Right. It's not just a matter of natural selection - yeast that are raised in the absence of maltose can lose the capacity to produce the necessary enzymes, probably due to altered gene expression.
Starter Ingredients: Cheap White Sugar + Nutrients?
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Right. It's not just a matter of natural selection - yeast that are raised in the absence of maltose can lose the capacity to produce the necessary enzymes, probably due to altered gene expression.
You know the old adage, use it or lose it. This isn't really selection but lack thereof. If we don't demand something of a yeast cell, next time we ask them for it it might not be there. The selection happens when we ask for it again. I know its a dirty word in some circles but this is how evolution works. Lots of different things lead to changes in traits over time. We see it faster in yeast because the generation time is 2-3 hours instead of 20 years.
The point was made in an earlier post that this doesn't have to happen through permanent mutation but cells can just get used to one growth condition or another. If they are used to one it can take them longer than usual to get going on another. My understanding is that in the case of maltose fermentation this shouldn't be an issue, induction of the enzymes is pretty fast. But I don't know about the rest of the nutrient conditions in wort.
Another point, if you start out with many cells than the probability of a mutant taking over a population due to a growth advantage is small, if you start with just one cell or a few, it becomes much greater.
The point was made in an earlier post that this doesn't have to happen through permanent mutation but cells can just get used to one growth condition or another. If they are used to one it can take them longer than usual to get going on another. My understanding is that in the case of maltose fermentation this shouldn't be an issue, induction of the enzymes is pretty fast. But I don't know about the rest of the nutrient conditions in wort.
Another point, if you start out with many cells than the probability of a mutant taking over a population due to a growth advantage is small, if you start with just one cell or a few, it becomes much greater.
I ran across this article earlier today on diacetyl production in beer.
http://morebeer.com/brewingtechniques/library/backissues/issue1.2/fix.html
The author talks about a lot of different causes for it, but one of them jumped out at me, so I wanted to resurrect this thread in case anyone else was interested. The entire article is a great read, but it may be a little hard to understand for readers without a biochemistry or organic background. I've tried to summarize it here:
https://www.homebrewtalk.com/f128/c...protein-energy-298164/index2.html#post4228721
The major point which pertains to our discussion here was his experiments with yeast grown on dextrose-sucrose rich media. As one would expect, the culture growth was very rapid, but the yeast performed unacceptably during fermentation and demonstrated a poor uptake of valine which led to large increases in diacetyl in the finished product.
Hope this helps.
http://morebeer.com/brewingtechniques/library/backissues/issue1.2/fix.html
The author talks about a lot of different causes for it, but one of them jumped out at me, so I wanted to resurrect this thread in case anyone else was interested. The entire article is a great read, but it may be a little hard to understand for readers without a biochemistry or organic background. I've tried to summarize it here:
https://www.homebrewtalk.com/f128/c...protein-energy-298164/index2.html#post4228721
The major point which pertains to our discussion here was his experiments with yeast grown on dextrose-sucrose rich media. As one would expect, the culture growth was very rapid, but the yeast performed unacceptably during fermentation and demonstrated a poor uptake of valine which led to large increases in diacetyl in the finished product.
Hope this helps.
iambeer
Well-Known Member
I don't keep yeast for long. Never more than two beers. After one beer, I keep the 'cleaned' slurry because it's easy and fine. After thinking long and hard about this, I decided to go with this method:
As far as starters from the original yeast sample I purchase, I don't see any harm in feeding it simple sugar. I have began doing this, and it seems fine.. It seems to multiply at ease. Like another poster said, it apparently does not mutate swiftly into a yeast that will no longer be able to process maltose. That is bogus unless you keep generations of the same yeast.
I am not worried about the long term effects of yeast mutation because I will eventually buy a new sample every so and so months.
As far as starters from the original yeast sample I purchase, I don't see any harm in feeding it simple sugar. I have began doing this, and it seems fine.. It seems to multiply at ease. Like another poster said, it apparently does not mutate swiftly into a yeast that will no longer be able to process maltose. That is bogus unless you keep generations of the same yeast.
I am not worried about the long term effects of yeast mutation because I will eventually buy a new sample every so and so months.
You should read that article I linked to - it specifically mentions making starters with sucrose. It's not about how much multiplication you get - it's about the health of the cells. I'm just surprised that a guy that wanted real primary information is now willing to ignore it because "it seems fine".
Part of homebrewing is the freedom to do what you like. I wouldn't recommend making starters from table sugar. None of the research into brewing science I've seen supports that idea either and there is plenty that says it's unwise, produces off-flavors, and in general is a bad practice. But, you're free to do what you like.
Justintoxicated
Well-Known Member
So Basically, using table sugar does not get the yeasts creative juices flowing? get it? 
So Basically, using table sugar does not get the yeasts creative juices flowing? get it?
Not sure what you mean, but using table sugar as a medium for growing a yeast starter is a bad idea and does not yield the same quality of finished product. I'm not sure why anyone would choose to use sucrose to make a yeast starter in light of that fact.
If an athlete is runner, why would he train in a swimming pool? Olympic analogy (??)
Yes he will build strength but in mostly the wrong areas.
Yes it helps them become stronger.
Same thing. Grow you yeast in a similar environment (gravity) as your final brew.
I start at 1.040 , decant, and up it to 1.049 depending on gravity of my brew.
If you want to use simple sugars. Go ahead. If you like your product, that's what counts.
Good luck.
Yes he will build strength but in mostly the wrong areas.
Yes it helps them become stronger.
Same thing. Grow you yeast in a similar environment (gravity) as your final brew.
I start at 1.040 , decant, and up it to 1.049 depending on gravity of my brew.
If you want to use simple sugars. Go ahead. If you like your product, that's what counts.
Good luck.
Bierliebhaber
Well-Known Member
I believe the analogy would be more akin to cigarettes and alcohol vs pre-natal vitamins...a baby will come out either way, but how will it function?
DrummerBoySeth
Well-Known Member
The analogy I prefer is giving a child dessert before making him eat his vegetables. When you give the yeast simple sugars like sucrose first (dessert) then they get all fat and happy on all that sugar and do not want to eat their maltose (vegetables)
However, if you make the child eat the broccoli first, then they will still want the ice cream! It just does not work the other way around. I do not know many children who are willing to eat broccoli after feasting on ice cream.
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