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Cycle Brewing, Pasteurization and You

At Cycle Brewing we started pasteurizing our barrel aged stouts in 2013 after we had our first ever infection issue in a run of Rare DOS flip top growlers, before we even opened our tasting room on Central Ave. We looked around at what we were doing – aging beer in semi-porous wood barrels some we stored outside, and hoping the beer never got infected thanks to alcohol content mostly. We were also hand bottling, that first bad run was 1200 bottles one at a time with a beer gun, it took over 12 hours. We did our best but honestly our best wasn’t ever going to be that effective because we couldn’t use some of the more effective sanitation methods and on top of that beer in wood always has a chance of going bad – and we hadn’t even gotten to adding adjuncts to the beer.

Pasteurization is used in all sorts of beverages, orange juice and milk being the most common but a lot of the beer on the shelf is also pasteurized, macro beer is, even a lot of larger craft breweries went to pasteurization for shelf stability. The process is simple, heat it up to 140°F at least, hold it, cool it down. There are several methods, the most common are HTST and Tunnel.

High Temp Short Time (HTST) or Flash Pasteurization is done to the liquid as it travels from one vessel to another, the big guys do it on the way from the brite tank to the filler, the little guys might do it from tank to tank. This is very effective and gets the beer up to 160+ for a matter of seconds and cools it down. 

Tunnel and Batch Pasteurization are done to the finished package, the beer is in the bottle or can and then heated up to just over 140°F for several minutes.

There are positives and negatives to each side.

The main upside for HTST or Flash Pasteurization is that at 160°F it will kill more stuff quickly because not everything dies at 140°F. It can also be a fairly compact machine.

The downside is that it is done prior to one of the most complicated processes with the most moving parts - packaging. Flash pasteurized beer that is packaged on a dirty machine or with mishandled bottles/cans/caps etc. will still spoil, and bottlers and canners have a lot of narrow channels for the liquid and gases to travel through that are cleaned thoroughly but its very hard to be certain its done 100%.

The main upside of a tunnel or batch pasteurizer is that unless the container is opened it should give you a stable product even if you were only 99.99% effective sanitizing your packaging machine.

The downside is that in theory it is a little harder on the beer because of the extended heating time and a tunnel machine takes up a ton of room comparatively.

We did the only thing we could with what we had at the time, we used our mash tun and sparge heads as a batch pasteurizer, loading the bottles in by hand, heating them up with hot water, and then cooling them down and unloading them. It is hugely labor intensive process and on top of that because of the hazards of heating carbonated beer in a bottle (they explode) we didn’t have a way to measure how hot we were getting the beer itself or for how long so we would just heat them up until they started popping and cool them down, we lost anywhere from 2-10% of each BA beer we released in the last 4+ years – totally worth it for a stable product, until of course it didn’t work.

Spring 2018 was a terrible time for Cycle Brewing, we had been cruising along for 4 years without any issue in bottles, confident that pasteurization was effective (we did before and after lab samples for the first year) and thus we were feeling good throwing hundreds of pounds of coconut, almonds, cocoa nibs etc into the tank, raw because you can’t sanitize a food item without changing its flavor, and relying on pasteurization to give us clean beer. This fell apart as most know, Monday 2018 was a disaster, so was Friday 2018 which never got released, and we had to cancel the best week of the year. Everybody wanted to know what happened, us too, but did it really matter where the infection came from? Both of those beers had hundreds of pounds of adjuncts, were aged in wood, the possibilities were endless and kind of irrelevant because the real question for us is why pasteurization failed so spectacularly. We know we probably introduce beer spoiling bacteria and wild yeast when we open the tank and dump food in but we should be correcting and stabilizing our beer post bottle filling, right?

We had some theories, nothing we could test without a time machine, but felt like we understood what happened to some degree so we bottled up some replacements and sent them off to 3 different labs that would run the only test that would tell us if pasteurizing was still effective – which is unfortunately not the quick and cheap test. The downside of simply running lab tests is that it is only a small sample of the total batch, and it doesn’t always answer the question of whether the beer will spoil or not, just tells you if there is potential. There is yeast and fermentable sugar in most high gravity beers but the beer does not continue to ferment, bacteria and wild yeast may also be present but unable to become active. 

We felt like we were ready to move on from that disaster and then we fired up our new tunnel pasteurizer and tried to run old bottles through to test it. Monday’s and Friday’s and some unreleased Tuesday version 1, they all started exploding, it sounded like popcorn. The eye opening part was that they were exploding when they were getting hit with 132°F water meaning they weren’t even up to 132°F yet, let alone the necessary 140°F to get even 1 Pasteurization Unit (PU). That was a devastating revelation, our method for pasteurizing all releases to date has been heating til they explode and cooling down and it turns out we weren’t really pasteurizing at all because the bottles pop under 130°F. After going through anger and despair over the next day, wondering what to do with tens of thousands of dollars of what seemed like scrap metal to us, it became clear that our current package combination could not be pasteurized using a tunnel pasteurizer.

We looked at other bottle types, champagne bottles hold tremendous pressure, but something wasn’t quite right because we had years of success saying that it had worked. Finally, we looked at the old 22 oz bottles we used for the first 3-4 years, ones we never had a problem with, and after some studying and comparison we decided to give them a try, after all they are 12% heavier meaning thicker glass, so we tried it. Success! Not a single bottle exploded. Of all the things we had done, changing bottles in 2017, just because the ones we had been using were out of stock one time, had changed our process dramatically without us realizing it. Based on tests to date, the old bottles wouldn’t be exploding til the beer reaches 140°F+ meaning our old method was very effective, but the new lighter bottles meant our process was incubating any bacteria and accelerating spoilage which means we were really lucky until we weren’t.

We now have a probe that runs inside of a bottle through the tunnel to give us precise data on what is happening, we can calculate the exact PU’s the beer is pasteurized to, with a pretty high level of certainty because of the speed of the process (the tunnel takes 30 minutes for a bottle to travel from one end to the other) which makes hot or cold spots nearly impossible. We have as much confidence as we can have in our bottled beer going forwards, nothing is going to be 100% effective but this is pretty close. We will be running within industry standards for PU’s to bring the most stable product we can to the consumer starting with RareR DOS.

We take full responsibility for our mistakes, and this was ultimately our fault, looking back there were 1 or 2 little things we might have noticed if we had been worried about it, and the bottle change was our decision. We remain committed to quality and stand behind our product, any issues we will do our best to make right with our customers, fresh releases will always be met with a full refund, older stuff, depending how old we might just offer a replacement beer or if its one of those 500 mL flip tops from 2013, maybe we buy you a beer and hear how on earth you still had one of those things. There is always a chance for a bad bottle, we recognize that and appreciate the folks who come to us first. We never like to hear bad news but we would rather a facebook message or email over a nasty review and no way to get in touch and make amends. 

A quick note about the effect of pasteurization on beer. Hoppy beers are destroyed (in our opinion) immediately, we would never pasteurize an IPA. Malty beers are a different story, and barrel aged beers even more so. Everybody we have talked to that runs pasteurization has had unanimous preference for pasteurized malty beers vs unpasteurized. Pasteurization “ages” the beer and many malty beers could use a little bit of that and our feedback over the years backs this up. We consistently have our customers declare that the bottles are better than the draft, and we agree, and it is almost certainly because the bottles are pasteurized and the draft is not. Why not pasteurize the draft beer? Heating a keg up to exploding sounds absolutely off the charts dangerous and just no, no frickin way. A little age on a big sweet imperial stout, not a lot, but a little can really help the flavors meld together and smooth out the rough edges. We will always maintain that our beers are ready to drink when we sell them and as they are a perishable product, even after pasteurization, shouldn’t be expected to be delicious forever. Many are for a long time, and that is great but we wont guarantee that. We release so many beers each year you might as well enjoy them otherwise you end up needing a storage unit to collect them all. 

Loaded mash tun and sparge head
for batch pasteurization, circa 2014





Tunnel pasteurizer at Cycle Brewing






Old VS New Bottles