Process info: Pasteurization in beer production
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PASTEURIZATION IN BREWERIES
1. DESCRIPTION OF TECHNIQUES, METHODS AND EQUIPMENT
- Description of the pasteurization of beer
- (“Energy Efficiency Improvement and Cost Saving Opportunities for Breweries”, University of California, Sept. 2003)
One of the final stages in beer production is the pasteurization of beer, which follows the fermentation step. The beer must be cleaned of all remaining harmful bacteria before bottling. One method to achieve this, especially for beer that is expected to have a long shelf life, is pasteurization, where the beer is heated approximately to 60°C to destroy all biological contaminants. Different pasteurization techniques are tunnel or flash pasteurization. Energy requirements for pasteurization can vary from 19-23 kWh per 1000 bottles for tunnel pasteurization systems (Hackensellner, 2000). Other estimates are 14-20 kBtu/barrel (Anheuser Busch, 2001). An alternative approach is the use of sterile filtration (Bamforth, 2001). However, this technology is new, and some believe these systems may require as much extra energy as they save (Todd, 2001).
2. NEW TECHNOLOGIES
- a) Changes in the process
- Membrane processes in beer pasteurization
(http://www.alfalaval.com/ecoreJava/WebObjects/ecoreJava.woa/wa/showNode?siteNodeID=3301&contentID=31152&languageID=1) (see also Membrane processes in the food industry).
a.) Description of the technology: Cold pasteurization is a membrane-based filtration method for pasteurizing beer with no heat impact. The method makes it possible to produce a final product that is a beer of a particularly high quality. The advantage of these filters lies in a special membrane that is ideal for meeting the filtration requirements associated with beer production, and guarantees the removal of all microorganisms that could spoil the individual batch. In addition, low adsorption of unwanted particles, colloids and proteins in beer reduces the load placed on the final membrane. This makes it easier to clean and reuse the membrane. Chemical regeneration, using the standard cleaning procedures for breweries, makes it possible to use the membrane for a long operation time. In addition, the membrane material withstands the highest levels of mechanical and thermal stress. The standard design includes in situ integrity testing of the membranes in order to guarantee that the beer is free of beer-spoiling microorganisms.
b.) Description of suitable energy supply systems: Membrane processes may result in reduced heat consumption, but electrical power is required to pump liquid through a semi-permeable membrane.
c.) Possible energy savings reachable by those measures
d.) Economic evaluations
- Flash (plate) pasteurization in beer production (“Energy Efficiency Improvement and Cost Saving Opportunities for Breweries”, University of California, Sept. 2003)
a) Description of the technology: Flash pasteurization is used for in-line heat treatment of beer prior to filling the kegs and small-packs for the purposes of microbiological stability. According to Goldammer (2000), flash pasteurization is not widely used by breweries in North America, though it is very popular with the dairy and juice industries. Flash pasteurization has been widely adopted by brewers in Europe and Asia. Flash pasteurization rapidly heats the liquid for a short period of time to a high temperature and then rapidly cools the product. As opposed to conventional tunnel pasteurization, flash pasteurization requires less space, steam, electricity and coolant.
b) Description of suitable energy supply systems: In this case, a typical pasteurization energy supply system is needed. A boiler may be used to produce steam for the process and electricity is required for pumping steam and coolant into the system.
c) Possible energy savings reachable by those measures: The optimum heat recovery is 94-96%, but plate systems tend to require trim chilling of the beer before packaging (Kidger, 2001). Energy consumption is estimated at roughly 3-7 kBtu/barrel, estimated to be 1/3 of the energy used in tunnel pasteurization (Hackensellner, 2000; Singleton, 2000; Dymond, 1997). Because of the relative compactness of flash pasteurization systems as compared to tunnel systems, initial investment costs are lower, and run roughly $30/barrel ($26/hl), or about 15% those of tunnel systems (Battaglia, 2001; Hyde, 2000). Operation and maintenance cost estimates for flash pasteurization systems were estimated to be $0.25/barrel ($0.2/hl), compared to $1.7/barrel ($1.4/hl) for tunnel pasteurizers (Dymond, 1997). Since flash pasteurization is integrally linked to the purchase and use of sterile filling technology, the use of flash pasteurization may include significant additional costs associated with sterile filtration requirements.
d) Economic evaluations: Because of the relative compactness of flash pasteurization systems as compared to tunnel systems, initial investment costs are lower, and run roughly $30/barrel ($26/hl), or about 15% those of tunnel systems (Battaglia, 2001; Hyde, 2000). Operation and maintenance cost estimates for flash pasteurization systems were estimated to be $0.25/barrel ($0.2/hl), compared to $1.7/barrel ($1.4/hl) for tunnel pasteurizers (Dymond, 1997). Since flash pasteurization is integrally linked to the purchase and use of sterile filling technology, the use of flash pasteurization may include significant additional costs associated with sterile filtration requirements.
- b) Changes in the energy distribution system
- Heat recovery in beer pasteurization: (“Energy Efficiency Improvement and Cost Saving Opportunities for Breweries”, University of California, Sept. 2003)
a) Description of the technology: While all modern pasteurizers use some form of internal heat regeneration, the heat contained in the rejected water can be recovered using heat pumps or heat exchangers (Sorrell, 2000). The operation of the heat pumps can be matched to the heating and cooling requirements of the bottle washer.
b) Description of suitable energy supply systems: A circuit of heat exchangers and tanks is needed to achieve the heat transfer. Electrical energy will be consumed to operate the pumps of the circuit.
c) Possible energy savings reachable by those measures: A brewery in Canada was able to recover 0.6 kBtu/barrel from its pasteurization process (Singleton, 2000).
d) Economic evaluations##
- c) Changes in the heat supply system
