limit, some say any level below 2 mls is OK; however, most brewers are satisfied with 1 ml dissolved air or less in a 12oz bottle.
Now that we have a general understanding of some of the differences in bottling equipment, lets take a few minutes to talk about the beer. Preparation and handling of the beer are very important aspects of bottling. If the carbonation level is wrong or the beer doesn't look right, your customer may abandon you. For the customer, clarity and carbonation are the main issues, unless you are packaging a bottle conditioned product.
Lets assume for a moment that you have a tank of beer that has finished fermenting and is ready to transfer to the clear beer tank. You want the beer to appear clear in the bottle as well as when it's poured. How much filtering if any is needed? Clarification of beer with microbrewers is as diversified as the brewers themselves. Some use DE (Diatomaceous Earth) filters, some use plate & frame filters, some use both and some even use cartridge filters. Microbrewers filter to varying degrees, one will filter to 5 microns for clarity, some will filter all the way to sterile and others don't filter at all. The beer should be good and cold for filtering and carbonating. How much filtering you do before bottling is personal preference. Generally speaking the higher the degree of filtration, the longer the shelf life of the beer.
Beyond the clarity of the beer, carbonation is the most important and in many ways the least understood. To discuss carbonation we must first understand the concept of carbon dioxide gas dissolved in beer. The amount of carbonation in beer is measured in terms of volumes. Most beers are considered normally carbonated with 2.45 to 2.85 volumes of dissolved CO2. Volumes of CO2 is the volume the CO2 would occupy if it were removed from the beer at 1 bar pressure and 0 degrees C, compared to the original volume of the beer. Hence if all the gas in one quart of beer containing 2.5 volumes was removed, it would occupy 2.5 quarts of volume at 1 bar pressure and 0 degrees C.
Carbonation can be introduced into beer in three basic ways, kraeusen, in line or pinpoint carbonation, and in the clear beer tank through a stone. Kraeusen is a method by which actively fermenting beer is mixed with end-fermented beer in a closed tank. As fermentation takes place the beer is carbonated naturally. In line or pinpoint carbonation is done with a sintered stone in a transfer line or hose and the CO2 is injected into the beer stream, carbonating the beer as it passes the stone. Pinpoint carbonation can be difficult to control as it depends on beer temperature, beer delivery pressure, CO2 pressure and flow rates. Most microbrewers choose to carbonate in the clear beer tank using a sintered stone. Carbonating in the tank is the easiest to control, and often the most consistent levels of carbonation can be obtained using this method.
Microbrewers determine carbonation levels in beer by testing or comparing tank conditions to a dissolved CO2 chart. By far the tank and chart method is the most widely used. If you use the tank conditions method, take care to ensure your readings represent the actual equilibrium conditions of the beer. Errors reading the chart can come from inaccurate readings of pressure and temperature. Inexpensive pressure gauges which can have accuracy's of +/- 2 to 7psi is one of the most common causes of incorrect readings. For example, you take a pressure reading from the tank of 10psi and 34 degrees F, go to the chart and read 2.58 volumes, but the gauge is faulty and the tank pressure is actually 12psi. This makes the actual CO2 volume 2.79. Inexpensive gauges are often a few psi off and should not be relied upon for determining volumes of CO2. Errors can also result if the tank conditions are not at equilibrium or from incorrect temperature readings or leakage.
The rate CO2 can be dissolved in beer is directly related to temperature and pressure. Beer at cold temperatures (31-36 degrees F) will accept and hold CO2 in solution much better than beer at serving temperatures. This is very important because the bottling process involves mechanical movement of the beer and changing temperatures which tend to knock CO2 out of solution. Bottling at cold temperatures will minimize CO2 and beer losses.
During the bottling process CO2 will be lost from the beer. Beer should be carbonated 0.10-0.15 volumes higher than the desired carbonation to offset bottling losses. Beer should be bottled cold (31-36 degrees F) to keep foaming to a minimum during filling.
Most microbreweries and pubs find that bottle production rates from 35-70 cases per hour fit their needs. These production rates can be supported with a small bottling machine and 2-3 people. You can expect to pay $25,000 to over $100,000 for new bottling machines of this size. Some used equipment is available at reasonable prices, but watch out, it may cost as much as new equipment in the end. Much of the used equipment is from the soda industry and will require mechanical rebuilding as well as conversion for beer filling. Also used equipment may not support pre-evacuation or capping on foam.
Choosing the right labeling equipment and label style can be as important as choosing the bottling equipment. Remember the label is your bill board and represents your brewery. Label appearance can convey a strong message to the consumer even before he or she tries your beer. The label should be attractive, eye catching and convey the image of the type of product inside.
For the small bottling operation there are basically three types of labels available, pressure sensitive (peal & stick), loose paper and painted. The equipment to apply pressure sensitive labels is generally the simplest and least expensive to buy. Table labelers to apply a pressure sensitive body label will generally cost $3000-5000 and will not keep up with bottling rates above 8-10 bottles per minute. This means if you choose to use a table top labeler you will most likely need to pre label your bottles.
Another option for labeling is a small imported fully automated machine called Enos, which has its own conveyor system and accumulating table. These machines are available for pressure sensitive and loose paper labels and can have options added such as back and neck labels. These machines start at about $10,000 and go up depending on the machine and options. Often these machines can be easily integrated into a small bottling line and eliminate the labor of moving bottles through the labeler by hand.
Painted labels represent a relatively new option for the microbrewering industry. Painted labels are applied using a silk screen machine, which until recently was too expensive for most microbreweries. The silk screen machine made by Miller Process Coatings can paint two colors on the bottle at approximately 10 bottles per minute. The machine costs in the neighborhood of $12,000. The advantage of the silk screen machine is the cost per bottle to label is approximately 1/2 cent per unit. The down side is the added labor and the drying time of the paint.
Each type of label and machine mentioned has its advantages and disadvantages. Generally speaking pressure sensitive labels are the easiest to apply and have good appearance when applied properly. Caution should be exercised when purchasing pressure sensitive labels which are to be applied after filling due to moisture on the bottle. Labels may slip or wrinkle when applied to a moist surface, however these labels are now available with moisture tolerant glues which help. Pressure sensitive labels are also the most expensive at 3.5-10 cents each. Loose paper labels have the advantage of being slightly less expensive than the pressure sensitive and generally can be easily applied to moist bottles. Finally painted labels have a large cost advantage over paper labels at 1/2 cent per unit, but labor to apply the label is higher and drying time is required.
Of course the filling and labeling equipment is only part of the cost of setting up a bottling line. Initial orders of bottles, labels and boxes can be quite costly. Many suppliers will require minimum orders of such things as 6-pack carriers, bottles and labels. For instance, the minimum order for 6-pack carriers might be 100,000 units at $0.32 each. Add to that the cost for minimum orders of all other packaging materials and initial packing costs could easily approach $50,000.
Bottling is challenging in many ways and relatively expensive to start up, but promises great rewards for the brewers willing to meet it head on. As with many aspects of the brewing industry attention to detail and careful planning are the tools needed to bottle successfully. Choose machinery which fits your operation, supports quality filling features, fits packaging your market, and be certain the beer is correct before bottling.