Help I Messed UP!
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Help Support Winemaking Talk - Winemaking Forum:
JimCook
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PeterZ,
Between the link above and the other article that is mentioned, it's difficult to find any solid science here. Can you let me know if you come up with any scientific specifics on this topic. I'm sure the vitality of the yeast and their lifecycle will be a heavy factor in this. It's kind of a 'how much wood could a woodchuck chuck if a woodchuck could chuck wood' kind of question - if the first generation of yeast are alive and kicking, how much sugar can they (and any of their children from the starter) eat before they kick the proverbial bucket? Jack Keller notes that he has seen dead yeastsediment drop out after as much time astwo months after stabilization, although this isn't to say they were or were not viable consumers during that time.
I know that sulfite normally stupifies more than itkills yeast cells, causing a disruption in their normal activities to reduce their 'productivity'- this combined with K-sorbate causes a shock and reproductive block to convince the yeast to stop activity, so it's not that K-sorbate isn't working when yeast are active.
While the effect pH limit of K-sorbate caps out at 6.5 and it's more effective in acidic environments, the pH of the wine shouldn't be making drastic jumps, so I can't see that being a realistic factor since the wine should be somewhere around 3.0-4.0 pH regardless.
I think it comes back to what you and appleman said about adding starters with a good volume of yeast that are alive so they can just start eating away, even if their reproduction is potentially hampered.
All things regardless, a happy ending is a good ending.
- Jim
Between the link above and the other article that is mentioned, it's difficult to find any solid science here. Can you let me know if you come up with any scientific specifics on this topic. I'm sure the vitality of the yeast and their lifecycle will be a heavy factor in this. It's kind of a 'how much wood could a woodchuck chuck if a woodchuck could chuck wood' kind of question - if the first generation of yeast are alive and kicking, how much sugar can they (and any of their children from the starter) eat before they kick the proverbial bucket? Jack Keller notes that he has seen dead yeastsediment drop out after as much time astwo months after stabilization, although this isn't to say they were or were not viable consumers during that time.
I know that sulfite normally stupifies more than itkills yeast cells, causing a disruption in their normal activities to reduce their 'productivity'- this combined with K-sorbate causes a shock and reproductive block to convince the yeast to stop activity, so it's not that K-sorbate isn't working when yeast are active.
While the effect pH limit of K-sorbate caps out at 6.5 and it's more effective in acidic environments, the pH of the wine shouldn't be making drastic jumps, so I can't see that being a realistic factor since the wine should be somewhere around 3.0-4.0 pH regardless.
I think it comes back to what you and appleman said about adding starters with a good volume of yeast that are alive so they can just start eating away, even if their reproduction is potentially hampered.
All things regardless, a happy ending is a good ending.
- Jim
PeterZ
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Jim,
I really haven't researched this extensively, but as was stated earlier in this thread, potassium sorbate is birth control for yeast. It does not inhibit their fermentation of sugar into alcohol. In addition, yeast reproduction is also inhibited by high levels of sulfite, as O2 is necessary for reproduction, albeit in very small quantities, and sulfite binds O2 and removes it from solution.
"Jack Keller notes that he has seen dead yeastsediment drop out after as much time astwo months after stabilization"
I take this with a grain of salt. Unless he has examined the sediment under a high power microscope, there is no way to determine if this is or was active yeast cells or just micro solids that coagulated into macro solids and settled. The human eye can only detect particles so small. What looks clear may not be. It takes very sophisticated equipment to determine the actual turbidity of an almost clear liquid. These instruments, which cost thousands of dollars, are used by municipal utilities using surface (river and lake) water for their potable water source to evaluate the performance of their clarification procedures.
For true scientific information on the chemistry and biochemistry of potassium sorbate the first place I would look is the Univ. of CA Davis. They are at the center of winemaking research.
I really haven't researched this extensively, but as was stated earlier in this thread, potassium sorbate is birth control for yeast. It does not inhibit their fermentation of sugar into alcohol. In addition, yeast reproduction is also inhibited by high levels of sulfite, as O2 is necessary for reproduction, albeit in very small quantities, and sulfite binds O2 and removes it from solution.
"Jack Keller notes that he has seen dead yeastsediment drop out after as much time astwo months after stabilization"
I take this with a grain of salt. Unless he has examined the sediment under a high power microscope, there is no way to determine if this is or was active yeast cells or just micro solids that coagulated into macro solids and settled. The human eye can only detect particles so small. What looks clear may not be. It takes very sophisticated equipment to determine the actual turbidity of an almost clear liquid. These instruments, which cost thousands of dollars, are used by municipal utilities using surface (river and lake) water for their potable water source to evaluate the performance of their clarification procedures.
For true scientific information on the chemistry and biochemistry of potassium sorbate the first place I would look is the Univ. of CA Davis. They are at the center of winemaking research.
