Mash conversion at 62°C (143.6°F)

[StevAmos]

I have been brewing using an original Grandfather (30L). I usually mash at 66°C (150.8°F) which produces beer that seems to have a thicker mouthfeel and taste sweeter than the beer from commercial breweries. I usually use Safale US-05 and generally get final gravity readings of between 1.015 and 1.020

I want to make a thinner beer and have just finished a new brew which I mashed 6kg of 2 row pale malt and 20L of water at 62°C (143.6°F). After an hour, the gravity of the mash was 1.060. Over the next 30 minutes I took readings and the gravity reached 1.065. At this point the wort tasted sweet and similar to a solution of white granulated sugar.

I mashed out at 75°C (167°F) for 10 minutes and took another reading before sparging. The gravity read 1.075 and the taste of the wort was thicker, more like like golden syrup.

My thinking, which may be wrong, is that the mash out activated the alpha amylase enzymes and produced dextrins (the golden syrup taste).

1. If that is the case, if I were to mash longer at 62°C, would the conversion of sugars by the beta amylase enzymes continue to push the gravity higher? I would then sparge at 62°C to avoid the production of dextrins to produce a thinner, less sweet beer?

2. Do alpha and beta amylase enzymes work on the same starches, or do they work on specific types of starches, meaning if only the beta amylase is activated not all the starches present in the mash will convert? I wonder as the 62°C mash seemed to slow at 1.065, but the gravity increased by 10 points after only 10 minutes of mash out at 75°C (from dextrins, I assume).

 

[YeastFace]

Are you calibrating your gravity reading for temperature?

A 10 point gravity jump from end of mash to end of mash out doesn't sound quite right to me.

 

[Stu's Brews]

I agree with @YeastFace - something seems a little odd with your gravity readings as they shouldn't jump up that much after mash out. If anything, they shouldn't really change at all as at 75degC you'll have stopped the enzymes from working at all.

How are you taking your readings? Are they temperature corrected?

The other thing I'd say is I'm not sure dropping your mash temperature so much is the right approach for fixing the initial problem of under-attenuation.

What is your expected final gravity for the beers you are producing?

66degC is a perfectly normal mash temperature so it could be something else at play here. Potentially could be an issue with something like the calibration of your temperature probe, high mash pH or yeast health and pitch rates.

 

[peebee]

@StevAmos: I think some of that are fine conclusions. You are using US-05 yeast which will be happy if you supply with simple sugars and none of those "dextrin" things (it, and many yeasts, will hack their way through most of the dextrin which will be of the short chain "maltriose" variety). And I guess you drink "keg" type beers, cold and "well carbonated" which is far more palatable as "thinner" well attenuated beer.

But what you have very wrong ... dextrin isn't particularly sweet, it does not taste like "golden syrup" ... it doesn't taste of anything much. But it has "weight". It doesn't make thin beer. It's not particularly good in cold beer. And some prefer it that way! I mash in the 66-70C range! (Okay, I do mash "Heritage" malts at 63-64C, but that's getting complicated ... and it's not for making fizzy keg).

I generally use maltriose adverse yeasts too. Like WY1099 and S-33. I've tried US-05 once, just the once!



Some proper "Lagers" break those statements: They'll be high dextrin, cold (ish) and fizzy (Bavarian Beers?). But there's always exceptions when making sweeping statements.

 

[The Baron]

How much yeast are you using at those higher gravities?
This may cause under attenuation if you are not using enough or the higher attenuating yeasts to suit

 

[Clarence]

I have been brewing using an original Grandfather (30L). I usually mash at 66°C (150.8°F) which produces beer that seems to have a thicker mouthfeel and taste sweeter than the beer from commercial breweries. I usually use Safale US-05 and generally get final gravity readings of between 1.015 and 1.020

I want to make a thinner beer and have just finished a new brew which I mashed 6kg of 2 row pale malt and 20L of water at 62°C (143.6°F). After an hour, the gravity of the mash was 1.060. Over the next 30 minutes I took readings and the gravity reached 1.065. At this point the wort tasted sweet and similar to a solution of white granulated sugar.

I mashed out at 75°C (167°F) for 10 minutes and took another reading before sparging. The gravity read 1.075 and the taste of the wort was thicker, more like like golden syrup.

My thinking, which may be wrong, is that the mash out activated the alpha amylase enzymes and produced dextrins (the golden syrup taste).

1. If that is the case, if I were to mash longer at 62°C, would the conversion of sugars by the beta amylase enzymes continue to push the gravity higher? I would then sparge at 62°C to avoid the production of dextrins to produce a thinner, less sweet beer?

2. Do alpha and beta amylase enzymes work on the same starches, or do they work on specific types of starches, meaning if only the beta amylase is activated not all the starches present in the mash will convert? I wonder as the 62°C mash seemed to slow at 1.065, but the gravity increased by 10 points after only 10 minutes of mash out at 75°C (from dextrins, I assume).

I'd be looking at the accuracy of my thermometer as well as the above. I mash at 66C and I never get an FG over 1010. I know my inkbiird thermometer reads a degree too high and, knowing that, I make allowances.
I also mash for at least 2 hours and often overnight.
Yes both enzymes (and the others like limit dextrinase) work in that temperature range; the higher temperature favours the alpha and the lower favours beta amylase.
Give it a try a 62C according to your thermometer and see if it suits you better. It certainly won't ruin the beer.

 

[StevAmos]

Are you calibrating your gravity reading for temperature?

I'm using a refractometer with wort straight out of the Grainfather. I will double check with a hydrometer and wort at 20°C during my next brew. I will also check the Grainfather probe to make sure the reported mash temps are accurate.

The other thing I'd say is I'm not sure dropping your mash temperature so much is the right approach for fixing the initial problem of under-attenuation.

I was hoping to achieve a thinner (less mouthfeel) tasting beer by preventing the production of unfermentable sugars. If that is the correct approach, is this achievable at 66°C. Or should I be using a yeast, other than US-05 that can eat more types of sugars?

@peebee. Yes, I would like achieve thinner, fizzier beer to be served cold from a keg. I love my oatmeal stouts but want to try some different styles. After reading your comment about dextrins not being sweet, I realise I don't know what would have caused the golden syrup flavour. At 62°C the wort tasted like white sugar but once mash out temperature had been achieved the wort tasted different, more fuller in body and syrupy. I assume this was the unfermentable sugars, but I have not idea.

How much yeast are you using at those higher gravities?
This may cause under attenuation if you are not using enough or the higher attenuating yeasts to suit

In the past I have used one packet of US-05 straight into the fermenter within the temperature range of the yeast. I have used Nottingham for the brew I mentioned in the original post which is happily bubbling away in my fermentation fridge.

---

Thank you all for the replies. What do you think are the main considerations when making beer with a thin mouthfeel?

 

[StevAmos]

Give it a try a 62C according to your thermometer and see if it suits you better. It certainly won't ruin the beer.

It will be interesting to taste the results. I will check my equipment for temperature accuracy.

 

[Agentgonzo]

I'm using a refractometer with wort straight out of the Grainfather.

Did you take account of temperature? As far as I can tell the "ATC functionality" of a refractometer is just the fact that it has a sticker labelled ATC on it

I've tried with mine, using hot wort, cooled wort and even hot/cool tap water. There is at least a 5 SG point difference (maybe more) using hot liquids. You can see the level change as it cools!

 

[Druncan]

I bought a SR UKAS calibrated thermometer Reeves Brewing, Distilling Bottling and Bar Supplies ages ago. Very delicate (I keep it in a tube like my saccharometers )

It's only accurate to a *C but i use a magnifying lens and a scientific process of 'simple juxtaposition' (Guessing/estimating) Every one of my digital temp probes needed calibrating - and probably re-calibrating when I can be bothered,,,,,

But as long as they all tell me the same 'lie' I can live with it!

(Ex UKAS lab manager)

 

[Stu's Brews]

I was hoping to achieve a thinner (less mouthfeel) tasting beer by preventing the production of unfermentable sugars. If that is the correct approach, is this achievable at 66°C. Or should I be using a yeast, other than US-05 that can eat more types of sugars?

You're thinking along the right lines. More residual sugars (higher finishing gravity) will result in a fuller mouthfeel.

However, I suspect that your beer should actually be finishing at something closer to 1.010 without adjusting the mash temperature. US-05 is quite highly attenuating and as mentioned previously a mash temperature of 66degC is pretty normal.

 

[dmtaylor]

1. If that is the case, if I were to mash longer at 62°C, would the conversion of sugars by the beta amylase enzymes continue to push the gravity higher? I would then sparge at 62°C to avoid the production of dextrins to produce a thinner, less sweet beer?

2. Do alpha and beta amylase enzymes work on the same starches, or do they work on specific types of starches, meaning if only the beta amylase is activated not all the starches present in the mash will convert? I wonder as the 62°C mash seemed to slow at 1.065, but the gravity increased by 10 points after only 10 minutes of mash out at 75°C (from dextrins, I assume).

As you have seen, conversion occurs at 62°C, but the effect is very slow and incomplete. If you wanted to conduct a mash solely at 62°C, the amount of TIME matters a lot. If for 60-90 minutes (pretty standard mash time for most people), you will end up with a lot of unconverted starches, which are not very fermentable and will lead to a starch haze in the beer, and could also reduce shelf life of the beer before exhibiting off-flavors due to any tiny amounts of contaminants by wild organisms that might be able to eat the starches more effectively than beer yeast can do. However, if you were to mash for a very long time, like overnight 8 hours or longer, these effects could be minimized and conversion maximized. Still, if you never conduct a mashout and go straight up to a boil, there are things beta amylase will not have been able to do for you, leaving a considerable amount of unfermentable dextrins behind, still resulting in reduced conversion efficiency and perhaps not the attenuation that you might desire. As such, it might be best still to do a short rest at any higher temperature from say 65°C to 75°C to gain some of these benefits (as you saw in this experiment).

Both alpha and beta work on nearly all starches, with exception of "limit dextrins", for which there is a separate enzyme called limit dextrinase. (But let's just set that aside because limit dextrins are honestly not a super big deal IMO.) Alpha is active at all mash temperatures including 62°C; it just works a bit slower at cooler temperatures. Beta is of course more fussy and is quickly denatures at higher "alpha" mash temperatures such as 68°C to 74°C.

Alpha behaves like an insane chainsaw massacre guy, waving his weapon around in all directions, quickly chopping starches and dextrins into smaller bits that the beta (if present) might then be more suited to work on. Beta, meanwhile, can only nibble off the ends of starches, dextrins, and complex sugars. The contribution of beta is important... but perhaps not as important as alpha because alpha is more sturdy and ever-present compared with beta. I think if you did a long mash (several hours to overnight) at a suitable alpha temperature such as 69°C to 72°C, where the beta is pretty much denatured leaving only the alpha, you can still achieve a highly fermentable wort, simply because alpha works faster and keeps on waving his chainsaw around, hitting everythng multiple times until everything is small fermentable bits, with some dextrins (unavoidable in most mashes regardless of temperature or time).

Beta is a fragile tool. Even at a low temp of 62°C, it is slowly denaturing, which could explain at least part of the effect you observed at that temperature. It takes a long time for beta to work, and there were certainly a lot of dextrins present until you raised up temperature for the alpha to help more to chop them up.

It's a complex system, but by golly it sure works. And it does help to try to understand the mechanics to help you to achieve your goals. If I were you, and I wanted a drier beer (lower FG)... I would simply mash at a slightly lower mash temp of 64°C, but not just for 60-90 minutes, but rather overnight. And if the temperature falls during that time, it's not a bad thing. TIME matters much much more than temperature. The enzymes are active enough at lower temperatures that, given enough time, they will perform quite well for you. I think your next step should be to mash overnight at a lower end temperature. You can insulate the mash tun, but if the temperature falls a lot, don't worry about it, it will still turn out fantastic.

Good luck.

EDIT: Starting to take a deeper look at your post (besides just the two questions) and some of the responses...

I tend to agree with others, you should check calibration of your mash thermometer, it seems it might be quite low or high compared with reality. A standard mash at 66°C for 60-90 minutes should give you higher attenuation / lower FG... especially with US-05 which can eat through more sugars than most yeasts! Something isn't right, probably the mash temperature/thermometer. The folks who said that are right on the money.

...AND, you should consider an overnight mash, as I had concluded previously. My initial response stands.

Best way to calibrate a thermometer is NOT just to check it against other thermometers! But you should check the temperature in known conditions: ice water (zero) and boling water (be sure to look up the boiling temperature for your elevation above sea level, it might NOT be 100!). Mash temperatures are roughly halfway in between, so you can average the errors at both ends to come up with a reasonable interpolation of the true temperature of the mash.

 

[Clarence]

Excellent advice from @dmtaylor . If you do mash overnight and you let the temperature fall, don't be put off if the mash pongs a bit in the morning. It's just the lacto bacillus present on the husk doing its thing. It'll lower the pH infinitesimally and the smell will disappear entirely before you've even finished the sparge.

 

[peebee]

Nothing wrong with what I said, but I perhaps overlooked this (or didn't put them together):

... I usually use Safale US-05 and generally get final gravity readings of between 1.015 and 1.020 ...

1.020 with US-05? Now that is wrong, and probably contradicts some of what I said? I'll fall in-line with the others. You appear to be mashing at higher temperatures than you think. I find that unlikely (it requires a significant temperature error to cause something so obvious) but I can't come up with a better reason. So ... your thermometer is misreading?

 

[peebee]

Are you pushing the temperature probe well into the Grainfather's socket (thermowell) ... that'd do it (make it under-read that is). The rubber about the probe should secure it firmly.

 

[StevAmos]

I will certainly test all my equipment. It could very well be that I'm getting a reading that is way too high.

Thanks for the advice. Also, @dmtaylor thanks for taking the time to write that detailed explanation. A lot of great ideas to ponder and experiment with, and a great excuse to make beer.

 

[dmtaylor]

Are you using a refractometer to measure your "final gravity"? When alcohol is present, a refractometer will not read accurately unless you enter results into a conversion calculator such as this one:

http://seanterrill.com/2012/01/06/refractometer-calculator/
Whether you are using a refractometer or a hydrometer for final gravity measurements, make sure it reads 0.0 or 1.000 in plain water, respectively. Maybe not only is your mash thermometer out of calibration, but perhaps also your final measurements are off.

 

[RoomWithABrew]

Wort pH, salts and post boil/ post ferment pH will also affect the taste.
Longer term if your ferment / package process causes oxidation that can also make your beer taste sweeter amongst other off flavours.
But I'd look at my mash bed temperature and duration first. Then pH salts, yeast nutrient, yeast volume and oxygenation, temperature control of ferment as well.
Using Dextrose in the " grain bill" can also paradoxically lead to a drier tasting beer.

 

[MashBag]

@dmtaylor. Brilliant post.

If you mash overnight why would temperature fall, can't you leave a grainfather running?

 

[RoomWithABrew]

@dmtaylor. Brilliant post.

If you mash overnight why would temperature fall, can't you leave a grainfather running?

Not sure @dmtaylor says he has a grain father, but agreed if grain father user should be able to do an overnight temp mash at a set temperature.