I’d like to brew a silky smooth oatmeal stout, like Samuel Smith’s. My previous batch used 1.5 lbs of flaked oats for a 5 gallon batch, the FG came out at 1.010. I did a single infusion mash at 154F (aimed for 156F but it came in low). Next time I’ll mash higher, but is there anything else I can do to boost the mouthfeel?
Use a higher percentage of oatmeal? Employ a protein rest? Alter the water chemistry?
Not sure a protein rest is in your interest. A little more oatmeal wouldn’t hurt and give it plenty of time for the glucans to come out. You can also use a little carafoam or other dextrin malt.
You could also mash a little shorter too. Try mashing for 45 minutes instead of 60, although I’m not for sure that will make the difference you’re looking for.
Have you checked the calibration of your thermometer and hydrometer? 1.010 seems awfully dry for an oatmeal stout mashed at 154°F. However, I’d mash warmer, not shorter, for more body.
I guess I meant with my suggestion to mash warmer and shorter. Say 158F for 30-45 minutes.
it’s a combination of factors. thermometer calibration is a good idea.
bay brewer didn’t mention his original mash time, nor what the rest of the grist was, but a 45 min mash is reasonable.
I was assuming he was doing the standard 60 minute mash.
me too. that or 90 min
I have a digital thermometer that I generally trust. I’ve had thermometer issues in the past but this one seems to be stable. That said I’ll check it in ice water and boiling water the next time I set up to brew. I always seem to loose a few degrees when I pour the liquor into my mash-tun, I haven’t dialed in how to adequately offset for that yet.
A few more details on the batch might be helpful: 60 minute mash, single infusion w/ mash-out, no sparge, OG: 1.055, yeast: Wyeast 1028 (London Ale). Dark grains were cold-soaked a day ahead of time so I didn’t add any salts to the mash.
tomsawyer: I’m not sure what you mean by “give it plenty of time for the glucans to come out”. I agree with the other posters that a shorter mash would help limit the wort fermentability, although I’m not sure how mash time would affect beta glucans. Figure 91 in Chapter 14 of Palmer’s book shows the active range of beta glucanase cuts off around 120 F, so a normal mash would denature that enzyme and prevent breakdown of beta glucan during mashing. Are you suggesting that the beta glucans need time to soak out of the grain? If so would doing a “rest” between mash-out and lautering do the trick?
Why not choose a yeast that finishes higher? Windsor comes to mind.
I’ve found that if you mash warm enough, there’s no need to mash shorter and take the risk of incomplete conversion. Of course a warmer mash will convert faster, so it’s less of an issue.
“Trust, but verify.”
I’d recommend getting a decent spirit filled thermometer (a “lab” thermometer) to calibrate the digital thermometer against. It should cost less than $10. The spirit thermometer should be accurate to start, but can be checked against ice and boiling water. That kind of thermometer should then be accurate in between those points. Then, check your digital thermometer against the spirit thermometer near mash temperatures.
The temperature you are looking for is the temperature of the mash in the mash tun. You’ll continue to lose heat to the tun for a few minutes after you mash in. You might want to also check the temperature after 5-10 minutes. You might find that you are mashing even cooler than you think, even if your thermometer is accurate.
154°F should give you pretty decent body for a beer the size of an Oatmeal Stout, but go warmer if you’re not getting as much as you want.
Ice water and boiling is one form of checking but you’d be much better off calibrating your thermometer in the normal mash temperature range. Use a certified thermometer like someone else suggested.
Another option, rather than trying to figure out the offset, is to just heat your liquor 5-10 degrees higher than your desired strike temp, dump it in, and wait til it drops to where you want it. Then add the grist.
Yeah but thats the only friggin’ time my tun holds temp really well.
How much crystal malt in the recipe? My oatmeal stout has never come in under 1.018 and often is 1.022.
I would defiantly check out the Thermometer and also mash at a higher temp. I normally mash my stout at around 156 for an hour when I single step. You can also add some more oats to bring up the mouth feel. I go with about a pound and a half on a 5 gallon batch.
[quote]Another option, rather than trying to figure out the offset, is to just heat your liquor 5-10 degrees higher than your desired strike temp, dump it in, and wait til it drops to where you want it. Then add the grist.
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The problem I see with this idea is your going to lose temp the moment you add your grist and are going to have to add more water to bring it up again. Depending on how big your turn is it may not be a good idea. If your having problems getting your mash temps right I would recommend a good brew program like beer smith or pro mash to help you out. Also keep some boiling water and cold water on hand in case you miss the mark one way or another. And lastly I would totally change the yeast you are using. I use White Labs Irish ale 004 and have found it works best for stouts. I’ve tried others but just don’t get the fullness of taste and feel I get with the WL yeast. Lastly take notes always and look at how your brew day went. The notes can help you isolate problems and make adjustments the next time and it has also helped me understand my equipment and how its working. Mash turn temps before you infuse, grain temps the whole nine yards. Ive found for instance if I preheat my mash turn to 72 degrees before I start, my temps stay more stable. Good luck and happy brewing.
The problem I see with this idea is your going to lose temp the moment you add your grist and are going to have to add more water to bring it up again. Depending on how big your turn is it may not be a good idea
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You misunderstood what I was saying. When I said “where you want it”, I meant the strike temp that you want (or your software calculated for you). Strike temp is higher than your desired mash temp by the amount “you’re going to lose the moment you add your grist”. So, by adding the water higher than strike and letting it drop, you’re eliminating the thermal mass of your equipment from the equation. Since thermal mass is the most unique and difficult to dial in parameter, eliminating the need to figure it out is “pragmatic” 
+1 this is the only way to do it
Since I am using a RIMS, i dough in a couple degerss lower (Celsius) and come up to rest. Reading this thread raises a couple questions i have:
Since strike water is usually pretty close to mashout temperature is there some denaturing going on when I dough in/mixing?
And, if you rest at a higher temp. for a long period will you get less body? I am always curious when i look at other recipies how much mash times/temps vary with the same style.Can anyone recommend some reading that helps “demystify” mashing?
I used the London strain with my English Mild and that stuff cranked pretty good. It turned out a couple points lower than expected and the perception was lighter than the gravity reading. You might try a less attenuative English strain.
Just to some food for thought, but adding oatmeal to a 1.050-1.060 stout isn’t gonna give it the same body as a 1.100-1.110 Russian imperial stout. Try the good tips others have offered, but keep your expectations within reason. You could always buy a bottle of Samuel Smiths and taste them side by side; you may not be as far off in mouthfeel as you think.