having trouble grasping concept of esters as well as lag time of fermentation do yeast actually divide at lag time and why does underpitching cause more esters and byproducts also can you make more eaters and without other byproducts
Esters and lag time
- Thread starter RNBEERGUY
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What I've read, RN, is that the first phase of yeast activity after pitching is reproduction - they are gathering strength for the task ahead of them. Pitching a larger cell count of yeast with high vitality into a wort that has everything they need will lead to shorter lag times.
Again, from reading, my understanding is that underpitching stresses the yeast and leads to production of more compounds that lead to what may be considered off-flavors, such as esters. Ester production can be increased for other reasons though, too - in brewing, there seems to seldom be a one-to-one correlation. For example, if you want more esters in your ESB, you can raise the fermentation temperature a little. Or switch to a yeast that is more prone to ester production.
Again, from reading, my understanding is that underpitching stresses the yeast and leads to production of more compounds that lead to what may be considered off-flavors, such as esters. Ester production can be increased for other reasons though, too - in brewing, there seems to seldom be a one-to-one correlation. For example, if you want more esters in your ESB, you can raise the fermentation temperature a little. Or switch to a yeast that is more prone to ester production.
archthered
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Keep in mind that yeast are very complex organisms that can give you the same results under different circumstances and there are exceptions to every rule of brewing. We don't actually always understand exactly what they are doing, why and what compounds are being made when. When I say we don't know I don't just mean home brew shlubs like me I mean microbiologist who look at yeast for a living don't always fully understand the processes and why. As a result as Pappers said there are multiple ways to get the same effect. But don't worry too much about these unknowns because the reality is if you do the same thing all the time you will get the same results... more or less.
Everything that follows is based off my understanding of how yeast works which I believe is accurate but the implications and applications of that information, ie when to change temps etc, is not really agreed on and some will undoubtedly argue about how to apply this info, I'm telling you this since your profile suggests you are new and you can understand why you may get different answers after this. Lag is the period during which yeast are assessing the environment, getting used to it, and preparing for a hell of a lot of reproduction. My understanding is that at this time they make very little flavor compounds which is why some swear by pitching a little higher than their fermentation temp. The next thing that happens is the yeast reproduce like crazy, in my experience some consider this part of the lag phase since you can't really see when it switches from lag to early stage exponential growth, the difference is largely academic. This point is when they make lots and lots of flavor compounds and if you are at too high of a temp at this point you can get all kinds of bad stuff, which is why some like to start fermentation at lower temps. You can not see when this happens, if you keep the temp high because it does not matter in the lag phase and wait until you can see krausen start forming it is already too late, do not do that, I'm just explaining why some pitch high and others low. During this time yeast use up alot of oxygen and don't care much about being clean, there metabolism is in high gear and they are not being efficient, they literally make compounds they kick out as waste that they can later use.
As far as esters and underpitching, if you under pitch that means that each yeast cell has to do more dividing in order to get all the food used up so they get more and more unhealthy and as they do so they make more and more off compounds like esters. I think there was more effects of underpitching but I can't rightly remember them now and do not want to give you bad info.
Here is something to read on fermentation if you want. https://byo.com/article/fermentation-time-line/
Everything that follows is based off my understanding of how yeast works which I believe is accurate but the implications and applications of that information, ie when to change temps etc, is not really agreed on and some will undoubtedly argue about how to apply this info, I'm telling you this since your profile suggests you are new and you can understand why you may get different answers after this. Lag is the period during which yeast are assessing the environment, getting used to it, and preparing for a hell of a lot of reproduction. My understanding is that at this time they make very little flavor compounds which is why some swear by pitching a little higher than their fermentation temp. The next thing that happens is the yeast reproduce like crazy, in my experience some consider this part of the lag phase since you can't really see when it switches from lag to early stage exponential growth, the difference is largely academic. This point is when they make lots and lots of flavor compounds and if you are at too high of a temp at this point you can get all kinds of bad stuff, which is why some like to start fermentation at lower temps. You can not see when this happens, if you keep the temp high because it does not matter in the lag phase and wait until you can see krausen start forming it is already too late, do not do that, I'm just explaining why some pitch high and others low. During this time yeast use up alot of oxygen and don't care much about being clean, there metabolism is in high gear and they are not being efficient, they literally make compounds they kick out as waste that they can later use.
As far as esters and underpitching, if you under pitch that means that each yeast cell has to do more dividing in order to get all the food used up so they get more and more unhealthy and as they do so they make more and more off compounds like esters. I think there was more effects of underpitching but I can't rightly remember them now and do not want to give you bad info.
Here is something to read on fermentation if you want. https://byo.com/article/fermentation-time-line/
