Questions on FG for partial mash brewing

[livelyjay]

Lately I've been having difficulty meeting the FG for my brews when I type everything into the online recipe builder. Looking back through my records I had much better success when I was doing all grain. My last few batches I've been around 1.06 OG and the FG is typically 1.016 - 1.020 depending on the yeast. Two batches using Safale US-05 got down to 1.016, but other yeasts are typically around 1.020. When I did all grain, I was able to get down to 1.010 on a 1.060 batch using US-05 or other high attenuating yeasts.

I add my LME at 15 minutes. I'm fermenting in my basement which is between 66 and 68 degrees. My boil volume is around 3 gallons. I haven't been using starters because I haven't been making big beers, nothing over 1.060. My typical partial process is steep for 60 @ 155 degrees, sparge with 0.5-1.0 gallons @ 170, top off to 3 gallons and boil for 60.

Why is this happening? The only thing I can guess is a partial mash has less boil volume so I'm getting some caramelization of the sugars. Any and all help on process, temps, etc are welcome because I want to do this correctly. I'll even switch back to All Grain if I need to

 

[BlueHouseBrewhaus]

You could be right about caramelizing, but extracts also usually seem to get lower attenuation. Extracts have a fair amount of unfermentables. There are even threads on here about "the curse of 1020". When I was doing extract I routinely ended up around 1.020.

 

[unionrdr]

I do pb/pm biab 5 gallon batches. I mash enough grains to use the wort & sparge from them for the boil. I add the extract @ flame out. since pasteurization happens in seconds @ 160F, & the wort is still boiling hot, it works great. you don't have to boil the heck out of it to pasteurize. It could be old LME, or some that has too many unfermentables in it. I only got stuck at or above 1.020 once. I can get 1.05X to 1.06X down to 1.010-1.012 routinely. How fresh ingredients are when you get them & how you store them factors into the outcome as well. How do you treat the yeast? Pitch dry or rehydrate?

 

[livelyjay]

How do you treat the yeast? Pitch dry or rehydrate?

The freshness of the LME is kind of out of my hands. I buy the 33lb growler and I go through it in a few months. It's stored in my basement at low temp and low humidity, not sure if that matters. I always follow the instructions of the yeast. So US-05 I just pitch it dry. Nottingham I rehydrate. Other than those two it's liquid yeast and I just pitch it.

 

[unionrdr]

I rehydrate all my dry yeasts as a matter of course. I also try to pitch at within 10 degrees of wort temp to keep a healthy pitch. It seems like it ought to be something to do with the extract? whether it's old or contains a lot of unfermentables?

 

[Calder]

You partial mash at 155 F. Seems high to me, and will generate a lot of unfermentables.

- What temperature did you mash at when you did AG?
- Are you using the same thermometer?
- Have you checked the accuracy of the thermometer?

Extract is generally less fermentable than AG batches, but it does depend on mash temperature.

 

[tennesseean_87]

You partial mash at 155 F. Seems high to me, and will generate a lot of unfermentables.

- What temperature did you mash at when you did AG?
- Are you using the same thermometer?
- Have you checked the accuracy of the thermometer?

Extract is generally less fermentable than AG batches, but it does depend on mash temperature.

This is what I was going to say. OP, even if you're mashing at 152 and getting these results, I was going to say compensate by mashing at 148. I'd at least try mashing at 152, if not 150 and see if that gets you what you want.

 

[livelyjay]

All grain I was probably closer to 150. My setup doesn't have an internal thermometer so I used my grilling thermometer before I realized you couldn't submerge though. If I go back I'll get a thermometer setup correctly.

I mashed at 155 because from my memory Brewers Best kits say to do the steep between 150 and 160 and never let it get above 170. Although now that I go back and read, it says 148-152 and never above 155. But I don't steep anymore than 3 pounds of grain. I wouldn't think the steep would cause that many unfermentables. Maybe that combined with the LME gives me the higher number of unfermentables. Just so I get things straight, what temps should I mash/steep and what temp should I sparge with? Also I want a slight rolling boil and not high intensity right? I'll make an identical batch and only adjust the temperatures to the correct range.

 

[BlueHouseBrewhaus]

+1 on the thermometer check. Also, what were the grains and amounts that you mashed? Could be a high percentage low/non fermentables.

 

[livelyjay]

I double checked the thermometer and it's good to go. Non LME ingredients were:
Munich 1.0
Amber .75
Crystal 20 .75

I put it in secondary today and the gravity has been at 1.016 for four days now.

 

[unionrdr]

^In ounces?^

 

[BlueHouseBrewhaus]

Those grains may have been closer to steeping than mashing. Munich may not have enough diastatic power to convert the other grains, especially if it was a darker munich. You might have been a little high on the unfermentables, which could explain the higher FG.

 

[livelyjay]

Those grains may have been closer to steeping than mashing. Munich may not have enough diastatic power to convert the other grains, especially if it was a darker munich. You might have been a little high on the unfermentables, which could explain the higher FG.

Not sure what any of that means, which is why I am here. Could you please elaborate? Apologies for mixing up my words. I am indeed steeping with a reusable nylon fine mesh bag. It was not a dark Munich, pretty sure the rating is 10L.

 

[Calder]

The title of the thread says Partial Mash. You did not provide grains. We assumed you were indeed mashing with a reasonable amount of base malt to get conversion of the starches.

Munich 1.0
Amber .75
Crystal 20 .75


Munich has only enough diastatic power to convert itself, Amber does not have enough to convert itself, and the Crystal has none. So you essentially steeped rather than mashed.

Most of the sugars you got from the grains would be unfermentable (from the crystal). You probably got some conversion, but not much from the other grains, and at 155 F would have a lot of unfermentable sugars.

With the bulk of the beer being LME + Crystal + high mash on what little extra you got from the Munich/Amber, it is not surprising that you ended up with an FG of 1.016 - 1.020 (from an OG of 1.060).

AG will be lower if you mash lower as you are creating a more fermentable wort.

To get your LME batch down, add a pound of base malt to the grains, and do a mini mash at 148/150 F, and maybe replace a pound of LME with a pound of simple sugar.

 

[livelyjay]

Now I realize I am totally a newb and didn't realize it, even though I've been making beer for two years. Time to try and understand what the hell is going on so I can do it correctly, plan for better recipes, and get better results.

Thanks for the information, but I'm still confused about diastatic power. Also I had no idea there was a scientific difference between steeping versus mashing. The assumption was steeping was just mashing with a grain bag at a different temperature.

To try and clarify what you're saying:
- There are some grains that convert starches to ferment-able sugar (Munich in this particular recipe).
- There are other grains which are simply for flavoring and only contribute unfermentable sugars.
- You mentioned the Munich only has the power to convert itself. That must mean there are other grains that can be used to convert other grains.
- The main purpose of mashing is done to convert starches to sugars.
- Steeping is done to pull flavors and character out of specialty grains, but yields unfermentable sugars.

Why would adding a pound of base and doing a mini-mash improve my results? Is it because it will convert itself and help convert some of the other grains (Munich and Amber)?

 

[unionrdr]

Yeah, base malts have more diastatic power to not only covert themselves, but other grains in the mash.

 

[Calder]

To try and clarify what you're saying:
- There are some grains that convert starches to ferment-able sugar (Munich in this particular recipe).
- There are other grains which are simply for flavoring and only contribute unfermentable sugars.
- You mentioned the Munich only has the power to convert itself. That must mean there are other grains that can be used to convert other grains.
- The main purpose of mashing is done to convert starches to sugars.
- Steeping is done to pull flavors and character out of specialty grains, but yields unfermentable sugars.

Why would adding a pound of base and doing a mini-mash improve my results? Is it because it will convert itself and help convert some of the other grains (Munich and Amber)?

Yes! I think you have pretty much summed it up.

Mashing is the process of converting starches to sugars. Generally you need about 30 Linter per lbs of grain. Linter is the unit off measurement of disatatic power. Munich malt is roughly 30 L, so can convert itself, but if you add it with other grains that have lower diastatic power. the result is you get below the 30 threshold. making it difficult to get conversion.

Mashing is also done with a controlled volume of water. If you have too much (say 3 lbs in 5 gallons), all those enzymes are too diluted to end up converting. Generally mashing is done with 1 to 2 quarts of water per lb of grain (some BIAB may use higher amounts).

Amber is about 20 L, and crystal has zero.

Crystal has some sugars from the method that creates it. These are mostly unfermentable, and makes this a good grain for steeping. Crystal does have starches that can also be converted if you have it in a mash with sufficient enzymes.

American base malts are about 120 L, this means a lb of 2-row can convert up to 4 lbs of grain. This is why I say add a lb of base malt.

I like to stay way above 30L for my mashes.

Mashing also involves controlling the temperature to determine how fermentable the resulting sugars end up being.

Steeping, is like steeping tea. You generally use grains that already have sugars, and also provide flavors (Crystal, Chocolate, black, etc). Steeping is limited in the number off grains it can do properly. Most off these grains also have starches that can be converted. Grains like Munich, Aromatic, Biscuit, etc need to be mashed to get any sugars and full benefit of the grain. Steeping is just dissolving the sugars from the grains into the water. It can be done at room temperature, but is more effective at higher temperatures.

 

[livelyjay]

Thank you so very much for all this information.

I found a nice blog HERE that lists out the lintner values for the base malts that I'll refer to from now on. Basically I've been steeping only and not mashing, hence why I'm getting a lot of unfermentables. Really the only change I need to make in my process is adding base malt to my specialty grains and keeping the temperature at 150 instead of 155. Looking back at the Brewers Best kits I did wonder why they included base malt along with the LME and now it totally makes sense.

I'm heading to the brew store very shortly to get the ingredients for my next batch. Thanks again for the help and happy holidays to everyone.