Starter Aeration

[oldbugman]

Yumm, looks like a great breaky beer kaboody :icon_chickcheers:

You could spread that on your toast.

 

[reVoxAHB]

kabooby's blown starter got me thinking about vessels (and airlocking which floppinab mentioned).

I use 5L glass demijohns, bunged with hose running to a jar of diluted iodophor. I use a clothes line peg to secure the hose to jar, that way i can pickup the starter whenever I pass it, etc. giving it a brief and gentle swirl. The demijohn stays airlocked the whole time, and the 5L size allows for plenty of head-room, even when stepped to 3 or 4L. Plus I'm a fan of glass; bonus.

I aerate the starter wort before pitching (3-5 mins of vigourous shaking) and only swirl throughout. I try to let the yeast work through the starter and use within 24 hours (after completion)- pouring off the starter wort to pitch. I occasionally cold crash, if I have the time.. and if the starter is at high krausen (again, just a timing issue) I'll pitch the full starter. Been doing it this way for several years and never had an issue with oxidation or otherwise.

Interesting information Screwtop, regarding stir-plates.. glad you got it sorted. I wouldn't have thought a stir-plate could oxidise yeast, certainly not enough to negatively affect a full batch... well there you go. Ya learn something new every day on AHB :icon_cheers:

reVox

 

[Screwtop]

kabooby's blown starter got me thinking about vessels (and airlocking which floppinab mentioned).

I use 5L glass demijohns, bunged with hose running to a jar of diluted iodophor. I use a clothes line peg to secure the hose to jar, that way i can pickup the starter whenever I pass it, etc. giving it a brief and gentle swirl. The demijohn stays airlocked the whole time, and the 5L size allows for plenty of head-room, even when stepped to 3 or 4L. Plus I'm a fan of glass; bonus.

I aerate the starter wort before pitching (3-5 mins of vigourous shaking) and only swirl throughout. I try to let the yeast work through the starter and use within 24 hours (after completion)- pouring off the starter wort to pitch. I occasionally cold crash, if I have the time.. and if the starter is at high krausen (again, just a timing issue) I'll pitch the full starter. Been doing it this way for several years and never had an issue with oxidation or otherwise.

Interesting information Screwtop, regarding stir-plates.. glad you got it sorted. I wouldn't have thought a stir-plate could oxidise yeast, certainly not enough to negatively affect a full batch... well there you go. Ya learn something new every day on AHB :icon_cheers:

reVox

Revox, I was blaming everybody, the yeast companies, AP for taking too long to deliver, retailers for poor storage and also yeast not being fresh. Think the majority of the problem lay in the fact that I had it on the stir plate too long. Sometimes 3 days and also at room temp and in clear glass, a real recipe for disaster when you think about it. Now I keep my starters in the ferm fridge at ferm temps, just a little O2 and I watch the gravity, when they have reached about half expected attenuation I pitch while still active. Also where possible I use wort from the batch, instead of DME. Dry yeast is a lot less of a hassle, don't use much liquid yeast these days with the good dried yeasts now available.

The 6L of wort in the fermenter on the left is part of the batch in the fermenter on the right, it was crash chilled in the freezer and the yeast pitched, the fermenter on the right has 20L of wort which still has not reached pitching temp of 10C yet. The flash in front has 2L of a previous batch which was frozen then thawed for use and pitched at 10C, it is now 8.4 Brix




Cheers,

Screwy

 

[reVoxAHB]

Revox, I was blaming everybody, the yeast companies, AP for taking too long to deliver, retailers for poor storage and also yeast not being fresh. Think the majority of the problem lay in the fact that I had it on the stir plate too long. Sometimes 3 days and also at room temp and in clear glass, a real recipe for disaster when you think about it. Now I keep my starters in the ferm fridge at ferm temps, just a little O2 and I watch the gravity, when they have reached about half expected attenuation I pitch while still active. Also where possible I use wort from the batch, instead of DME. Dry yeast is a lot less of a hassle, don't use much liquid yeast these days with the good dried yeasts now available.

Screwy

Yep. I definitely keep mine in the ferm fridge, too. I've been trying to use wort from a batch as well, over DME.. haven't really worked out a good system as of yet (aside from the obvious which is to get a starter going on a brew day). I think doc freezes a few extra L of 1.040, for starter use at a later date.

So pitching at half expected attenuation means it's past-krausen? Palmer suggests optimum time to pitch is 18 hours after activity has peaked, "while the starter builds up its trehalose and glycogen reserves." I'm guessing this is approx. half-attenuation? Otherwise, he suggests pitching about a day or two after the starter has settled out, depending on temperature.

Cheers on the tips and things to watch out for, across the board.

reVox

 

[Screwtop]

So pitching at half expected attenuation means it's past-krausen? Palmer suggests optimum time to pitch is 18 hours after activity has peaked

No Idea Revox, just what I've found. Depends on the starting gravity and yeast strain, it's just that I've found that the gravity has been around that mark for most of the starters so far when at full activity. The time can vary, so I just go with the gravity reading The one on the left was OG 67 at AA% of 73 for this yeast it should finish at SG 17 so I need for it to drop by 25 to be halfway done, so will pitch it at SG 42.

Screwy

 

[reVoxAHB]

No Idea Revox, just what I've found. Depends on the starting gravity and yeast strain, it's just that I've found that the gravity has been around that mark for most of the starters so far when at full activity. The time can vary, so I just go with the gravity reading The one on the left was OG 67 at AA% of 73 for this yeast it should finish at SG 17 so I need for it to drop by 25 to be halfway done, so will pitch it at SG 42.

Screwy

Cool. Figured there would be too many variables to nail down a general time-line vs. apparent attenuation profile. Your actively following the AA% prior to pitching, brings the starter into the realm of it being controlled, and is therefore repeatable (to result). Will definitely try this with my next starters. I've kind of blindly been doing, "whatever" and it all works.. but!

Wanted to add I've been using Wyeast Yeast Nutrient for the better part of a year, too in both my starter wort and batch wort. Seems to help in reducing the lag phase.. but is beneficial across the board. A $10 vile goes a l o n g way.

reVox

 

[Sammus]

I let my yeast sit stirring for days and dont get any off flavours, I think a lot of people run their stir plates too fast, I've seen pics of then will big vortexes down to the stir bar in their flask. I think your bound to have problems then, but with a speed control on mine I set it low enough just to stop the yeast dropping out and you can barely see any stirring activity on the surface, but look in the side and you notice all the yeasties staying in suspension. I'm pretty sure once the fermentation starts theres a nice blanket of CO2 that stops from oxidising... thats my experience anyway, maybe I just cant taste 1L of oxidized beer in 25L total.