An alternative to flash pasteurization and sterile filtration is tunnel pasteurization. Tunnel pasteurization is employed after bottles have been filled and crowned. The bottles are loaded at one end of the pasteurizer and passed under sprays of water as they move along the conveyor. The sprays are so arranged that the bottles are subjected to increasingly hot water until the pasteurization temperature is reached by the beer in the bottles (16). The bottles are then gradually cooled with water until they are discharged from the end of the pasteurizer. Temperature changes have to be made in stages to prevent the bottles from breaking. Bottle breakage is usually no more than 0.1 to 0.2% in the tunnel pasteurizer (12). If greater, it is usually due either to poorly made bottles or the lack of head space.
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