History of Beer Pasteurization
Even Louis Pasteur liked a good beer. His original work that resulted in a process that keeps us all safe from getting sick on bad milk was initially a study on spoilage prevention for beer (and wine). In 1864 he discovered that when beer or wine is heated it killed spoilage causing microorganisms and prolonged the shelf life. He subsequently applied this finding to milk for which he is now famous. As a side note, following his initial beer pasteurization studies he also came up with a design for a controlled atmosphere wort boil process (US Patent # 135245, January 28, 1873). This process improved beer flavor as well as brewery yield. It is pretty safe to say that M. Pasteur was a beer lover just like the rest of us, he wasn’t knocking down glasses of milk on a Friday night.
Essentially what Pasteur invented was the HTST (High Temperature Short Time) Pasteurizer. This design is commonly referred to as Flash Pasteurization. In simple terms, beer is heated to a defined temperature and held for a defined amount of time before quickly cooling. There is also another common method used in the pasteurization of beer called Tunnel Pasteurization.
Nicolas Appert, another Frenchman, developed a process in the early 1800’s to preserve food products by hermetically sealing them in a jar and placing them in boiling water. A Tunnel Pasteurizer operates under this principle. Bottled or canned beer is showered with hot water (not boiling) for a period of time and then cooled. This process is technically called Appertisation after it’s inventor.
Flash vs Tunnel Pasteurization
Both Flash / HTST Pasteurization and Tunnel Pasteurization have widespread usage. Flash Pasteurization exposes the beer to a higher temperature (typically 162° F), but for a shorter period of time (15 - 20 seconds). A Tunnel Pasteurizer operates at 140° F, but usually exposes the beer to that temperature for about 30 minutes. The time/temperature effects on the beer are typically one of the major evaluations points when considering which technology is best for a brewery.
You will find that outside of North America, Flash Pasteurizers have been accepted as the technology of choice. One of the main reasons behind this may be the tendency of European plants to consider energy efficiency/usage as a more important parameter in equipment selection than US facilities.
Technical Details
When considering an equipment purchase of either Flash or Tunnel pasteurization, a brewery commonly evaluates several main factors. These are listed below with some general guidelines:
- Capital Cost of Equipment
Flash Pasteurization has the advantage for equipment cost. The capital cost for a tunnel Pasteurizer that operates at the same rate as a Flash Pasteurizer can cost three times as much. - Equipment Size
Flash Pasteurization is compact. Using the same comparison above, the CBP600 has a 4’ x 6’ footprint with a height of 6’. The tunnel for this same application is approximately 6’ x 20’ x 10’. - Installation Cost
Installation of the skidded Flash Pasteurizer is relatively easy due to size. The process takes approximately two days for a full installation. Conversely, the Tunnel pasteurizer will require much more site work, time, and equipment for the installation. - Utility Cost
Both the Tunnel and the Flash Pasteurizer utilize ‘Regeneration’ principles which essentially recover heat and cooling from the process and reuse it while pasteurizing. The Flash Pasteurizer offers up to 95% Regeneration vs a range of 40% - 50% for a Tunnel Pasteurizer. - Effectiveness
The beer is bottled prior to pasteurization in the Tunnel Pasteurizer so it is essentially bulletproof for effectiveness. Flash Pasteurization technology is also bulletproof but is dependant on the cleanliness of the downstream holding tank and sterility of the filling equipment. A proper sanitation plan is needed to prevent downstream contamination. - The Effect on Beer
The big qualitative question. What did the process do to the beer? Both processes will provide a stable pasteurized product, it is up the Brewery to decide what process is better for their beer.
Other Methods
For beer companies that lack the volume to justify the purchase of either Flash or Tunnel pasteurization equipment, they can choose to utilize the services of a co-packer, which is a third party processing facility. In this business model, the beer is transported to the copacker where it is pasteurized on behalf of the brewery for a processing fee. Challenges of this method include transporting beer to and from the co-packer, as well as meeting the volume requirements of the co-packer in order to secure a contract.
For the largest of breweries, membrane filtration is the other predominant technology used for sterile beer filtration. This process employs a very fine filter to remove microbes. You would typically hear terminology like ‘cold-filtered’ used commercially to describe this sterilization process for beer. Membrane Filtration is an expensive and energy intensive process, which is why it's used in large volume plants processing a lot of beer.
Conclusion
For most craft breweries that have grown to the stage of needing pasteurization, the debate is going to be between Flash Pasteurization (HTST) or Tunnel Pasteurization. Flash Pasteurization offers many benefits over Tunnel Pasteurization, and will be the right choice for most beer companies. Learn more about the Goodnature Craft Beer Pasteurizer.