Starter question...

[Rob2010SS]

So, I was thinking about something in regards to a starter I'm doing for a lager. This starter started out as a 1.5L starter. It's chilling right now and will be stepped up to a 5L starter using 544g DME.

What I started thinking about is this...

If I boil up 5L of water and add the 544g DME to that, I'm going to have way more than 5L starter. Is the starter volume that calculators spit out the total volume once you boil and add DME or is it the volume pre-boil and pre-DME addition?

 

[Vale71]

You'll have a surprisingly small volume increase compared to how much DME you think you've added. Firstly, DME is a very fine powder which means a lot of its apparent volume is just made of air. Secondly, like most solutes extract will increase the solution's volume by much less than its actual volume.
As to the calculators: who knows? I wouldn't sweat the small difference anyway considering that calculators are just guesswork in any case. What's really important is that you can deal with the volume without having half the starter spill over.

 

[Rob2010SS]

You'll have a surprisingly small volume increase compared to how much DME you think you've added. Firstly, DME is a very fine powder which means a lot of its apparent volume is just made of air. Secondly, like most solutes extract will increase the solution's volume by much less than its actual volume.
As to the calculators: who knows? I wouldn't sweat the small difference anyway considering that calculators are just guesswork in any case. What's really important is that you can deal with the volume without having half the starter spill over.

That was really my concern. If I filled the flask up with 5L of water and added all that DME, would I have a spill over. I was thinking I would fill the flask with 3 or 4L, add the DME and get it mixed into solution, then top up to 5L from there to avoid the spilling over.

Still going to be questionable though due to the amount of yeast I'm adding from the first step. We'll see how that goes.

Thanks for the input @Vale71

 

[cswant88]

If I'm doing a 3L starter, then 3L of water goes into the pot with the required amount of DME and a little yeast nutrient, boil for 10min to sterilize, then into ice bath to cool before going into the flask on the stir plate. I usually end up with the exact amount or slightly less than the starting volume of water. DME will have a negligible impact on your total volume.

It sounds like you're adding boiling water straight into the glass? If so, be careful with that. I know a lot of the lab grade borosilicate glassware out there can supposedly handle it, but just because it theoretically can doesn't mean that you should. In my mind, large rapid temperature changes and glass don't mix, period. Even so, I still see people that are surprised when they pull a flask full of boiling liquid off a hot plate, then drop it into and ice bath just to have it burst into a thousand pieces. Some may claim they've been doing it for years without issue, in my opinion, they've just been lucky.

 

[Rob2010SS]

That's kind of what I was looking for - what kind of impact on volume would DME have. Thanks for the info.

Yeah, so for a while, I would always boil in a pot, cool in an ice bath in the sink down to pitching temp, and pour it into the flask. I had always stayed away from boiling in the flask for the exact reason you mention. I've seen WAY too many pictures of broken flasks on stoves and what not. I'm not sure what convinced me to do otherwise - maybe just the ease of the whole thing - but I started boiling in the flask and chilling in the flask recently. Only done it twice so far, it is a little nerve wracking. One of those times, I took the flask off of the stove and put it it a luke warm water bath in one side of the sink and let it sit there for a few minutes before transferring it over to the cold water side of the sink. I dont' use ice right away, just the coldest water that comes out of the sink. I let it sit in there for 10 min or so, then I'll add ice packs from the freezer to drop it a little more, and then finally to get it to pitching temp, I"ll add in a pitcher of ice and let it sit. The other time, I just put it right in the cold water side and skipped the warm water step. Not sure if I'll stick with the boiling in the flask or not.

 

[Gnomebrewer]

Mix the DME with water then make up to 5L, then boil that. The numbers given in calculators is for DME in a total volume of solution (not the amount of water added) which are, as already noted by vale, surprisingly similar. If the volume's going to be too high with the yeast from the first step, make a 4.8L starter instead of 5L.

 

[jddevinn]

Volume is solution volume with the DME mixed in.

 

[catalanotte]

So, I was thinking about something in regards to a starter I'm doing for a lager. This starter started out as a 1.5L starter. It's chilling right now and will be stepped up to a 5L starter using 544g DME.

What I started thinking about is this...

If I boil up 5L of water and add the 544g DME to that, I'm going to have way more than 5L starter. Is the starter volume that calculators spit out the total volume once you boil and add DME or is it the volume pre-boil and pre-DME addition?

544g of DME will take up about 350ml of volume. You can reduce you water accordingly, but it’s a pretty minor difference.

 

[jimyoung]

I agree with everyone here.. There are so many variables already in play, that your job with a starter is to try and just get within the ballpark. It's certainly not precise and doesn't even consider ambient temperature, etc. So to answer your question, I wouldn't sweat it

 

[Rob2010SS]

544g of DME will take up about 350ml of volume. You can reduce you water accordingly, but it’s a pretty minor difference.

Thanks! That helps!