Crap in starter
- Thread starter Goodbeer
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Yes, doubt there is anything wrong with it, though it is a little clear for a starter. The amount of DME is a little low, it is a good idea to add a yeast nutrient to your starter, and best to pitch it when it is at it's most vigorous. BTW - starters should be made at the high 20s - maximum activity whilst avoiding the bacterial danger range above 30C, this will have no adverse affect on the flavour of your final beer.
Finally, I strongly recommend not crapping in your starters...
Finally, I strongly recommend not crapping in your starters...
It's good not to over simplify when talking about yeast starters, its a subject with a lot of room for getting things seriously wrong and actually doing more harm than good.
The "Optimum" SG for a starter is probably 1.036-1.038, 1.040 is pretty close, 100g of DME in 900g of water would be 10oP (10 Plato or 10% extract) or 1.040, too much higher and you encounter the Crabtree Effect (or more properly its effects). Some modern commercial propagation systems are starting at 2% extract and rely on continuous feeding and aeration to get really high populations of healthy yeast (>300m C/mL).
Without continuous aeration there is a very real limit on just how much the yeast can reproduce, probably somewhere around 80million cells/mL, with just initial aeration, which means that a 2L starter at best would contain 1.6*10^11. With continuous aeration might get up to 200million c/mL, but around 150m c/mL is probably a safer bet.
As for the temperature, generally warmer is better than cooler for rate of reproduction, probably around 25oC being ideal. Where you have to be a bit careful is when pitching, you don't want a more than 5oC difference between the pitch and the wort or thermal shock will kill a lot of your yeast, a process called attemperation is appropriate, adding small portions of wort to the starter to get the temperature of the two close enough for pitching.
One of the biggest problems with starters that don't have a really good balance of nutrients and aeration, is that they can result in a large population of yeast with very depleted glycogen reserves and not in really good condition to start fermenting your wort.
Mark
The "Optimum" SG for a starter is probably 1.036-1.038, 1.040 is pretty close, 100g of DME in 900g of water would be 10oP (10 Plato or 10% extract) or 1.040, too much higher and you encounter the Crabtree Effect (or more properly its effects). Some modern commercial propagation systems are starting at 2% extract and rely on continuous feeding and aeration to get really high populations of healthy yeast (>300m C/mL).
Without continuous aeration there is a very real limit on just how much the yeast can reproduce, probably somewhere around 80million cells/mL, with just initial aeration, which means that a 2L starter at best would contain 1.6*10^11. With continuous aeration might get up to 200million c/mL, but around 150m c/mL is probably a safer bet.
As for the temperature, generally warmer is better than cooler for rate of reproduction, probably around 25oC being ideal. Where you have to be a bit careful is when pitching, you don't want a more than 5oC difference between the pitch and the wort or thermal shock will kill a lot of your yeast, a process called attemperation is appropriate, adding small portions of wort to the starter to get the temperature of the two close enough for pitching.
One of the biggest problems with starters that don't have a really good balance of nutrients and aeration, is that they can result in a large population of yeast with very depleted glycogen reserves and not in really good condition to start fermenting your wort.
Mark
Danscraftbeer
Well-Known Member
Agree to strict requirements and techniques with yeast starters.
Added to that different yeasts can have very different visual characteristics too.
Eg. Say your stir bar throws off and your yeast kinda settles. Then get it stiring again. Some yeasts are just cloudy as standard and some are clumpy, in different clumpy ways. Or stringy, or with a curdled look. Its something even more interesting about differing yeast character etc.
Added to that different yeasts can have very different visual characteristics too.
Eg. Say your stir bar throws off and your yeast kinda settles. Then get it stiring again. Some yeasts are just cloudy as standard and some are clumpy, in different clumpy ways. Or stringy, or with a curdled look. Its something even more interesting about differing yeast character etc.
