GodsStepBrother
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I am trying to understand what exaclty brewers mean when they say yeast is stressed out. What causes them to be stressed out, and how is it that this happens. In brewing Science and Practice I have found some pretty interesting references and wanted to run them by some more experienced members.
The author begins to describe earlier in the book , that to much budding of yeast cells produces a lot of scar tissue on the cell wall of the yeast. This according to him leads an unhealthy cell, and leading to more mutations etc He makes it explicate that, buds may arise from any point on the cell wall. Nevertheless, buds do not arise more than once at the same location. Meaning to much multiplication leads to a lot of what he call fissures, or ring structure containing filaments termed septins. Now I am not to certain what septins are and do not care much. He correlates it to scar tissue, in the remainder of the chapter.
He never mentions why it is scar tissue is to bad for the yeast (beyond the fact that it can lead to mutation and such), could it also be that a yeast cell cannot eat from the point of budding and if it buds enough then it will lead to a malnourished cell?
My other question is regarding Vacuoles. These he describes as intercellular membrane systems. He states, Vacuoles serve as temporary metabolite stores and provide the cell with a mechanism for controlling the concentration of metabolites in other cellular compartments. So am if I am reading right, he means these are almost storage compartments to hold metabolites, in other words food correct? He mentions this about Vacuoles,
Their size and number fluctuates with physiological condition and stage in the cell cycle. When cells are growing in a balanced medium, as is the case during active primary fermentation, they may not be visible. Extensive vacuolation is associated with stress in yeast, especially starvation. Commonly large vacuoles become apparent in late fermentation or in stored pitching yeast.
Now what I find odd about this last statement is he says that extensive vacuolation is associated with stress in yeast, but only later puts an emphasis on starvation as one of the factors. He never defines what he means by stress and its factors, only starvation as the leading one. Now budding and reproducing takes a lot of energy and he admits that yeast will not do it, until it senses enough food around. He gives a time line of each phase the cell goes through. I added it up and it roughly takes about 125 minutes (about two hours) for the splitting of a cell to occur. In which the offspring cell is smaller than the mom, and must wait some more time to grow and do what yeast do.
All of this to leads to a couple of simple questions.
1. If a beer is under pitched does that mean that the constant budding from mother cells creates to much scar tissue leading to malnourished mothers and making half of the yeast population unhealthy as well as mutated offspring?
2. Even though the mother is in a nutrient rich fluid, it reproduces to much that it looses some ability to eat, leading to the formation of vacuoles that it cannot fill with metabolites?
3. When he mentions yeast growing in a balanced median does he mean a good yeast cell ratio to available food, in other words a good pitching rate?
Sorry for writing a book just trying to understand what leads to poor yeast health.
The author begins to describe earlier in the book , that to much budding of yeast cells produces a lot of scar tissue on the cell wall of the yeast. This according to him leads an unhealthy cell, and leading to more mutations etc He makes it explicate that, buds may arise from any point on the cell wall. Nevertheless, buds do not arise more than once at the same location. Meaning to much multiplication leads to a lot of what he call fissures, or ring structure containing filaments termed septins. Now I am not to certain what septins are and do not care much. He correlates it to scar tissue, in the remainder of the chapter.
He never mentions why it is scar tissue is to bad for the yeast (beyond the fact that it can lead to mutation and such), could it also be that a yeast cell cannot eat from the point of budding and if it buds enough then it will lead to a malnourished cell?
My other question is regarding Vacuoles. These he describes as intercellular membrane systems. He states, Vacuoles serve as temporary metabolite stores and provide the cell with a mechanism for controlling the concentration of metabolites in other cellular compartments. So am if I am reading right, he means these are almost storage compartments to hold metabolites, in other words food correct? He mentions this about Vacuoles,
Their size and number fluctuates with physiological condition and stage in the cell cycle. When cells are growing in a balanced medium, as is the case during active primary fermentation, they may not be visible. Extensive vacuolation is associated with stress in yeast, especially starvation. Commonly large vacuoles become apparent in late fermentation or in stored pitching yeast.
Now what I find odd about this last statement is he says that extensive vacuolation is associated with stress in yeast, but only later puts an emphasis on starvation as one of the factors. He never defines what he means by stress and its factors, only starvation as the leading one. Now budding and reproducing takes a lot of energy and he admits that yeast will not do it, until it senses enough food around. He gives a time line of each phase the cell goes through. I added it up and it roughly takes about 125 minutes (about two hours) for the splitting of a cell to occur. In which the offspring cell is smaller than the mom, and must wait some more time to grow and do what yeast do.
All of this to leads to a couple of simple questions.
1. If a beer is under pitched does that mean that the constant budding from mother cells creates to much scar tissue leading to malnourished mothers and making half of the yeast population unhealthy as well as mutated offspring?
2. Even though the mother is in a nutrient rich fluid, it reproduces to much that it looses some ability to eat, leading to the formation of vacuoles that it cannot fill with metabolites?
3. When he mentions yeast growing in a balanced median does he mean a good yeast cell ratio to available food, in other words a good pitching rate?
Sorry for writing a book just trying to understand what leads to poor yeast health.
