double pitching and a starter?

[deputyandy]

Hey guys, brewing a trois pistoles clone this weekend. Using WLP 530 and I went with the double pitching option (2 vials). From mrmalty that should be the right amount of yeast to make a starter 1.092 wort, but I was wondering if I keep the standard starter proportions the same. I have a 2L flask and DME and it just seems like a lot of yeast for a 1.040 starter. Any insight would be helpful.

 

[MalFet]

For me, Mr Malty says 2.5L with 2 vials. I'm not sure what about that sounds incorrect to you, because it sounds about right to me. 1.040 wort is standard because it provides a good compromise between sugar density and yeast stress. When building up from small quantities (from plates or dregs, for example), it makes sense to go lower, but I'm not sure that you'd ever want to go higher.

 

[deputyandy]

I guess I'm just thinking that if ill put a whole lot of yeast from two vials into one starter it'd make sense that the starter needs more fuel to munch on. Since 1.040 is for one vial I assumed you'd need more for 2.

 

[MalFet]

I guess I'm just thinking that if ill put a whole lot of yeast from two vials into one starter it'd make sense that the starter needs more fuel to munch on. Since 1.040 is for one vial I assumed you'd need more for 2.

If you start with two vials, you actually need less sugar than if you only used one. Your main purpose in building a starter is to manufacture yeast. If you start with two vials, you have less manufacturing to do. Yeast has an impressive ability to detect its own population levels and to propagate only to an appropriate level.

In any case, if you wanted more sugars, you would accomplish that by using a larger volume. When you start getting above 1.040, it quickly becomes an osmotically harsh environment for the yeast. That's why it's so much more important to have healthy yeast when pitching into a big beer than with an average sized beer.

 

[BlueZooBrewing]

If you start with two vials, you have less manufacturing to do. Yeast has an impressive ability to detect its own population levels and to propagate only to an appropriate level.

In any case, if you wanted more sugars, you would accomplish that by using a larger volume. When you start getting above 1.040, it quickly becomes an osmotically harsh environment for the yeast.

Theres two parts about this that dont sit quite right for me. With my degree in biology i know how this stuff is supposed to work in theory, but the first thing that you learn in a bio course is that everything depends and nothing follows the textbooks in nature. Im new to the brewing, so if "in nature" certain theories and beliefs get thrown out the window, im happy to learn from the experts, im just curious to learn why.

One, while the yeast is very good at detecting its own population levels, it should also have a very good ability at detecting its environmental conditions. If you have less fermentables in an environment then the yeast wont reproduce to the same degree as if there were more fermentables. Does it not work that way?

Second, for the same reason you wouldnt make a starter with dextrose, since you want to prime and reproduce the yeast most adept for fermenting sugars like it will be working in the wort, wouldnt the same logic go that the starter for a high gravity beer, regardless of the number of vials used, should be in a relatively high gravity environment so the yeast more adept and functional at higher gravity get reproduced?

 

[MalFet]

One, while the yeast is very good at detecting its own population levels, it should also have a very good ability at detecting its environmental conditions. If you have less fermentables in an environment then the yeast wont reproduce to the same degree as if there were more fermentables. Does it not work that way?

As far as my understanding goes, it does work that way. But, it's a trade-off. High gravity wort will stress yeast, low gravity wort will under feed them. I'm not sure where the 1.040 number came from in particular, though that certainly has been the environment that beer yeast has been bred to enjoy. I think it's possible, even likely, that you'd end up with more growth in 1L of 1.080 wort than in 1L of 1.040 wort, but the protocol would tell you to make 2L of 1.040. Just as much sugar, easier living.

Second, for the same reason you wouldnt make a starter with dextrose, since you want to prime and reproduce the yeast most adept for fermenting sugars like it will be working in the wort, wouldnt the same logic go that the starter for a high gravity beer, regardless of the number of vials used, should be in a relatively high gravity environment so the yeast more adept and functional at higher gravity get reproduced?

No, at least that's not the research I have seen. With dextrose, the problem is that the yeast end up not properly manufacturing the enzymes necessary to break down the more complex forms of sugar. I don't know of any particular mechanisms that allow yeast to "prepare for" higher gravity worts in equivalent ways.

 

[deputyandy]

Since this starter is going to large, I'm thinking of decanting the spent wort. When's the best time to cold crash a starter? I'm planning on making the starter tonight, brewing Saturday or Sunday.

 

[MalFet]

Since this starter is going to large, I'm thinking of decanting the spent wort. When's the best time to cold crash a starter? I'm planning on making the starter tonight, brewing Saturday or Sunday.

My rule of thumb is two days on the plate and two days in the fridge. In a pinch, 18h and 18h would work.