Cold Steep Extract Efficiency

[HBearBrew]

I have always wanted to try the cold steep method for dark and specialty while brewing a stout, but the lack of literature on extract efficiency with cold steep somehow always stopped me. I was especially interested as cold steeping would enable me to lower the amount of grain in my main grist, which would ease my mash and boost my efficiency. I wanted to cold steep because all the well-researched advantages in terms of flavors being less astringent, but at the same time also make sure to extract enough sugars out it it so I don't just get color and flavors, and none of the unfermentable sugars needed to give body to my stout.

While everyone agrees cold steep is less efficient, I have struggled to find any agreement or data out there. Advice go from increase by 10% to increase 3 fold in order to reach similar extraction with simply mashing my dark with the rest of the grains. So I recorded my data and I am sharing it for whoever is interested.

I had planned on using 0.4kg chocolate, 0.3kg roasted barley and 0.3kg special B. Not knowing where to start I decided to double these quantities. So 0.8kg chocolate, 0.6kg roasted barley and 0.6kg special B, with a mash thickness of 5 L/kg (2kgs total in 10L water) - that is, 2.6 quarts of water per pound of grains.

I went for a 24h room temperature mash, BIAB no sparge - so no need to discuss how my sparge could have or not affect the results I collected 9 Liters at 1.035.

Using Palmer's book, I calculated that the maximum extraction for my cold steep would have been 62.6 [using PKL, (284x(0.8/9)+300x(0.6/9)+261x(0.6/9)]. I have therefore obtained a cold steep efficiency of 56%.

This means that when planning to use cold steep with dark grains when extracting sugars matter, at a wort volume to grain ratio of 5L/kg (2.6qt/lbs), the expected efficiency is closer to 50%. In other words, using 1.5x the amount compared to the amount you planned for hot mashing would bring you in the same range. A mash at any other water to grist ratio would yield a different result of course, that's why I am making sure to indicate the ratio I used.

I then proceeded on topping this dark wort with water to my desired mash volume and went for an overnight mash with the rest of the grains.

To the million dollars question -- how does the final stout taste -- I'll post the result here in few weeks, and the full recipe if it turned out good

 

[khannon]

I have done cold steeping in the past.. just for dark grains.. Black patent, super roasted stuff etc.. you are not really getting sugars from them, mainly color and to a degree taste.

I tend to go 1.5 times what I would otherwise do, but it is usually a small percent of the grain bill

I liked it, and would tend to liken to cold brew coffee vs traditional iced coffee. A bit less astringent and a little bit "smoother".

Just my experience.

 

[kmarkstevens]

You should check out this thread: Low Enzymatic/Cold Mash/Low alcohol beer

Although the focus was on the base grains more than specialty malts.

 

[BrewnWKopperKat]

I have struggled to find any agreement or data out there.

Did you see this (from Nov 2010) Testing fermentability of crystal malt ? There is also a summary here Fermentability of Crystal Malt. I found both by following references in the book Brewing Engineering.

 

[HBearBrew]

Did you see this (from Nov 2010) Testing fermentability of crystal malt ? There is also a summary here Fermentability of Crystal Malt. I found both by following references in the book Brewing Engineering.

Very interesting! He wrote
"If you really want to fine tune your recipes you can use the difference in fermentability to adjust your final gravity calculation. These would be:
-6% for C10
-20% for C40
-26% for C120"

I used Special B, chocolate and roasted barley so all C120+ and got a similar result, but around -20% only.

This could make the case that the PPG of dark grains extracted with cold steep for 24h at room temp is slightly more efficient than a hot mash of 155F for 30min?

I am not necessarily advocating to cold steep dark grains over mashing, I like the convenience of just throwing them in with the rest of the grains during my mash. I only tried this because I wanted to do an overnight mash for a stout, but was afraid that leaving over 2 pounds of dark grains for 10h in my mash would bring a lot of astringency :/

Of course the easiest solution is that I could have simply added the dark grains in the morning...But that would add 30min/1h and I wanted to finish the brew before family's up.

 

[BrewnWKopperKat]

astringency

The book Brewing Better Beer has a section on handling dark grains that may be of interest. It enhances some research that was done in the early 2000s that may be partially available via web searches. I tried

"mary anne gruber" "cold steep"

and

"mary anne gruber" "cold water extraction"

to see if I could get the same information that was in the book, but was only partially successful.

 

[J2W2]

To the million dollars question -- how does the final stout taste -- I'll post the result here in few weeks, and the full recipe if it turned out good

First, I was wondering how it turned out?

Second, hopefully not to hijack your thread, I'd appreciate any advice on an oatmeal stout I'll be brewing soon. It's a partial-mash, with the following grain bill:

1.5 lb Flaked Oats​

1.5 lb 2 Row​

12 oz Biscuit​

9 oz Crystal 60​

9 oz Pale Chocolate​

7 oz Chocolate​

6 oz Debittered Black​

3 oz Roasted Barley​

​

The last time I brewed it, I added the mash wort at flame-out (no boil), which I think smoothed it out some. For next time, I was thinking of removing the Pale Chocolate, Chocolate, Debittered Black and Roasted Barley from the partial-mash and cold steeping them overnight in 3-quarts of water. I have a few questions on this process:

1) With the dark grains removed, I assume it's fine to add the mashed wort to the boil?

2) Since I'm not counting on any gravity points from the cold steep, should I stick with the same amounts of dark grains I always use?

3) I assume there will be little to no sugars extracted, but do you at least cover the cold steep to prevent any spontaneous fermentation?

Thank you very much for your advice!

 

[HBearBrew]

Hi @J@W2,

It turned very fine and I'm still enjoying this keg very much, although the final attenuation was perhaps more than I was hopping for. I like my stouts full bodied and this one had quite a light body at the end for an 8% beer. I used Mangrove Jack's 42 (think US-05 with 80% attenuation) so perhaps I would advise for a yeast with a tiny less attenuation. What did you plan on using?

I love smooth oats stout! I have not brewed myself any partial mash or no boil myself, but from what I read in Palmer's book about this technique, the grain bill you outlined sounds quite balanced and right.

Re 1) I would say yes

Re 2) If you are truly not counting, yes it would be fine. But if you want to achieve a similar gain impact compared to regular steeping and achieve a full-bodied stout, then I would double the amount of grains and water used for the cold steep to make up for efficiencly loss. But in the end both appraoches are probably fine and will result in a great beer either way!

Re 3) You will get some sugar extraction, check the refractometer reading, and I did cover my brewing pot with the lid for better heat retention, although I did not seal it with foil or whatver, and it was totally fine. In my case, because it gets boiled afterwards, I didn't sweat too much about spontaneous fermentation. Any bacteria will get killed during the boil. In your no boil approach, I'm curious to hear about the result, altough I believe it will turn out fine, just an hunch.

Hope this helps

 

[J2W2]

Hi HBearBrew,

I've brewed this stout four times. I have a nitro tap, and I've played around with various stouts and porters, trying to find a good one. Ever since I brewed this oatmeal stout, I pretty much haven't done anything else on nitro.

I use Safale S-04, which shows an attenuation of 74 to 82, so I probably do get a little less than you are since US-05 shows 78 to 82.. My last one had an ABV of 6.38%, so not as strong as yours.

I think I'll probably stick with my current grain bill. I'm assuming a cold steep should extract as much color/flavor from the dark grains as the partial-mash did, especially if I let it go anywhere near 24 hours. I don't want to overwhelm it with the dark grains as it has a nice balance right now.

I added my last partial mash wort, which included the dark grains, shortly after flame-out.. I ran my chiller for a few minutes to drop my kettle wort to 190 F, added the partial-mash wort, waited a couple of minutes to pasteurize everything, and then restarted the chiller. I plan to do the same thing with the cold steep, so nothing should survive. I'll cover the cold steep with some foil, that should keep anything out.

I'll try to report back when it's done. I'm just nine days into a double IPA, so it'll be a month or so before I'm ready to fire up the kettle again, but the oatmeal stout is next in line.

Thanks for your help!