I know from living overseas that the only beer they pasteurize is labeled "EXPORT".
It is meant to last over 90 days. This is ensure its drinkability after delivery to the store where you buy it.
Everyday drinking beer is not pasteurized.
From brewingtechniques.com:
PASTEURIZATION AND MICROBIOLOGICAL STABILITY
Q: I am in the process of writing my business plan for my new microbrewery. I am going to launch my beer as a contract brew. The contract brewer that I'll be using pasteurizes its beer, as do most regional brewers. Could you explain the differences between flash and tunnel pasteurization? Also, what if any effect does pasteurization have on the flavor of the beer? Most micros use ultrafiltration instead of pasteurization, "because nonpasteurized beer tastes better." Is this really true? Or are most micros using filtration because of the cost?
DM: Any type of pasteurization is a process of heating beer to kill off or stun yeast or bacteria that may be living in the bright, filtered beer. If done correctly, it renders the beer microbiologically stable, which means it will not spoil even if stored for several months at room temperature. This is important for bottled beer. The alternative to pasteurization is sterile filtration, which means running the beer through a filter so tight that it traps all microbes that were in the beer. This also results in a microbiologically stable product.
Tunnel pasteurization involves passing bottles or cans of beer through a pasteurizing tunnel on a conveyor belt. Inside the tunnel, the bottles are sprayed with hot water until the contents are heated to 140 °F (60 °C) and then held at that temperature for 10 min. Then the bottles are sprayed with cold water to cool them down.
Flash pasteurization involves basically passing beer through two heat exchangers. The first one operates in the reverse manner from a counterflow wort chiller - instead of cold water, hot water is pumped in a flow that runs counter to the cold beer, heating it very rapidly to about 160 °F (71 °C). It is held at that temperature for only about 20 seconds before going into the second heat exchanger, which cools it back down.
All three methods have advantages and disadvantages. All of them can and do damage the flavor of the beer. The question is "How much?" and "In what way?"
Sterile filtration strips body, flavor, and even color from beer. A filter tight enough to trap all bacteria also traps large molecules such as proteins, dextrins, and melanoidins. These substances are responsible for the mouthfeel, head retention, color, and in part the flavor of beer. Thus, sterile filtration is fundamentally more compatible with light-bodied pale beers (such as the products of the major American breweries), than it is with the darker, fuller bodied craft-brewed beers.
I have heard a microbrewery owner call stripping "a home brewer's term." Let me assure you the Big Guys are quite familiar with the word - and the phenomenon. In fact, one of the major brewers filters its "bottled draft" products using only 0.65-µm rated filters rather than the 0.22-µm filters required for 100% effectiveness. They do this to minimize the damage caused by stripping. In effect, they have chosen to accept the risk of a few rod-shaped bacteria slipping through the filter in exchange for more body and flavor in the finished beer.
Pasteurization damages beer by greatly accelerating oxidation. Obviously, the degree of damage depends on both the time and temperature of the pasteurization cycle and on the oxidation potential of the beer itself. Beer oxidizes in the bottle because of oxygen dissolved in the finished beer (mostly during filling) and because of oxidized tannins and melanoidins that are created by hot-side wort aeration. Clearly, the lower the dissolved oxygen in the bottle ("package air" in trade lingo) and the better the hot wort was handled, the less pasteurization will damage it. Nonetheless, pasteurization always does some damage, though it is not always immediately noticeable.
Flash pasteurization is less damaging, in terms of oxidation, than an equivalent degree of tunnel pasteurization. Though the temperature is higher, the time is far shorter. Also, flash pasteurization takes place before the beer is bottled, so the dissolved oxygen level is much lower when the beer is heated. Flash pasteurization, however, shares with sterile filtration the serious drawback that it requires aseptic filling. Aseptic filling means filling the package under sterile conditions. The beer may be stable when it leaves the flash pasteurizer or sterile filter, but if the filler or capper is contaminated it will not be stable in the bottle.
An aseptic filling line and the room that houses it must be kept as clean and sanitary as a hospital operating room and its equipment. If you have ever taken a close look at a bottle filling machine, you will appreciate what a challenge this is. Older breweries with older equipment, which were not built with the requirements of aseptic filling in mind, often have a lot of trouble trying to produce "cold-filtered draft" (sterile-filtered, aseptically filled) bottled beers.
If I were trying to do what you are doing I would accept the method of stabilization recommended by the brewmaster. He or she knows best what the plant's capabilities are. But I would also try to do a real-world assessment of the beers produced there. I assume they are turning out microbiologically stable beers. Because they use pasteurization, you need to try to assess the oxidative stability of the products. Try to get hold of some of their bottled beer of various ages - one month, two months, three months - and compare them with freshly bottled and fresh draft examples of the same brands. That should give you some idea of how much damage pasteurization will do to your beer.
In my opinion, most micros opt for sterile filtration because of the lower initial cost. Note, however, that filter cartridges are expensive, and replacement represents a large ongoing expense. Pasteurization can actually be cheaper over the long run.
It sounds like you hope to eventually build your own brewery. If or when you reach that stage, then you should seriously look at all three options in terms of both initial and long-term cost. I would also recommend that you talk to brewers working with all three methods to get an idea of their ease of operation and maintenance requirements. Also, do some critical taste evaluations of products that are similar to the one you want to make and that have been treated by each method. Any of these methods can give you good stable beer, but none of them is flawless or foolproof.
