DavidP30 Posted March 12, 2012 Share Posted March 12, 2012 I've seen a few times on this forum words to this effect, like a 7g sachet of coopers ale yeast may have trouble munching through 6kg of fermentables, say. What confuses me is, surely that yeast will be as happy as and will multiply like crazy; maybe it will add a day or two to the ferment time, but patience is one of our virtues, right? So I would have thought that you could pretty much pitch 7g of yeast into 23 litres and regardless of what fermentables are in there, it'll go to town and only stop when it has poisoned itself on alcohol. Or munched through the lot. But, there must be a flaw in this somewhere. I'm not sure exactly what it is though. Link to comment Share on other sites More sharing options...
Guest Posted March 12, 2012 Share Posted March 12, 2012 One of the best explanations I have heard with regards to this topic is that of Thirsty Boy so this is in his words....... Its more a matter of tiredness and stress than mutation. The yeast has certain internal resources, that are best built up in the presence of oxygen, abundant nutrients and lack of poison (which both alcohol and C02 are to a yeast). So in your wort, as soon as the yeast have used up all the available oxygen, they are soldiering on, on a combination of what they already have stored up and what they can try to synthesise out of the wort.. which is much harder for them without oxygen. The bigger the beer and the less yeast you pitch - the harder you are asking the yeast to work with the resources they have on hand. A smaller number of cells will have to multiply up to the required level and still have the internal resources to chomp through the amount of sugar you threw at them.. and the bigger the beer, the more hostile an environment you are asking them to do it in. This makes em work really hard - which doesn't necessarily lead to them producing the best flavours and might lead to them actually conking out before they have finished the job - giving you an underattenuated beer and perhaps leftover diacetyl and acetylaldhyde etc. The higher the wort gravity the more yeast you need to chomp through it. 7g coopers yeast will chomp through 23L of a normal wort gravity or less. (normal being around 1040) however, I feel this questionable at times but that is my personal opinion. Link to comment Share on other sites More sharing options...
Guest Posted March 12, 2012 Share Posted March 12, 2012 I made an AIPA on Sat, I wanted to pitch it last night so chucked it in the fridge and started to rehydrate an 11g packet of US-05. As a matter of habbit I always check on Mr Malty how much yeast will be needed... to my horror I discovered that for my OG of 1061 - 23l I needed 1.4 Packets of yeast... damn... Solution was not ideal but a workable one... I had 50ml of rinsed yeast in the fridge and so pitched about 30ml of that as well into the brew... If it were a choice (which it should never come to) I would much rather overpitch than underpitch... In an ideal world it is neither. Yob Link to comment Share on other sites More sharing options...
Guest Posted March 12, 2012 Share Posted March 12, 2012 and the only other way to get around it, if you have the time, is to step up a starter. [cool] Link to comment Share on other sites More sharing options...
Guest Posted March 12, 2012 Share Posted March 12, 2012 Still havnt got round to building that stir plate or i would have stepped up the 50ml and saved the fresh packet[cool] Still, a good experiment with blending my house yeast [roll] Link to comment Share on other sites More sharing options...
PhilboBaggins Posted March 12, 2012 Share Posted March 12, 2012 Bugger. How do you reckon my latest will go? - Pale Ale Kit - 1kg Spray Malt - 250g Dex - Kit yeast Didn't take an OG reading, but with all that malt, will the kit yeast struggle? My last brew was an English Bitter with 1kg malt but without the dex, and that fermented out as far as I know (was about 1012 FG). Link to comment Share on other sites More sharing options...
Guest Posted March 12, 2012 Share Posted March 12, 2012 Yeah it'll be fine [joyful] Link to comment Share on other sites More sharing options...
Guest Posted March 12, 2012 Share Posted March 12, 2012 Any hops? [crying] Please let there be hops[lol] Link to comment Share on other sites More sharing options...
PhilboBaggins Posted March 12, 2012 Share Posted March 12, 2012 Yupp. 25g Nelson Sauvin, steeped for a bit then thrown in in a home made tea bag. Was just listing the fermentables, no need to panic yob [biggrin] Link to comment Share on other sites More sharing options...
DavidP30 Posted March 12, 2012 Author Share Posted March 12, 2012 Blast well my thoery's down the tubes and so maybe is my beer: One tin of Cooper's draught 1kg LDM 1kg BE2 and the yeast that turned up in the tin. I did give the wort a might good aeration though so perhaps I'll struggle over the line? Oh and just to get Yob onside I also added hops :) mm hmm three different types in fact and plan to dry hop with a fourth. Link to comment Share on other sites More sharing options...
Guest Posted March 12, 2012 Share Posted March 12, 2012 David, Have you used Mr Malty? I ALWAYS check my targets with this resource, as noted above, I should probably check earlier and make sure I dont leave myself short of the correct amount to pitch [innocent] I notice IanH's spreadsheet has been made into a sticky over there (AHB) now.. A big help as far as tools to help prepare the required ingredients, was very slack of me not to have prepared in advance and shows that Im getting a little lazy and need to pick up the game... Yob Link to comment Share on other sites More sharing options...
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