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Rehydration_Starter_05_lo.jpg
RdeVjun

Rehydration_Starter_05_lo.jpg

So, the Schott bottles are now approaching 30 degC, get your dried yeast out of the fridge and allow it to reach room temperature for a while before the next step. We don't want to temperature- shock the yeast if we can avoid it, better to let them acclimatise for a longer rather than a shorter period.So, once you're happy that the plain water is around the right temperature and the dried yeast has warmed up, carefully open the bottle and the yeast and tip it in. Be careful how you handle the lid, you don't want to put it down the wrong way up in a puddle of something unmentionable and also try not to breathe all over it or the open yeast sachet, I know its very exciting but do try to control yourself at this stage. Recap the bottle, don't give it a swirl to suspend the yeast, just allow to stand for about half an hour.One yeast manufacturer recommends:QUOTE Sprinkle the yeast on the surface of 10 times its weight of clean, sterilized (boiled) water at 3035C.Do not use wort, or distilled or reverse osmosis water, as loss in viability will result. DO NOT STIR.Leave undisturbed for 15 minutes, then stir to suspend yeast completely, and leave it for 5 moreminutes at 3035C. Then adjust temperature to that of the wort and inoculate without delay. (Sorry, I'm unsure of attribution, when I find it I'll credit the manufacturer. Source AHB's:[post="http://www.aussiehomebrewer.com/forum/index.php?showtopic=31661&view=findpost&p=443587"]Nottingham Yeast - Dropping Early[/post])There are many views about precisely how to do this pitching step, particularly the temperature, water composition and stirring process. For mine, there are a few important points:* Rehydrate dried yeast with tapwater that is as sterile as it can be made by the brewer and cooled to 25-35 degC.* Once it is obviously out of its dormant phase (i.e. dried), through the lag phase and reproducing (foaming is evidence of this), then pitching into a starter wort at about the same temperature will help to reduce shock and it will then be eager to start consuming carbohydrates. This needs to be done before the yeast runs out of glycogen while in the rehydration solution.A useful reference: The Brewer's HandbookIt may be worthwhile towards the end of the cooling phase to open the sealed bottle and let it sit open for a few minutes, reseal and shake it up vigorously to reoxygenate the water, perhaps even doing this a few times. So far I haven't done this and it would be optional, but also a possible source of infection. I am unsure if the boiling process will deoxygenate a sealed bottle, it probably will if it is not sealed during boiling. Coming out of the dormant phase, yeast do require oxygen to assimilate glycogen reserves.
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Rehydrate dried yeast & progress through a starter
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