Concerned about yeast starter

[Rasher]

Hi,

I made a starter 4 days ago using White Labs WLP590 French Saison Ale Yeast, let it do its thing for just over 24 hours and then put it in the fridge for about 3 days to let it cold crash.

The first thing I thought was strange is that the yeast wasn't really flocculating out like I had hoped it would (wasn't going clear on top). Then I decided to try some today to make sure it wasn't infected or anything, and the smell and taste is kind of sour and like vinegar. I wasn't expecting the taste to be pleasant but I didn't really expect it to be like that. There's some white bubbles up the top of the starter vessel too, which I found slightly concerning but I don't know if it looks like an infection. I've included some pictures so you see what I mean.

This is my first time making a starter and just used a sanitised plastic bottle with some sanitised tinfoil over the top because I was doing it on the cheap. I was planning on brewing tomorrow but I'm thinking of holding off now and perhaps dumping this starter if it's infected. Any help would be greatly appreciated.

Thanks

 

[Rochefort]

Tricky to see exactly what those bubbles are, but if it looks like it might be mold growing then I would chuck it. Maybe a step was missed when the starter was made.

Everything has to be sanitised, including the funnel, the outside of the yeast packet and any scissors, and the wort needs boiling for 15 minutes before rapidly cooling down to 20 C.

 

[Rasher]

Tricky to see exactly what those bubbles are, but if it looks like it might be mold growing then I would chuck it. Maybe a step was missed when the starter was made.

Everything has to be sanitised, including the funnel, the outside of the yeast packet and any scissors, and the wort needs boiling for 15 minutes before rapidly cooling down to 20 C.

Thanks for your reply. I sanitised absolutely everything including the scissors, yeast packet and funnel. I had it all sitting in some star san solution for at least 15 minutes. I don't think the bubbles look like mold growing, I just found them a bit peculiar, and wasn't expecting them there. I'm tempted to chuck it just in case, and start again but I have no idea what I did wrong.

 

[Rochefort]

Liquid to liquid transfers are always the most risky, especially if the actions include pouring rather than using a pipette. It is easy to miss a step or introduce something airbourne during each transfer. In the labs I worked in we used to do solid to liquid transfers on the lab bench, but all liquid to liquid transfers were done in a microbiological cabinet that had been sterilized by UV and had microbe-free air. And we never poured anything, it was just too risky.

Your process would have involved three of these 'pouring' transfers. You can remove one of those transfers by making your starter culture in your FV and racking the wort on top on brewday. Or, invest in a Pyrex conical flask for your starters, so the starter wort doesn't need transferring until after it is innocculated.

 

[Rasher]

Liquid to liquid transfers are always the most risky, especially if the actions include pouring rather than using a pipette. It is easy to miss a step or introduce something airbourne during each transfer. In the labs I worked in we used to do solid to liquid transfers on the lab bench, but all liquid to liquid transfers were done in a microbiological cabinet that had been sterilized by UV and had microbe-free air. And we never poured anything, it was just too risky.

Your process would have involved three of these 'pouring' transfers. You can remove one of those transfers by making your starter culture in your FV and racking the wort on top on brewday. Or, invest in a Pyrex conical flask for your starters, so the starter wort doesn't need transferring until after it is innocculated.

Thanks for the info. I suppose something could've contaminated it as I was pouring it into the bottle. Unfortunately my local homebrew shop doesn't carry any pyrex conical flasks, but I do plan to get one in the future.

If I put the yeast starter into the FV wouldn't I have to pour it in still?

 

[foxbat]

Its often said that microbiology scientists are surprised that beer gets brewed at all but the fact is that with the huge quantities of yeast that we pitch, and the aggressive way that yeast acts to shut out the competition, we usually get away with it.

The strain you're using has the diastaticus gene. It will be a little 'funky'. But if you're in any doubt then don't pitch it. I always taste a starter and have chucked a few for similar reasons.

 

[Rasher]

Its often said that microbiology scientists are surprised that beer gets brewed at all but the fact is that with the huge quantities of yeast that we pitch, and the aggressive way that yeast acts to shut out the competition, we usually get away with it.

The strain you're using has the diastaticus gene. It will be a little 'funky'. But if you're in any doubt then don't pitch it. I always taste a starter and have chucked a few for similar reasons.

Yeah I suppose I don't really know what it should taste like. I let my housemate taste it and he doesn't think that anything is wrong, and I half agree with him. The other half of me is a bit unsure though. Also I thought it was strange that it didn't really clear at all in the fridge like I had hoped it would, that was the main thing that was making me unsure at first.

 

[DocAnna]

I've only done three starters so I'm no expert, but the vinegar taste does sound worryingly like an infection, which means you've been really unlucky. My only question is about the starting gravity of the starter wort, I've aimed for 1.04 using DME each time though in each case it was in glass rather than plastic. Given the risk to a whole batch I'd be inclined to make the starter again, sorry.

Anna

 

[Rasher]

I've only done three starters so I'm no expert, but the vinegar taste does sound worryingly like an infection, which means you've been really unlucky. My only question is about the starting gravity of the starter wort, I've aimed for 1.04 using DME each time though in each case it was in glass rather than plastic. Given the risk to a whole batch I'd be inclined to make the starter again, sorry.

Anna

The original gravity of the starter wort was 1.036 and it's volume was around 1.2 litres. The vinegar taste isn't too strong but I do think there's a hint of it in there.

I have no problem buying another pack of yeast and being extra careful with sanitation, but I was quite thorough the first time.

Thanks for the reply!

 

[Galena]

Buy yourself a decent Erlenmeyer flask, I would suggest a 3 litre one as the time will come when you want to step up to a 2 litre starter and then you will need the headroom. FLASK
Use a yeast starter calculator like Homebrew Dad's calculator. Geerally you want to make a 1.040 OG starter, so that is 100gms DME per litre of water.
After you have boiled the water and DME in the flask for 10 mins, then cooled to room temperature make sure the yeast is not warmer than the water/DME as this can stress the yeast. If you don't use a stirrer plate then shake it really well to aerate, then pitch the yeast. I tend to keep it aerated for 28 hours and then another 18 hours without aeration before I put it in the fridge. If you use the calculator then you can overbuild by 100bn cells and put that in a Mason Jar for the next brew.
This is my favourite video on how to make starter... VIDEO

 

[Rochefort]

If I put the yeast starter into the FV wouldn't I have to pour it in still?

Your current method (3 open air transfers by pouring):
Make starter wort -> pour it into a bottle -> pour yeast into bottle -> pour starter into FV

Alternatives (2 open air transfers by pouring):
Make starter wort -> pour it into FV -> pour yeast into FV
or
Make starter wort in conical flask -> pour yeast into flask -> pour starter into FV

 

[Rasher]

Buy yourself a decent Erlenmeyer flask, I would suggest a 3 litre one as the time will come when you want to step up to a 2 litre starter and then you will need the headroom. FLASK
Use a yeast starter calculator like Homebrew Dad's calculator. Geerally you want to make a 1.040 OG starter, so that is 100gms DME per litre of water.
After you have boiled the water and DME in the flask for 10 mins, then cooled to room temperature make sure the yeast is not warmer than the water/DME as this can stress the yeast. If you don't use a stirrer plate then shake it really well to aerate, then pitch the yeast. I tend to keep it aerated for 28 hours and then another 18 hours without aeration before I put it in the fridge. If you use the calculator then you can overbuild by 100bn cells and put that in a Mason Jar for the next brew.
This is my favourite video on how to make starter... VIDEO

Thanks for the info! I'm going to invest in a Erlenmeyer flask and a stir plate for my next attempt, so brew day is going to be called off for a week or two. Fingers crossed nothing goes bad for me on the next attempt.

 

[Rasher]

Your current method (3 open air transfers by pouring):
Make starter wort -> pour it into a bottle -> pour yeast into bottle -> pour starter into FV

Alternatives (2 open air transfers by pouring):
Make starter wort -> pour it into FV -> pour yeast into FV
or
Make starter wort in conical flask -> pour yeast into flask -> pour starter into FV

I suppose that's the thing that confuses me then. If it got infected on the pour into the bottle, then why wouldn't it get infected with the pour into the fermenter? And surely I have to aerate it so why wouldn't it get infected when it's just made in a conical flask because I still have to slosh air through it?

That being said I'm going to try again with a conical flask and hopefully it turns out well.

 

[Galena]

I suppose that's the thing that confuses me then. If it got infected on the pour into the bottle, then why wouldn't it get infected with the pour into the fermenter? And surely I have to aerate it so why wouldn't it get infected when it's just made in a conical flask because I still have to slosh air through it?

That being said I'm going to try again with a conical flask and hopefully it turns out well.

All my yeast starters have been made in an Erlanmeyer flask and all require a through air transfer and I have never yet had an infection.
You just need to take care, I sanitise everything, I have a spray bottle of Starsan to hand and spray liberally the foil and top of the flask before, during and after the transfer. I always overbuild and put some by in a mason jar which has been steralised in a pressure cooker beforehand.
As said above reduce your transfers as much as you can. Having said that if I need to build up a starter for a stronger brew, like I did yesterday I only have one flask so it has to go via a plastic bottle, but so far so good.
This time of year I don't think is too bad but a in the summer when there are more airborne wild yeasts about and fruit flies then more care is necessary.
You could of course try and do as they do when making slants and make the transfer near a flame so as to draw the air upwards, I have never tried it but it is a laboratory technique that I assume must help

 

[Rochefort]

I suppose that's the thing that confuses me then. If it got infected on the pour into the bottle, then why wouldn't it get infected with the pour into the fermenter? And surely I have to aerate it so why wouldn't it get infected when it's just made in a conical flask because I still have to slosh air through it?

That being said I'm going to try again with a conical flask and hopefully it turns out well.

The risk of infection involves a rare event that increases in likelihood with the complexity of what you are trying to do and the time you expose your wort to infection - the fewer transfers, the less chance of infection; the fewer items that need to be sanitised (eg the flask, which is heated directly), the less chance of infection through making a mistake when sanitising (which is, after all, not the same as sterilising).

Take a look at the light coming from a window on a sunny day - you will see little dust motes dancing around in the shaft of light. These have bacteria and fungi on them which can enter any open vessel when they fall downwards. This is why you put a loose screwcap or piece of foil on top of the starter - it allows you to shake it and let oxygen in without those dust particles entering. It is also the reason for working near a flame/updraft - what goes up on a convection current is less likely to fall back down where you are working.