Stir during lautering - mash in bag/cooler

[McKnuckle]

In traditional bag-less brewing, we stir the mash at the end, vorlauf to set the grain bed, then lauter without disturbing it further.

Mashing in a bag makes a vorlauf unnecessary. And so I wonder, for those of you who mash in a bag inside a cooler, have you tried stirring the grain while lautering? I would think it might result in better rinsing, especially for a no-sparge full-volume mash. Perhaps even a slight whirlpool effect could be achieved, drawing sugar down towards the bottom pickup tube.

Does anyone incorporate this technique?

 

[farmersteve]

I use a sous vide heater both in a pot and cooler. I think the circulation helps quite a bit with efficiency

 

[McKnuckle]

I'm fascinated that at least 50 thread viewers can't speak of doing this. I guess I'll have to try and report back.

 

[farmersteve]

We need Brulosophy to do an experiment

 

[McKnuckle]

I don't think there would be any flavor or quality difference, just a potential efficiency bump. Like I said initially, seems that this would be easy to do since the bag provides a filter, and the stirring should dislodge additional sugar. I Googled before posting and couldn't find any mention of it.

 

[wilserbrewer]

I don't understand what benefits there could be. All the sugar is in solution at the end of the mash, not stuck to the grain whereby stirring will shake it loose.

The only thing I see happening is perhaps more trub finding its way through the bag from stirring.

Are you looking for an efficiency gain? Done correctly BIAB efficiency should be good and not need any steps such as this.

I'm confused on the "why"?

Certainly a good idea to stir well before lautering, but I can't understand a reason to stir during lautering.

 

[doug293cz]

I don't understand what benefits there could be. All the sugar is in solution at the end of the mash, not stuck to the grain whereby stirring will shake it loose.

The only thing I see happening is perhaps more trub finding its way through the bag from stirring.

Are you looking for an efficiency gain? Done correctly BIAB efficiency should be good and not need any steps such as this.

I'm confused on the "why"?

Certainly a good idea to stir well before lautering, but I can't understand a reason to stir during lautering.

Wilser's got it right. All you need to do with stirring is get the wort concentration uniform between the initial mash wort and the sparge water. After that, no benefit. (Unless your mash time was too short and you sitll have significant conversion going on during the sparge, in which case you have other problems.)

Brew on

 

[McKnuckle]

I'm talking strictly about lauter efficiency, not conversion. But okay, I see the reasons for skepticism. Also, no likely harm or ill effects so it's worth a shot.

 

[doug293cz]

I'm talking strictly about lauter efficiency, not conversion. But okay, I see the reasons for skepticism. Also, no likely harm or ill effects so it's worth a shot.

You're correct that it won't hurt anything, but do you have a theory about how stirring might increase lauter efficiency? If the wort is homogeneous (why you stir before lautering), then lauter efficiency is determined only by how much wort you started with in the mash, and how much is left behind at the end of lautering (for a no sparge process.)

Lauter Efficiency = (Starting Wort Vol - Absorbed Wort Vol) / Starting Wort Vol​

Brew on

 

[McKnuckle]

I would not position this as a theory - that's far too advanced. It's more of a gut feeling. I often think of lautering like rinsing off in the shower or bathtub after soaping up. The soap is the sugar. Different types of rinsing or dunking are variably effective in getting all the soap off.

Think of sitting in the bathtub, stirring the soapy water around, waiting for it to settle, then draining. Compare that to sitting in the bathtub, stirring the soapy water around, then draining while continuing to stir. It might prevent soap from sticking to your skin during the drain. It might create a whirlpool that pulls a little more soap off your body.

Okay, enough of that analogy, but hopefully it gives some insight to my potentially flawed thinking.

 

[doug293cz]

I would not position this as a theory - that's far too advanced. It's more of a gut feeling. I often think of lautering like rinsing off in the shower or bathtub after soaping up. The soap is the sugar. Different types of rinsing or dunking are variably effective in getting all the soap off.

Think of sitting in the bathtub, stirring the soapy water around, waiting for it to settle, then draining. Compare that to sitting in the bathtub, stirring the soapy water around, then draining while continuing to stir. It might prevent soap from sticking to your skin during the drain. It might create a whirlpool that pulls a little more soap off your body.

Okay, enough of that analogy, but hopefully it gives some insight to my potentially flawed thinking.

Okay, I think I understand your thinking better now. I think the flaw is that in true solutions, as opposed to particulate suspensions, settling does not occur. In the mash all of the sugar is in solution from the moment it's created, and the solution is never saturated, so no sugar precipitates out. So, stirring during lautering is not going to keep any additional sugar in suspension, since none of it is ever in suspension. Once the wort is homogenized by initial stirring, it stays that way. The wort that ends up clinging to the grits after lautering has the same SG as the wort you collected in the BK.

Brew on

 

[madscientist451]

I'm a bag in the cooler brewer, I usually only stir at the beginning when adding the grains and later, after the batch sparge water is added. I do a manual re-circulation, partly to clear up the wort but also I seem to be more likely to hit my numbers when I re-circulate. Maybe next time I'll stir before re-circulating and see what happens.

 

[wilserbrewer]

Sugar in solution does not stick to anything or settle.

Think of the same bathtub example but with several drops of food coloring mixed well in the water, the dye is evenly distributed in the water and will drain the same regardless of stirring or not as it is already thoroughly mixed in solution.

 

[farmersteve]

Then why do people that recirculate say they get better extraction?

 

[doug293cz]

Then why do people that recirculate say they get better extraction?

Recirculation speeds up conversion, so improves conversion efficiency in cases where the mash time is not sufficient for complete conversion. Mash recirculation has no effect on lauter efficiency.

Vorlaufing can improve lauter efficiency in MLT's with false bottoms. This is because the volume under the FB does not participate fully in the mash. Unless the mash is recirculated, sugar only gets into the water under the FB by diffusion. So, the wort under the FB is usually lower SG than the wort up in the grain bed. Stirring the grain bed is not effective at homogenizing the wort above and below the FB. Vorlaufing will take the low SG wort and put it into the grain bed, which lowers the SG of the wort in the grain bed slightly. The lower the SG of the wort in the grain bed, the less sugar is retained in the grain bed due to absorption.

Brew on

 

[mongoose33]

I did something similar to a bag--my mash tun has a torpedo screen, and in a moment of lucidity it dawned on me I could tie a hop sock around it and speed up the process.

Analogous in some respects to using a bag, I think.

Seems to me that stirring would disturb the grain bed and provide the opportunity for small particles to make it through the bag. I'm not sure why that would be desirable, but maybe it would be depending on your goals.

I also wonder if stirring, by freeing small particles that would have been stuck in the grain bed, they'd be more likely to clog the bag (those too large to go through, that is).