pasteurize to kill potential infection?

[Ladd]

Hey all,

I had a great tasting pumpkin ale that I bottled up two weeks ago. Popped the top on one yesterday to find 350ml of malt vinegar... I am assuming the bug is acetobacter as the pumpkin ale was around 7.5% ABV and it tastes just like vinegar. there was no sign of infection at bottling time either. Now my concern is that at the same time I bottled my pumpkin ale, I was also making a RIS. I am now super paranoid that my RIS is also infected. I took a sample last night and it is at it's FG (stable for three days) and tastes great. To satisfy my paranoia, I am thinking of putting it in my kettle and bringing it gently up to 160 for a short time to kill off anything that may potentially be in there. I could then to cool it, pitch some new yeast for carbing and bottle it right away.

I have never had to do this before and was wondering if anyone can give me their opinion on this? Will doing this ruin the flavor of the beer since there is still likely a lot of yeast in suspension that will be killed off? It's about 8.5% ABV and I am concerned that if I just leave it, by the time it carbs up it will be ruined.

Not sure how it happened, I am super neurotic with my cleaning and sanitizing regiment... Obviously I overlooked something somewhere...

Thanks for you thoughts!

[mr x]

Don't know what to tell you there. Tough call...

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[Ladd]

I am concerned with all the yeast death, that there will be serious off flavors if I pasteurize it right now. I think I'll move this fermenter into my refrigerator/fermchamber and drop it down to around 4°C for the next few days to try to crash all the yeast out. This should also slow or stop the growth of any potential infection. Then I think I'll pasteurize it, repitch some yeast with my carbonation sugar and bottle. Anyone else have any other ideas? Love to hear them!

Thanks!

[mr x]

Sounds like a reasonable approach.

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[GuingesRock]

Is there any way you can draw off a sample. Then subject one half of the sample to the pasteurisation process cool and compare the two halves, check for gravity (to assess loss of alcohol from heating) and taste to determine if any taste detriment caused by the pasteurisation with yeast present. Bread doesn't suffer from being baked at high temps

[Ladd]

Is there any way you can draw off a sample. Then subject one half of the sample to the pasteurisation process cool and compare the two halves, check for gravity (to assess loss of alcohol from heating) and taste to determine if any taste detriment caused by the pasteurisation with yeast present. Bread doesn't suffer from being baked at high temps

That's a good idea, thanks! I'll give that a go before doing the whole batch just to see. I wish I was set up for kegs. I'd just keg it, force carb it and keep it cold until it was gone.

[GuingesRock]

You never know, the results might be really good, and pasteurizing followed by bottle conditioning might become a new process...the "Matt Process", or "Ladd's procedure"

[RubberToe]

How many bottles of the pumpkin ale have you opened? Maybe the infection is limited to one or a few bottles.

[Ladd]

You never know, the results might be superb, and pasteurizing followed by bottle conditioning might become a new process...the "Matt Process", or "Ladd's procedure"

hahaha somehow I doubt that it will become a new fad, additional brewing steps and all... but that is the wonderful thing about experimentation! You just never know! I'll keep notes on this one and post back when I pasteurize it and then again when I start drinking it to let you all know how it turns out.

I'm also going to bottle a couple up before pasteurizing it, just to see in a few weeks if it was infected (I need to know!). I hope not just for the peace of mind aspect for my next brewing session!

[Ladd]

How many bottles of the pumpkin ale have you opened? Maybe the infection is limited to one or a few bottles.

I only opened two so far, but they were identically terrible... I was too upset to keep going I'll pop a few from each case just to make sure.

[Ladd]

It's definitely all of them

[GuingesRock]

I'm also going to bottle a couple up before pasteurizing it, just to see in a few weeks if it was infected (I need to know!). I hope not just for the peace of mind aspect for my next brewing session!

Simply bottling half and pasteurising the other half before bottling might work with least fuss. Kind of hedging your bets. You would end up with two batches of beer to compare. Both could be good, both could be bad, one might be bad. The results would be interesting, whatever the outcome.

You got me thinking about beer vinegar. Does anyone make that for culinary use?

[CartoonCod]

...

and it tastes just like vinegar.

My memory might be playing tricks on me again, but I thought you needed a combination of oxygen and acetobacter to get vinegar out of alcohol. If so, you would still want to consider doing something for the infection, but also look at potential sites where oxygen could be getting into your system. If you heat up beer to pasterize it when it contains oxygen you will get an increased rate of oxidation.

[Ladd]

You are right, from what I have read about it (I have been doing lots of that lately...) it does require oxygen and other than oxygenating my wort when pitching yeast the only time it moves after that is right into my bottles, I don't bother to secondary unless I am adding fruit, and I just bottle right from the primary. I fill the bottles to about 1 finger space from the cap and I am pretty sure I don't introduce much if any oxygen then. I set my caps on but don't stamp them right away and let the beer off gas a little to help displace any oxygen that was left in the bottle. I have never tasted 'cardboard' type flavors in my beers either.

It may not even be acetobacter, I might be misinterpreting the sour taste. I have also read that if is acetobacter, there should be a really sharp acetic acid in the aroma and I don't have that. A freshly opened bottle just smells faintly of the spices I put in. It sure is sour though... Maybe its lactobacillus? I read it has a low alcohol tolerance though and wouldn't be quite as fast acting. This went form yum to yuck in two weeks.

I am going to take Marks idea and do a test run and only pasteurize a glass full to see if there is any impact on the flavor. Its still in my ferm chamber at 4°C right now. I may even just bottle up a half a dozen and test one a week until they are carbed and see how they are tasting, leaving the bulk in the fermentor cold. This would tell me if I even have an infection in this one. It is likely fine and I am just being paranoid about it.

[Ladd]

I thought I would throw an update in on this if anyone is interested. So I ended up bottling 4 bottles of the RIS and have opened one each week to see if there were any problems. The rest of the batch was kept in the fermenter at 4°C just in case. I opened the fourth one the other night and while it was still not fully carbonated it was infection free and starting to taste pretty damn good! I am happy to report that the infection was limited to the pumpkin ale only! I went ahead and bottled up the rest of the batch this evening.

I was curious about the effect of the pasteurization process though so at the same time I had heated an additional liter of it in a pot on the stove and brought the temp up to 70°C and held it there for 10 minutes. I then cooled it, pitched a little fresh yeast with my conditioning sugar and bottled it. I did a side by side with the last bottle I opened and it was really, really terrible... Very dank and pungent tasting... Almost tasted a bit like a yeast cake smells if you can imagine that. Very hard to describe but not by any means pleasant.

I am so glad I didn't do that to the whole batch, it would have been a dumper for sure!

Hope that may help anyone faced with the same situation I was.

[adams81]

I am facing this issue right now and was reading this thread yesterday. Thanks for the update!

[NASH]

I expect heating to those temps at atmospheric pressure drives off a lot of the alcohol (!) so you're better off anyways