Low efficiency at low mash temperature

[Simonh82]

I brewed a West Coast IPA yesterday evening, or at least what I wanted to be an IPA. Instead I've ended up with a much weaker beer. I don't like sweet beers so I was aiming for a very low mash temperature of 62°C. I held this for 45 minutes before a slow 15 minute ramp up to 70°C where I held it for another 15 minutes.

At the end of the mash I thought it looked a bit different to normal. There were more small chunks of the white endosperm remained along with the grain husks than I normally see.

After the boil I chilled it through my counterflow chiller (which I'm still getting used to) and I managed to top it up with too much water. This was part of the reason my OG was only 1.043 when I was aiming for 1.053. Even with the extra water, my efficiency was way down from my usual 80-82% to about 75%.

Do you think this could be down to the low mash temp? I thought 45 min at the low temperature followed by a short rest at 70°C would make sure all the starch was converted.
The recipe only had Maris Otter, pale ale malt, light and dark Munich so should not have had any issues converting. When people do low temperature step mashes how long do you hold the mash rests for? Do you ever notice lower efficiency with these low temp mashes?

 

[ACBEV]

I don't like sweet beers so I was aiming for a very low mash temperature of 62°C

I find mashing @ 62c gives a sweeter wort, which is opposite to what you intended! Also @ 62c it takes longer to convert, so I don't think you mashed for long enough, giving poor efficiency.

I brew a London Best Bitter, which has an underlying sweetness to the beer. I mash as follows using a double mash method, this gives time for good conversion.

1st mash...
@ 62c - 30 mins - 2.5 L/kg
@ 67c - 30 mins - add boiling water to raise temp.
2nd mash...
@67c - 60 mins - rest of brew water

I think you should have mashed @65c to achieve your goal.

 

[Simonh82]

I usually mash at 65°C but I find that as I push up towards 6% abv a beer can get a little sweet even if it's mashed at 65°C. I wanted to have a play around with mash temps as its been a while since I've done so.

I think you are right that it must have needed longer to fully convert but I thought the higher temp mash rest would finish the job off.

 

[Ajhutch]

What temperature was your strike water? I wonder if there’s a vague possibilty that not all the starch was gelatinised. I have it in my head that barley malt starch gelatinises at 55-60C mainly but could it be that the particular malts you had in this mash need slightly higher?

Separately I think I’ve heard that nibbler amylase is slower than chopper amylase (I call them this as I can never remember which is alpha and which is beta) so maybe it’s as simple as that at that lower temperature a bit more time is needed.

 

[strange-steve]

For my last few brews I've been checking conversion at various points, and I've found that when step-mashing, starting around 62° and ramping up to 70° that it takes over an hour to reach full conversion.

 

[ACBEV]

I think you did a triple whammy with your mash...
1. @62c - Low efficiency - sweeter wort
2. @70c - Low efficiency - sweeter wort
3. Not enough time to convert.

The golden temperature zone is 65c to 69c. You can mash outside this zone, but it does take longer and may not have the effect you desire.

I still think you should have mashed at 65c. Maybe choosing a different yeast, with more attenuation.

 

[Simonh82]

St

What temperature was your strike water? I wonder if there’s a vague possibilty that not all the starch was gelatinised. I have it in my head that barley malt starch gelatinises at 55-60C mainly but could it be that the particular malts you had in this mash need slightly higher?

Separately I think I’ve heard that nibbler amylase is slower than chopper amylase (I call them this as I can never remember which is alpha and which is beta) so maybe it’s as simple as that at that lower temperature a bit more time is needed.

Strike water was at 68°C. The mash settled at 62.2°C. It was well stirred with a big balloon whisk and my mash paddle as I doughed in and a few times during the mash.

 

[Simonh82]

For my last few brews I've been checking conversion at various points, and I've found that when step-mashing, starting around 62° and ramping up to 70° that it takes over an hour to reach full conversion.

Thanks Steve. I'll give it more time if I try this again. Might just stick with my normal mash temp of 65°C for the moment though

 

[Ajhutch]

St

Strike water was at 68°C. The mash settled at 62.2°C. It was well stirred with a big balloon whisk and my mash paddle as I doughed in and a few times during the mash.

Ok so it’s not the gelatinising thing. Good to tick off possibilities!

 

[BeerCat]

I have been mashing low a lot recently and been getting good efficiency but i always mash for at least 90m often 2 hours. I use a refractometer every so often and its amazing how much more you get. I have also noticed a mashout almost always gives me an an extra 1brix( about 4 points). Normally by the time the wort is clear i cant extract more until mashout. Typically been mashing in at 62c for an hour then 68c for another hour followed buy a 15m mashout at 75c. I will say i was expecting a much drier beer from this mash schedule as my lagers seldom get below 1010.

 

[ACBEV]

I will say i was expecting a much drier beer from this mash schedule as my lagers seldom get below 1010.

Your described mashing method you use will produce a sweeter wort. It seems counter intuitive that starting at 62c will do this, but it does. What you are doing is very similar to the method Fullers use for London Pride... 30mins @ 62c... 2 hours @ 67c. London pride is not a dry beer.

 

[strange-steve]

Your described mashing method you use will produce a sweeter wort. It seems counter intuitive that starting at 62c will do this, but it does. What you are doing is very similar to the method Fullers use for London Pride... 30mins @ 62c... 2 hours @ 67c. London pride is not a dry beer.

Are you saying that mashing at 62 will give a sweeter beer than mashing at 65?

 

[ACBEV]

Yes... I believe so (everything being equal!). In my experience when brewing my bitter, starting at 62c and finishing at 67c gives a sweeter beer than at 65c. I know it is, or was a method employed by Fullers and I've read a few things on the interweb that concur with the concept. It might be the combination of the two (62c and 67c), but I can taste an underlying sweetness difference from mashing at 67c alone.

 

[Dutto]

I follow these principles:

Strike Water normally at 80*C but adjusted to suit grain bill, ambient conditions and required Mash temperature.
Strike Water = 2.6 litres per 1kg of grain
Mash at:

o 55*C to 66*C (High Alcohol - dry) or
o 68*C to 72*C (Low Alcohol – sweet)​

for one hour.

DO NOT exceed 75*C.

Stir after 20 and 40 minutes.

Heat SPARGE water 80*C to 85*C.

Lauter until wort runs clear and then Sparge at one litre per minute.

Stop sparge when runnings reach SG1.008 / SG1.012 or when the Boiler full.
​

Enjoy. :thumb:

 

[strange-steve]

@ACBEV Interesting. Is it possible that it's maltiness rather than sweetness you detect? I know that step mashes (63-70-77c) are used by German brewers to give higher attenuation while accenting malt flavours .

 

[ACBEV]

@strange-steve Possibly you are spot on. It certainly makes a difference that I like and doesn't make the beer taste dry.

 

[Simonh82]

I follow these principles:

Strike Water normally at 80*C but adjusted to suit grain bill, ambient conditions and required Mash temperature.
Strike Water = 2.6 litres per 1kg of grain
Mash at:

o 55*C to 66*C (High Alcohol - dry) or
o 68*C to 72*C (Low Alcohol – sweet)​

for one hour.

DO NOT exceed 75*C.

Stir after 20 and 40 minutes.

Heat SPARGE water 80*C to 85*C.

Lauter until wort runs clear and then Sparge at one litre per minute.

Stop sparge when runnings reach SG1.008 / SG1.012 or when the Boiler full.​

Enjoy. :thumb:

Usually I follow a fairly similar procedure. I heat my strike water to 70°C, as I BIAB the greater volume of water means the temperature only drops 5 degrees to 65°C. I mash for 45 minutes to an hour before raising the temp to 75 for a mash out. After that I do a 10 minute dunk sparge with 85°C water.

That normally gives me a solid 80-83% efficiency and produces a nice fermentable wort.

I have settled on a couple of house strain of yeast, both of which I really like the quite characterful flavour of. Both English ale strains which attenuate to 72-78% depending on mash temperature. That's fine for session strength beers but when I push the OG up to 1.053 I would prefer not to be left with a beer than finishes at 1.014. That's why I wanted to try the low mash temperature.

 

[Duxuk]

I have the opposite problem. I overnight mash and it's easy to end up with a dry finish. Extending your mash time would be my first change. A higher attenuating yeast may also give you what you want.

 

[Simonh82]

I've overnight mashed before and have indeed ended up with higher attenuation. Unfortunately this doesn't often fit in with family commitments. I need to squeeze a brew in after I've got the kids into bed and they are up bright and early the following morning so brewing then isn't really an option.

I think if I do go for this very low mash temp again (and I probably won't bother), I'll make sure I get to mash in earlier so that I can leave it for much longer.