Pasteurization of beer

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. Named after the great French scientist Louis Pasteur, who was able to prolong the drinking quality of beer by holding the beer at 55°C–60°C (131°F–140°F) for a short time, pasteurization is used in the production of most of the draught and bottled/canned beers throughout the world.

Pasteurization is often confused with sterilization. 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. However, low levels of some microorganisms might still survive the heating, albeit without causing spoilage of beer. In sterilization, the heat treatment applied is of such intensity that it kills all microorganisms present.

Methods Of Pasteurisation

For commercial breweries, there are two main types of pasteurisation.

Tunnel Pasteurisation

In tunnel pasteurisation, bottled and canned beers are passed through a long and narrow tunnel while hot water is sprayed over the top of each small pack. There will be several chambers to effectively step up the temperature of the beer before cooling it back down again.

They are moved along on a conveyor belt at a speed to ensure each bottle or can reaches the desired temperature. Typically, tunnel pasteurisation will hold the beer at a peak temperature of 60 ˚C (140 ˚F) for 15-30 minutes. In this process, the package is filled, pasteurised, and then labelled.

Flash Pasteurisation

Flash pasteurisation is also known as high temperature/ short-time (HTST) pasteurisation because that is what the technique is all about. That is higher temperatures that pasteurise in merely seconds. In commercial breweries, this method is normally achieved by a thermal bypass system where the beer flows one way, and hot or cold water flows the other way.

Breweries use two or three-stage plate heat exchangers to facilitate this process. Very thin plates allow for instantaneous exchanges of heat between hot water and cold beer before rapidly cooling the product back down. With flash pasteurisation, the beer is typically held at 72 C (161.6 F) for  20-30 seconds. This will place the beer in the 15-25 PU range. This beer is now ready to be transferred to the package.

Impact on Beer Flavor

Does pasteurizing draft beer impact the taste of the beer? This is a question that has long been debated, and truly a matter of personal taste.

Two things to consider in answering this question:

• When a brew master wanted to demonstrate their prowess at brewing a quality beer, the true measure of the quality of that beer was how good it tasted right from the brewing vessel.

• Do you like to eat your vegetables raw or cooked? Some people might argue that uncooked vegetables have the best taste, and best attributes, such as crispness, and others might argue that cooking the vegetable releases more flavors in the vegetable.

Note

One thing is certain about draft beer, whether it is pasteurized or not, it must be stored at 38° F in order to ensure proper dispensing and taste.