Mash times

[tommy24a]

Ok, put together my 20 gal spike trio equipment and just simulated a run thru with just water to get familer with the process. Was following a Beersmith recipe for mash tens and times. Also had the spike process manual out to help. In spikes process manual they say mash times should be around 30 to 45 minutes because of the spikes constantly recirculation mash process. But my Beersmith recipe calls for 75 mins to hold the mash. How do I tell when the conversion of the starch are complete?

 

[RM-MN]

There are two ways to tell if conversion is complete. Removing a little grain from the mash and dropping iodine on it will tell you if there is starch left as the iodine will turn dark blue in the presence of starch. Most of the time you will find that there is still starch unless you mill your grains to near flour.

The second way is to use a refractometer and take multiple samples. If the reading is still going up, conversion is not complete.

Now think about conversion. Do you need complete conversion? Probably not. You need sufficient conversion to make the OG of the wort fit into the expectation of the recipe. If the recipe is written for 70% brewhouse efficiency and you manage 90% your beer will not be like the recipe.

 

[tommy24a]

There are two ways to tell if conversion is complete. Removing a little grain from the mash and dropping iodine on it will tell you if there is starch left as the iodine will turn dark blue in the presence of starch. Most of the time you will find that there is still starch unless you mill your grains to near flour.

The second way is to use a refractometer and take multiple samples. If the reading is still going up, conversion is not complete.
Very interesting and also very helpful! Thanks for your help! Happy Holidays!

Now think about conversion. Do you need complete conversion? Probably not. You need sufficient conversion to make the OG of the wort fit into the expectation of the recipe. If the recipe is written for 70% brewhouse efficiency and you manage 90% your beer will not be like the recipe.

 

[tommy24a]

Thanks!

 

[McKnuckle]

Mash recirculation is not a magic pill for extremely efficient results. I think Spike is being a bit misleading in that literature, but even if they are right about their product's performance, I would not follow their advice.

Sorry that this gets a little verbose, but:

Conversion is literally converting starches to sugars - that's true. But there's more to it than that. Are you familiar with beta and alpha amylase, the enzymes that do the conversion? They work at different temperatures, take different amounts of time to work, and do slightly different things.

Simply put, alpha chops the starches randomly into long chain sugars that are not always fermentable. Beta snips these into short chains that are easily fermentable. Most of the attenuation by yeast is a result of fermenting the sugars that beta amylase created.

Think of alpha as cutting off branches from a tree, and beta snipping the buds.

Alpha amylase works quickly and likes it hot. Beta is slower and prefers it a bit cooler (152º is often stated as the midway point).

So how does mash time come into play? If you mash for 30 minutes at 150ºF, which is in the beta range, that's not enough time for it to complete its job. You see 90 minute mashes routinely for these lower temps for a reason.

A hotter mash, say 156ºF, with more alpha activity happens fast, it's true. But then you have mostly long chain, less fermentable sugars. If you left that mash to sit for longer, you'd see some beta activity chopping up the (already converted!) longer chain sugars into shorter, fermentable ones.

Then besides conversion, you have extraction of flavor and other goodness from your precious malt. I'd just follow recipes and mash for the typical 60-90 minute duration.

 

[tommy24a]

Mash recirculation is not a magic pill for extremely efficient results. I think Spike is being a bit misleading in that literature, but even if they are right about their product's performance, I would not follow their advice.

Sorry that this gets a little verbose, but:

Conversion is literally converting starches to sugars - that's true. But there's more to it than that. Are you familiar with beta and alpha amylase, the enzymes that do the conversion? They work at different temperatures, take different amounts of time to work, and do slightly different things.

Simply put, alpha chops the starches randomly into long chain sugars that are not always fermentable. Beta snips these into short chains that are easily fermentable. Most of the attenuation by yeast is a result of fermenting the sugars that beta amylase created.

Think of alpha as cutting off branches from a tree, and beta snipping the buds.

Alpha amylase works quickly and likes it hot. Beta is slower and prefers it a bit cooler (152º is often stated as the midway point).

So how does mash time come into play? If you mash for 30 minutes at 150ºF, which is in the beta range, that's not enough time for it to complete its job. You see 90 minute mashes routinely for these lower temps for a reason.

A hotter mash, say 156ºF, with more alpha activity happens fast, it's true. But then you have mostly long chain, less fermentable sugars. If you left that mash to sit for longer, you'd see some beta activity chopping up the (already converted!) longer chain sugars into shorter, fermentable ones.

Then besides conversion, you have extraction of flavor and other goodness from your precious malt. I'd just follow recipes and mash for the typical 60-90 minute duration.

Got ya! Yea I was kind of leaning towards the recipe advice to be honest. Great explanation for sure. Thank for taking the time to explain how this all works. Thanks again!

 

[kevin58]

Nice explanation @McKnuckle. I tried explaining it on my Youtube channel once and gave up and didn't post that episode.

 

[Vale71]

Get yourself some iodine tincture and start checking your mash regularly to get a feel for when conversion is complete. You have to check only the liquid part as solids will always react with iodine and that's misleading.

 

[tommy24a]

Get yourself some iodine tincture and start checking your mash regularly to get a feel for when conversion is complete. You have to check only the liquid part as solids will always react with iodine and that's misleading.

I shall do that, thanks!

 

[doug293cz]

Get yourself some iodine tincture and start checking your mash regularly to get a feel for when conversion is complete. You have to check only the liquid part as solids will always react with iodine and that's misleading.

If the solids give a positive starch response with iodine, that means the solids (grits) still contain starch. If this is the case, then conversion is not complete.

Brew on

 

[tommy24a]

If the solids give a positive starch response with iodine, that means the solids (grits) still contain starch. If this is the case, then conversion is not complete.

Brew on

So check the solids or liquid or both?

 

[VikeMan]

Just a word about iodine testes and "complete" conversion. An iodine test may indicate complete conversion, but that doesn't tell you much about the fermentability of the wort. Longer mashes yield more fermentable worts. i.e. the OG may not still be changing, but the potential for attenuation is.

 

[Vale71]

Just a word about iodine testes and "complete" conversion. An iodine test may indicate complete conversion, but that doesn't tell you much about the fermentability of the wort. Longer mashes yield more fermentable worts. i.e. the OG may not still be changing, but the potential for attenuation is.

That is correct. The iodine test is a go/no-go test. As long as you have a reaction it's not safe to mash out. Once you no longer have a reaction you decide whether to mash out or wait for a fixed amount of time in any case, for example because you aim for a very high attenuation.

 

[Vale71]

If the solids give a positive starch response with iodine, that means the solids (grits) still contain starch. If this is the case, then conversion is not complete.

Brew on

Well then I guess all breweries across the world must be doing it wrong because that's how they do it...

There will always be some starch in the grist just as there will always be some starch in the wort and in the finished beer as well. There are quality threshold that must not be exceeded and very large breweries do test for that but since they're rather time-consuming and expensive analysis smaller breweries are just happy with the visual iodine test performed at the brewhouse.

 

[Vale71]

So check the solids or liquid or both?

Just the liquid.

 

[Senormac]

Ok, put together my 20 gal spike trio equipment

How bout a picture tommy. I love seeing op's brew rigs as I'm in process of building one of my own. A Spike too !

 

[tommy24a]

How bout a picture tommy. I love seeing op's brew rigs as I'm in process of building one of my own. A Spike too !

 

[Senormac]

Very nice. I see you have gone electric as opposed to propane which makes sense as your brew station is indoors. I also like the sink. Running hot water is a big bonus. Thx for the photos. I'm sure it will serve you well over many years.

 

[doug293cz]

The iodine test is not really a very good way to determine if your mash is done, or "done enough" for you. It is relatively straight forward to calculate the maximum weight of extract (sugar plus proteins, and other dissolved matter) that can be created in your mash. It's also not difficult to determine the weight of extract actually created in your mash. At 100% conversion, these two values are equal. In other cases, the percent conversion completed (conversion efficiency) is determined by this formula:

Percent conversion = 100% * Weight of extract created in mash / Max potential weight of extract​

or, Fraction converted = Extractactual / Extractmax​

​

To calculate the potential weight of extract, start with the ppg of the grain bill (the weighted average of the ppg's of each of the grain bill components), and convert that to percent of the grain that can be converted to extract. Since potentials are given based on dry grain weight, and most grain contains about 4% moisture, we have throw in a multiplier of 0.96 to correct for the fact that we are weighing moisture containing grain. If 100% of the grain could be converted then it would have a potential of 46.173 ppg (this is the ppg of sucrose which is 100% sugar.) The formula for potential extract weight is:

Extractmax = Grain weight * 0.96 * Grain bill ppg / 46.173​

​

This can be converted to the maximum possible wort SG in the mash, first in °Plato, and then SG. °Plato is just the weight percent of extract in the wort, which is equal to the weight of extract / (weight of extract + weight of strike water). Water has a density of 8.33 lb/gal at 68°F (20°C). The formula for SG in °P becomes:

°Pmax = 100° * Max potential extract [lb] / (Max potential extract [lb] + Strike volume [gal] * 8.33 lb/gal)​

​

The formula to convert °Pmax into SGmax is:

SGmax = 1 + °Pmax / (258.6 - (°Pmax / 258.2) * 227.1)​

​

We can now get an approximate % conversion using the following formula:

% Conversion = 100% * (SGactual - 1) / (SGmax - 1)​

​

The above formulas can all be put into a simple spreadsheet, so you don't have to do any calculations by hand.

​

Prior to taking the SG measurement of the wort in the mash, you must make sure the wort is homogenized throughout the entire volume of the mash vessel. For simple BIAB, stirring the mash aggressively prior to sampling is adequate. With a false bottom, continuous recirculation, or vorlaufing (2 - 3X the volume under the FB) followed by a stir, will give you sufficient homogenization prior to sampling. Systems with a malt pipe have special challenges when it comes to homogenizing the wort, but we won't take that up here.

-----------------------------------------------------------------------------------------------------------------

For the more pedantic geeks among us, the more rigorous calculations for % conversion follow.

Measure the SGactual of the wort in the mash (after homogenizing.) Then convert SGactual to °Pactual using the following formula:

°Pactual = (1111.14 * SGactual) - (630.272 * SGactual^2) + (135.9975 * SGactual^3) - 616.868​

​

Now calculate Extractactual from °Pactual as follows:

°Pactual / 100° = Extractactual / (Extractactual + Strike Water Weight)​

°Pactual / 100° * (Extractactual + Strike Water Weight) = Extractactual ​

Extractactual = (°Pactual / 100°) * Extractactual + (°Pactual / 100°) * Strike Water Weight​

Extractactual - Extractactual * °Pactual / 100° = (°Pactual / 100°) * Strike Water Weight​

Extractactual * (1 - °Pactual / 100°) = (°Pactual / 100°) * Strike Water Weight​

​

Extractactual = (°Pactual / 100°) * Strike Water Weight / (1 - °Pactual / 100°)​

​

Since we calculated Extractmax above, we can now calculate the percent conversion as:

% Conversion = 100% * Extractactual / Extractmax​

​

We can manipulate the equations a bit more and come up with another formula for % conversion that depends only on Plato measurements. This formula is convenient if you normally measure SG in Plato.

% Conversion = 100% * (°Pactual / 100°) * Strike Water Weight * (1 - °Pmax / 100) / ((°Pmax / 100) * Strike Water Weight * (1 - °Pactual / 100°))​

​

% Conversion = 100% * °Pactual * (100 - °Pmax) / (°Pmax * (100 - °Pactual ))​

​

Brew on

 

[tommy24a]

Very nice. I see you have gone electric as opposed to propane which makes sense as your brew station is indoors. I also like the sink. Running hot water is a big bonus. Thx for the photos. I'm sure it will serve you well over many years.

Yes all electric...yes had to come up with a few solutions for a sink and drain. Have not brewed at all yet on this system. Just ran thru a simulation yesterday of the brewing process with just water to get a hang of the ins and outs. Noted the take aways and things we can improve when we go live.

 

[jdudek]

Well then I guess all breweries across the world must be doing it wrong because that's how they do it...

commercial breweries use iodine tests to tell if their conversion is complete...?

 

[Vale71]

commercial breweries use iodine tests to tell if their conversion is complete...?

Indeed they do. In the brewhouse it's a simple visual test just like we do. In the lab it's a time consuming procedure involving adsorption spectrophotometry but the reagent is still iodine (a 0.2N solution if I recall correctly).

 

[ESBrewer]

I would simply start with standard ~one hour mash (recirculated). If this leads to a higher than expected FG you can start adjusting mash time and maybe even mash temperature in your future brews. The color seen in the simple iodine test does correlate with the progress of the mash but it is actually not very quantitative in terms of FG as the iodine does not bind that well to short chain dextrins that are intermediary between starch and fermentable sugars. So it actually tells you that there are no more big trees or branches in the forest (of starch) but it does not guarantee that everything has been ground to sawdust (by beta-amylase) that can be consumed by the yeast. In addition, it ain't always easy to measure the exact color by eye.

 

[Vale71]

...it does not guarantee that everything has been ground to sawdust (by beta-amylase) that can be consumed by the yeast.

So you're saying that one should always aim for 100% fermentability? How would you achieve that without synthetic enzyme additions?

 

[ESBrewer]

No, I did not say that. I mean that you won't see the exact level of fermentability by doing the simple iodine test (the ratio between short chain dextrin and fermentable sugar (maltose etc.) and thus it won't reveal the FG of the beer. I'm not saying that it is useless to test with iodine. It could be useful, especially if there is any chance that the mash is not working properly.

 

[Vale71]

No, I did not say that. I mean that you won't see the exact level of fermentability by doing the simple iodine test (the ratio between short chain dextrin and fermentable sugar (maltose etc.) and thus it won't reveal the FG of the beer. I'm not saying that it is useless to test with iodine. It could be useful, especially if there is any chance that the mash is not working properly.

If you say that everything needs to be ground to sawdust that can be consumed by the yeast then that is exactly what you were saying. Also by saying that the iodine test does not measure fermentability you seem to be implying that there is a better test that does measure that. Unfortunately that is not the case as there is no quick test that can be performed prior to mash-out so your observation, although technically correct, seems quite pointless.

 

[ESBrewer]

I'm using a metaphor - if the starch macromolecule is a tree then simple sugar molecules form sawdust. Not talking about grinding the malt at all and especially not advicing anyone to grind malts to dust.

 

[Vale71]

That part was clear. What was not clear was why you were critizing the iodine test for not being able to detect 100% fermentability which is a condition that will never occur in beer brewing or alternately for not being able to predict FG during mashing which is something that cannot be tested for in the brewhouse in any case.

 

[VikeMan]

commercial breweries use iodine tests to tell if their conversion is complete...?

Some probably do. I've performed, participated in, and witnessed quite a few commercial mashes in several breweries and have not seen any iodine tests. But I could certainly imagine it being done when a new mash process or piece of equipment is incorporated, as a test to make sure some parameter hasn't been inadvertently thrown out of whack. And maybe some breweries do them all the time, as insurance.

 

[Vale71]

What size breweries are we talking about?

Very large operations might not do that at all but that's because they have done extensive testing on every lot of malt they receive (most likely malted to proprietary specifications) so they already know they will achieve full conversion by mashout. They will certainly test the final product/wort in the lab but that's not something you would have seen if you were just there on brew day.

Smaller breweries on the other hand (say bre-pub sized) can be even lazier than the laziest homebrewer and might not be the best choice of role model...

 

[VikeMan]

What size breweries are we talking about?

Batch sizes were between 15 gallons and 15 barrels.

 

[oakbarn]

If the solids give a positive starch response with iodine, that means the solids (grits) still contain starch. If this is the case, then conversion is not complete.

Brew on

I agree with only checking the liquid. Even after a 90 min mash, a grain will turn black with iodine. I used to test but no longer do as it can be misleading. I simply use Temperature and Time (and I do use a modified HERMS, for the Mash. I cut one Mash short using the Iodine Test and I obviously misread the results. Most of the time, we mash for 90 minutes.

 

[Vale71]

Batch sizes were between 15 gallons and 15 barrels.

Ok so probably just lazy then...

 

[Vale71]

I agree with only checking the liquid. Even after a 90 min mash, a grain will turn black with iodine.

I'm not hundred percent sure but I think iodine will react strongly with non-soluble, non convertible polysaccharides that will stay behind in the spent grains so that basically a iodine test with solid particles will always show positive no matter how long you wait.

 

[RM-MN]

The grain particles will only turn blue/black if there is starch left which then implies incomplete conversion. I have tested this with my own milled grains and will get no color change with the iodine. To achieve this the particles of grain must be small, much smaller than can be used in a conventional mash tun without a filter bag.

 

[Vale71]

Those very small particles are just made of fiber (husk material) which is why they don't react. Endosperm fragments will always react with iodine which does not imply incomplete conversion.

 

[RM-MN]

So check the solids or liquid or both?

Do you want to check for complete conversion (not easily achieved for most people) or do you want to check to see if you have unconverted starch in the wort? Your original question was, "How do I tell when the conversion of the starch are complete?" That doesn't matter in the context of making beer from a recipe. You want sufficient conversion, enough to get the OG of the recipe which was likely written with about 70% brewhouse efficiency. That doesn't require complete conversion, it requires that you get enough so that when you extract the sugars from the grain by draining the mash tun (probably followed by a sparge to get some more sugars) you hit the desired OG.

 

[RM-MN]

Those very small particles are just made of fiber (husk material) which is why they don't react. Endosperm fragments will always react with iodine which does not imply incomplete conversion.

Nope. If that were the case I would always get a color change from the iodine being applied to the grist. Since I don't, that can't be the case.

 

[tommy24a]

Do you want to check for complete conversion (not easily achieved for most people) or do you want to check to see if you have unconverted starch in the wort? Your original question was, "How do I tell when the conversion of the starch are complete?" That doesn't matter in the context of making beer from a recipe. You want sufficient conversion, enough to get the OG of the recipe which was likely written with about 70% brewhouse efficiency. That doesn't require complete conversion, it requires that you get enough so that when you extract the sugars from the grain by draining the mash tun (probably followed by a sparge to get some more sugars) you hit the desired OG.

You are correct, my original question was how do I tell if I have let it mash enough time. My recipe calls for 75mins mash time but my equipment process guide says 30 to 45 mins is sufficient due to the efficiency of the MT.

 

[RM-MN]

You are correct, my original question was how do I tell if I have let it mash enough time. My recipe calls for 75mins mash time but my equipment process guide says 30 to 45 mins is sufficient due to the efficiency of the MT.

You won't really know until you have done a few batches and checked how close your OG comes to the recipe's OG. Most people achieve this with a "standard" 60 minute mash. If your grains are milled more coarsely a 75 to 90 minute mash may be needed. If the grains are milled really fine, less time is fine. Do not go less than 30 minutes as the flavor takes longer to extract than does conversion with finely milled grains.