![]() Instead, beer is heat treated by being passed through a heat exchanger (hot water gives up its heat by exchanging with cold beer over a large surface area) where the beer will be heated to 70☌–72☌ (158☏–162☏) for as little as 30 sec. The spraying chamber is called a “tunnel” and the process is therefore called “tunnel pasteurization.” For large containers of beer such as kegs, heating the contents of the keg in a tunnel is impractical. Bottled and canned beers are pasteurized by passing the filled containers through a long, relatively narrow chamber in which hot water is sprayed over the containers for a fixed time before cooling. There are two major methods of beer pasteurization. Holding for 15 min at 60☌, therefore, is 15 PUs of treatment. For every minute the beer is held at 60☌ it is said to be subject to one pasteurization unit (PU). ![]() The brewing industry uses this temperature of 60☌ as a basis for quantifying the extent of the pasteurization process. ![]() Initially, based on a largely empirical observation, holding beer at a temperature of 60☌ (140☏) for a few minutes was deemed sufficient to maintain microbiological integrity over its shelf-life of several months. In sterilization, the heat treatment applied is of such intensity that it kills all microorganisms present. However, low levels of some microorganisms might still survive the heating, albeit without causing spoilage of beer. In the former, the beer is subject to sufficient heat processing to render the beer free from microbial spoilage during the course of its shelf-life. Pasteurization is often confused with sterilization. Named after the great French scientist Louis Pasteur, who was able to prolong the drinking quality of beer by holding the beer at 55☌–60☌ (131☏–140☏) for a short time, pasteurization is used in the production of most of the draught and bottled/canned beers throughout the world. Hot fill compatible PET bottles are more expensive.Pasteurization is the process of heat treating beer to inhibit the growth of potential beer spoilage microorganisms and prolong the shelf life of the beer.It cannot be used for carbonated products due to the excessive amount of foam created when introducing CO 2 to a hot product.Allows beverages to potentially be labeled as “natural,” depending on other factors.More cost-effective than Tunnel Pasteurization.After being held at this temperature for about 15 - 30 seconds, reducing microorganisms and preventing bacterial development, the liquid is subsequently cooled down to approximately 180 - 185☏ (82 - 85☌) before it gets filled into the packaging. In the hot filling process, the beverage is first pasteurized and heated to a high temperature typically ranging between 190 - 203☏ (or 90 - 95☌). Hot Filling is often found in facilities filling PET bottles, but can also be used in glass bottles and cans. The liquid is then filled at a high enough temperature to sterilize the interior contents of the primary packaging. The liquid is injected into a large vat where it is heated to a high temperature and held for a short amount of time. Similar to Tunnel Pasteurization, Hot Filling uses heat to pasteurize the product. Can negatively affect flavor and cause product inconsistencies.Can occasionally require additional equipment leading to additional expenses.Limitations on the amount of CO 2 that can be added to the product.Commonly used, increasing contract packer options for brands.Beverages can potentially be labeled as “natural.” Additional requirements must be met.Here is a commonly used PU formula: PU = t × 1.393 ((T − 60)/T) where T = degrees in Celsius, t = the time in minutes at which the product is held at T. One PU defined as the micro death that occurs when the beverage is held at 60☌ (140☏) for one minute. ![]() Timing and temperature is calculated based on the number of required pasteurization units (PU). ![]() Both are held for a predetermined amount of time to ensure microorganisms (micros) are killed. Tunnel pasteurization uses multiple stages of heating a beverage and its packaging to target temperatures. It can be used for PET bottles, but it can be costly and ineffective at prolonging shelf life. Tunnel pasteurization is commonly used in aluminum can and glass bottle filling. Get in Touch With a Beverage Specialist Now In our three-part series, we define each method and discuss the primary advantages and disadvantages of each.
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