Grist thickness as relating to tun deadspace in herms system

[farmskis]

Hello all, just getting back into brewing after about a 6 yr hiatus.

Reading through Palmers How to Brew Book I was looking through the Mash science section. Towards the end it states that thin mashes have the enzymes less concentrated and this could slow conversion and leads to quicker denaturing but can lead to more fermentable wort because the enzymes are not inhibited by the high concentration of sugars. Opposite for thick mash.

My question comes with determining the grist ratio. Usually I had always counted water under the false bottom and in the germs coil as dead space and I would add this amount to the calculated grist ratio I was wanting. Is this technique wrong? In the description above from the book it would seem that if you are circulating the wort that the enzymes would be less concentrated due to the extra water added to account for the headspace and that I should really not add the dead space amount on to the calculated grist ratio amount.

Maybe I am just looking at this wrong.

Any comments?

 

[day_trippr]

I run a 3v2p herms doing 10 gallon batches and consider the volume under my FB to be "recoverable", so my strike liquor volume calculation does not split that volume out. For a typical double IPA with 28 pounds of grain the strike volume is typically ~9 gallons, just under 1.3 quarts per pound and in the middle of the recommended ratio range...

Cheers!

 

[farmskis]

I think I am reading you correct. So as long as the wort under the FB is recoverable to the boil kettle we should count it as part of the grain to water ratio?
From what I am understanding we basically are shooting for a certain concentration of enzymes in our mash water? So weather it is under a fb or in the grist itself it still is mixing with the enzymes and creating the proper concentration in the mash.

 

[day_trippr]

Yup, that's been my understanding forever

Cheers!

 

[Bobby_M]

I have never seen any issues with conversion even no sparge water ratios.

 

[doug293cz]

Hello all, just getting back into brewing after about a 6 yr hiatus.

Reading through Palmers How to Brew Book I was looking through the Mash science section. Towards the end it states that thin mashes have the enzymes less concentrated and this could slow conversion and leads to quicker denaturing but can lead to more fermentable wort because the enzymes are not inhibited by the high concentration of sugars. Opposite for thick mash.

My question comes with determining the grist ratio. Usually I had always counted water under the false bottom and in the germs coil as dead space and I would add this amount to the calculated grist ratio I was wanting. Is this technique wrong? In the description above from the book it would seem that if you are circulating the wort that the enzymes would be less concentrated due to the extra water added to account for the headspace and that I should really not add the dead space amount on to the calculated grist ratio amount.

Maybe I am just looking at this wrong.

Any comments?

Braukaiser has found that thinner mashes convert faster than thicker mashes, which can lead to better conversion efficiency in time limited mashes (where at a slower conversion rate, conversion may not complete in the allotted time.) You can compensate for the lower conversion rate of thicker mashes by mashing longer to get to 100% conversion. You can also crush finer to speed up the conversion rate, if that doesn't cause problems in your system.

There is no "optimal" mash thickness. There is a practical upper limit to mash thickness (lower limit to water to grain ratio) which occurs when you can no longer adequately mix the grain with the water (too hard to stir) and/or when there is not enough water to completely cover the grain bed.

What you want to do is determine the practical min water:grain ratio for your system, then multiply that by your grain bill weight, and finally add all of the volume under your false bottom and in the recirculation plumbing. The result is your minimum strike water volume. You can use more than this minimum strike volume if it is convenient for you in any way.

If you are fly sparging, then using the minimum strike water volume will maximize your lauter efficiency, since you will be able to sparge with more water before reaching your pre-boil volume target. If batch sparging, then you maximize lauter efficiency by having equal volumes for the initial run-off, and all sparge run-offs.

You maximize mash efficiency by maximizing both conversion efficiency and lauter efficiency, since mash efficiency = conversion efficiency * lauter efficiency.

Brew on

 

[Bramling Cross]

I have never seen any issues with conversion even no sparge water ratios.

My practical experience agrees with this. Over thirty years of brewing my mashes have slowly become looser and looser and looser. Especially now that I've returned to fly sparging over the past five years, I have a strong preference for minimizing my sparge volume via a loose strike at 148F followed by a cool, large infusion step to 158F. The beers seem better that way and my efficiency doesn't seem to suffer due to the smaller sparge volume--personally, I think efficiency is mostly in the crush, the mechanics of the lauter, and water chemistry (ranked in descending order). My experience doing no sparge UK ales on my old batch sparge rig encouraged me to go in this direction.

Frankly, I don't account for the volume occupied by my recirculating rig: 1) it's negligible compared to the larger mash volume; 2) that volume should be mostly recoverable provided you have a mechanically sound brewery (that is, it's able to lauter your mash without a sizeable volume of sweet wort being rendered unavailable to the kettle); 3) assuming you don't have underlying water chemistry or crush issues, it's a rounding error at best.

Frankly, I think Palmer's book causes more problems than it solves these days. It was great when it was published, but it has grown long in the tooth.

 

[farmskis]

I have never seen any issues with conversion even no sparge water ratios.

If my mash tun can hold the entire amount of mash and sparge water is there a benefit to sparging if you notice no conversion efficiency effect? I will recirculate during the mash. Or possibly at the very least use very little sparge water to give a little rinse.

 

[Bobby_M]

If my mash tun can hold the entire amount of mash and sparge water is there a benefit to sparging if you notice no conversion efficiency effect? I will recirculate during the mash. Or possibly at the very least use very little sparge water to give a little rinse.

There is no conversion efficiency effect, but there will be a lauter and brewhouse efficiency drop without a sparge. The more of the volume derived from the sparge, the higher the lauter efficiency you'll get. However, that's not a goal many people are after. A high efficiency sparge takes extra time, water calculations, and the possibility of oversparging. I take the lower efficiency by full volume mashing and add a little more grain.

 

[brewbama]

I take the same approach as Bobby. I also have a HERMS but haven’t sparged in years. I simply calc a bit more grain and do a full volume mash much like BIABers do. However, I am brewing 3.5 and 1.5 gal batches otherwise I’d have to scale up the MLT to hold the full volume. I haven’t seen any issues with conversion

 

[farmskis]

There is no conversion efficiency effect, but there will be a lauter and brewhouse efficiency drop without a sparge. The more of the volume derived from the sparge, the higher the lauter efficiency you'll get. However, that's not a goal many people are after. A high efficiency sparge takes extra time, water calculations, and the possibility of oversparging. I take the lower efficiency by full volume mashing and add a little more grain.

I take the same approach as Bobby. I also have a HERMS but haven’t sparged in years. I simply calc a bit more grain and do a full volume mash much like BIABers do. However, I am brewing 3.5 and 1.5 gal batches otherwise I’d have to scale up the MLT to hold the full volume. I haven’t seen any issues with conversion

Just curious on what is your brew house efficiency you plan for? What was the loss in brewhouse efficiency when you started going to a no sparge, if you have a comparison that is?

 

[scrap iron]

I have been doing no sparge for about 3 years now and I plan on 65% efficiency.
I just add a pound or two of malt extra than when I did fly sparge. You have to account for the grain absorption and boil off rate to get your final volume. I figure 1/2 quart per pound of grain. I use a false bottom in the mash tun without a bag.

 

[Cheshire Cat]

I use a 3 to 1 ratio of grain to water for the mash. My AIO has a dead space of 7 litre. So the mash volume for 5kg of grain is 22 litres. The sparge water is calculated as that needed for the pre boil volume. I do a fly sparge with a jug. I get 75% BHE for all but wheat beers.

 

[Bobby_M]

No sparge, figure 75% into the boil kettle. Fly sparge would be about 85%. Brewhouse efficiency is more fluid and factors in losses post boil dependent on how much trub volume you leave behind.

 

[doug293cz]

Just curious on what is your brew house efficiency you plan for? What was the loss in brewhouse efficiency when you started going to a no sparge, if you have a comparison that is?

Here's a chart that shows how lauter efficiency varies with number of optimal batch sparge steps for two different grain absorption rates - 0.12 gal/lb (typical for a traditional MLT) and 0.06 gal/lb (achievable with BIAB and aggressive bag squeezing.) The chart also shows how lauter efficiency drops off as the grain weight to pre-boil volume ratio increases (as beers get "bigger.") One take-away is that is single batch sparge gives you about 8 - 8.5 percentage points increased lauter efficiency, for the same grain absorption rate. A good fly sparge can give you slightly better lauter efficiency than a triple batch sparge.

As @Bobby_M noted, more goes into brewhouse efficiency than lauter efficiency, which is the only component of brewhouse efficiency affected by the sparge process.

Mash Efficiency = Conversion Efficiency * Lauter Efficiency​

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Brewhouse Efficiency = Mash Efficiency * Fermenter Volume / Post-Boil Volume​

Brewhouse Efficiency = Conversion Efficiency * Lauter Efficiency * Fermenter Volume / Post-Boil Volume​

The difference between mash efficiency and brewhouse efficiency is totally determined by how much wort/trub you leave behind in the BK and plumbing (and any you spill) when transferring to the fermenter.

Brew on