Low efficiency, or how my mash temperatures sucked

[banesong]

Okay, just brewed my christmas cookie stout partial mash yesterday and missed my OG by 8 points (estimate of 1.058, hit 1.050). I realize that this is probably due to my temperature dropping to 145 at the end of the mash period (last 15 minutes). My questions are as follows:

- In the future, should I extend the mash period to allow for the potential of a low effeciency?
- How to tell the level of conversion in a mini mash when all I have is a hydrometer?
- Should I estimate the loss of gravity and and additional Dry Malt Extract at the end to make up for the difference?
- Will the lack of OG affect the sweetness/mouthfeel of the final product?

TIA
T

 

[nebben]

When you say that you estimated an OG of 1.058, how was this estimated? Original gravity into the fermenter? Mash efficiency? With this, the estimate is based on a percentage of your efficiency. What was the percentage you used, and is it a number that you've been able to attain in the past?

With a software like Beersmith, I think the default efficiency that it spits out is 75%. This number is arbitrary and you may get higher, lower or right on it depending on a lot of factors. The quality of crush of your grains, thickness of the mash, sparging method, and how much you leave behind are some things that can affect your mash efficiency. Did you take a measurement pre-boil as well as post-boil?

As far as your questions go, you can easily test for starch conversion by doing a simple iodine test. Pull a few drips of wort out of your mash tun after 30-60 minutes when you want to test conversion. Mix in a few drips of iodine. If the iodine/wort mix turns purple, you've got starches in the wort still and conversion is not done or is still happening. If the mix stays the color of iodine, then there aren't any starches.

Before extending the mash period, make sure your numbers, 1.050 in this case, are taken in the right context. I prefer to use brewhouse efficiency, since it takes everything into account from mashing to the end of the boil. A long boil with a lot of evaporation will improve your brewhouse efficiency, at a possible cost of making a more bitter beer unless hops additions are shifted. I guess what I'm rambling on about is that taking measurements pre-boil and post-boil will help you figure out where your problems are, and how to best fix them.

When I say to take measurements, some things to keep in mind:

• Record the volume of your wort you collect pre-boil.
• Don't trust a hydrometer above 80F, even with a temperature conversion chart. These things can be way off if they're warm. I only trust chilled to ~60-65F measurements.
• Take these measurements before and after the boil. Boiloff will result in higher gravity, which affects brewhouse efficiency.

When in doubt, if you are hoping for some efficiency, say 75%, and you find that your pre-boil calculations show a mash efficiency that wont result in 75% brewhouse efficiency after your boil, then have some extract on hand to boost it up.

 

[kyleobie]

It could be lots of things. My efficiency went from ~68%ish to ~75%ish when I switched from an online retailer to a LHBS.

 

[banesong]

Where to start.

The estimate of 1.058 was from Hopville [http://hopville.com/recipe/918773/oatmeal-stout-recipes/spiced-cookie-stout] (I haven't invested in Beersmith yet), and this is the first time I have made the beer. I will say, this is also only the second time I have crushed my own grains; I will try and take a pic next time to validate the crush, but it was better than what I get from the LHBS (some flour, crushed hulls, almost none intact). I didn't try and do an iodine test; I don't have any on hand.

The gravity was taken post boil, and though the wort was a bit high (74), I think it was pretty well there. What type of number would I be aiming for if I take a gravity reading pre-boil; is there a typical percentage of the og that I should expect?

 

[nebben]

Crappity crap, I just read the part about 145F during the end of your mash and missed it totally in the other post.

Cooler mash temps can take longer to get full conversion than at hotter temps. What was your original temperature? Did you stir up the mash and break up doughballs? How much water did you sparge with? How much volume did you collect into your fermenter?

Maybe a longer mash duration like you suggested would be helpful in this situation. If you collected more than 5G, that could explain some of the difference too. Otherwise, your mash temp/duration, crush, and sparging could make up the rest of it.

I wouldn't sweat the brew- 50 is still a good gravity. For your next batch, assume that your mash efficiency will be lower and have some extra extract on hand if the mash doesn't pan out. My rough calculations show that your mash efficiency was about 58% or so. In this case, a pound of light extract would get it up to 1.059-60'ish. Your grains contributed about 1.023 of the gravity, so if you improve on that, then you're doing good

 

[C-Rider]

Time to kick up the $20 and get beersmith. Another $60 should get you a refractometer. Divide that by a few beers brewed and they ain't to expensive.

 

[JuanMoore]

I realize that this is probably due to my temperature dropping to 145 at the end of the mash period (last 15 minutes).

Maybe, but not likely. As long as your temp was in range for the 1st 20-30 min, you likely had full conversion. More likely causes of low efficiency are crush, or sparge process. What was the initial rest temperature? What kind of vessel were you mashing in?

- In the future, should I extend the mash period to allow for the potential of a low effeciency?

Not unless you're having conversion issues, which is unlikely.

- How to tell the level of conversion in a mini mash when all I have is a hydrometer?

Don't confuse conversion with efficiency. You likely had full conversion, meaning that all of the starches were converted to sugars, but had trouble extracting those sugars from the grain effectively. A $2 bottle of iodine from the drugstore is all you need to test conversion for hundreds of batches. IMO it's not really necessary unless there's something that indicates that you're getting incomplete conversion.

- Should I estimate the loss of gravity and and additional Dry Malt Extract at the end to make up for the difference?

The common method is to take a sample once all of the wort is in the kettle and mixed well. Once the sample is cool you can take a hydro reading, and if the pre-boil gravity is lower than anticipated add some DME in the last 15-20 of the boil.

- Will the lack of OG affect the sweetness/mouthfeel of the final product?

Yes, but it will still be beer, and probably pretty good.

What type of number would I be aiming for if I take a gravity reading pre-boil; is there a typical percentage of the og that I should expect?

Depends on what your boil off rate is. You can convert the SG to PPG and do the math manually to determine the change in SG when concentrating by x gallons of boil off, or you can use the more popular method and use a brewing program like beersmith, brewtarget, etc. Either way, you need to be very precise in measuring all of your volumes for any hope of an accurate calculation.

It takes a few batches to figure out what the boil off, dead space, and efficiency is using your particular equipment and process. Once you have a process dialed in and know how it behaves, you can adjust recipes to hit the numbers exactly every time.

 

[Malticulous]

Marris Otter dosen't have real high diastatic power and the other 60% of the grain bill is other grains it had to convert. That mash needed extra time even at a higher temp.

 

[banesong]

Crappity crap, I just read the part about 145F during the end of your mash and missed it totally in the other post.

Cooler mash temps can take longer to get full conversion than at hotter temps. What was your original temperature? Did you stir up the mash and break up doughballs? How much water did you sparge with? How much volume did you collect into your fermenter?

Maybe a longer mash duration like you suggested would be helpful in this situation. If you collected more than 5G, that could explain some of the difference too. Otherwise, your mash temp/duration, crush, and sparging could make up the rest of it.

I wouldn't sweat the brew- 50 is still a good gravity. For your next batch, assume that your mash efficiency will be lower and have some extra extract on hand if the mash doesn't pan out. My rough calculations show that your mash efficiency was about 58% or so. In this case, a pound of light extract would get it up to 1.059-60'ish. Your grains contributed about 1.023 of the gravity, so if you improve on that, then you're doing good

Yeah, wasn't really worried about the gravity, more the potential sweetness of the end product or the flavor affect. Never mind that I accidentally threw star anise in the boil rather than allspice.

My initial temp was 165, with a drop to about 158 or so when the grain went in. I am doing a minimash/biab - I stirred it up, but as best I can in a nylon bag. My sparge process probably left a bit to be desired, and a bit of wort on the counter too, as 6# of grain is twice the bill I have used in the past, and it was a bit more than my colander could hold, and wider that the pot I was sparging into. The total collected was about 2.5 gallons, added to another 2.5 of preheated water. I sparged with another 8 quarts for my boil volume.

I will have to design another big(ish) beer to try and hit my numbers again - my typical beer ends at 1.040 (I like sessions!).

 

[banesong]

Time to kick up the $20 and get beersmith. Another $60 should get you a refractometer. Divide that by a few beers brewed and they ain't to expensive.

I may look into refractomers. The price of beersmith isn't why I haven't gone there yet - I use Hopville/Beercalculus, as I like the portability (I do a bit of *recipe smithing* at work), and the ability to share.

 

[Malticulous]

I have Beersmith and seldom use it. I have a refractometer and don't trust it.

 

[banesong]

Maybe, but not likely. As long as your temp was in range for the 1st 20-30 min, you likely had full conversion. More likely causes of low efficiency are crush, or sparge process. What was the initial rest temperature? What kind of vessel were you mashing in?

The inital temp was 165, with a drop to about 158 when the grains mashed in. I am using a cheap(ish) SS pot (5gal) as my mash vessel.

Don't confuse conversion with efficiency. You likely had full conversion, meaning that all of the starches were converted to sugars, but had trouble extracting those sugars from the grain effectively. A $2 bottle of iodine from the drugstore is all you need to test conversion for hundreds of batches. IMO it's not really necessary unless there's something that indicates that you're getting incomplete conversion.

I will stop by and get the iodine; I think for the next few beers, I will double check the conversion.

The common method is to take a sample once all of the wort is in the kettle and mixed well. Once the sample is cool you can take a hydro reading, and if the pre-boil gravity is lower than anticipated add some DME in the last 15-20 of the boil.

As I am currently on a minimash basis, I will always need to add DME, it is just the amount of DME I need to adjust.

Yes, but it will still be beer, and probably pretty good.

I dunno; you should see the amount of spices the SWMBO made me add.

Depends on what your boil off rate is. You can convert the SG to PPG and do the math manually to determine the change in SG when concentrating by x gallons of boil off, or you can use the more popular method and use a brewing program like beersmith, brewtarget, etc. Either way, you need to be very precise in measuring all of your volumes for any hope of an accurate calculation.

Ack, math! I will probably need to invest in beersmith one of these days.

It takes a few batches to figure out what the boil off, dead space, and efficiency is using your particular equipment and process. Once you have a process dialed in and know how it behaves, you can adjust recipes to hit the numbers exactly every time.

Sigh. I may just have to move to the keggle and outdoor burner before I really try to dial in the process.

Thanks again!

 

[banesong]

I have Beersmith and seldom use it. I have a refractometer and don't trust it.

How do you formulate your recipes then, and what do you use, a hydrometer?

 

[JuanMoore]

Now that I went back and read the recipe, Malticulous might be right about the conversion. Maris Otter doesn't really have particularly low diastatic power, but even 6-row would have trouble converting everything using such a small quantity relative to the amount of grains with little or no diastatic power.

There are plenty of free brewing programs (brewtarget, brewcalculus, etc), but they're not as comprehensive or as easy to use as beersmith. You might need to use more than one of the free programs to be able to do everything you want. Beersmith is far from a necessity, but it is a nice thing to have.

Refractometers are nice to be able to take quick readings on brew day, especially if you fly sparge, but are useless once fermentation has started. I've used a couple of them before, but never seen the need to buy one for myself. You're going to need a hydrometer for all readings after fermentation has started either way.

158F to 145F over 45 min is a huge drop in temperature. You need to either insulate the pot somehow during the mash, stick it in the oven on low, or apply a little heat from your burner to keep the temps more stable. How well did you stir at dough in? It takes more stirring than one might think to fully incorporate the grains and equalize temps throughout the mash tun. If you weren't fully doughed in the temp may not have fully stabilized when you took the 158F reading, and your mash temp may have been lower than you thought.

 

[banesong]

Yeah, I have a hydrometer; have somewhat lusted after a refracometer - can't justify the cost.

Would you suggest increasing the marris otter in the grain bill to help the conversion?

 

[JuanMoore]

Would you suggest increasing the marris otter in the grain bill to help the conversion?

Or maybe add some 6-row since it generally has the highest diastatic power. The total diastatic power of the recipe is probably somewhere around 40L, which is technically enough to convert, but low enough for it to take a long time. Mashing for 90 min would probably work well. For a more standard conversion time, a pound of 6-row would boost you to ~80L. You'll want to decrease the DME a little to make up for any fermentables that you add.

 

[nebben]

Maybe it's how did BIAB wrong, but when I've done it in the past, I have never cracked 60% efficiency with it. I always thought my problems were from the trouble I've had trying to rinse the grain that is in the bag.

 

[passedpawn]

- In the future, should I extend the mash period to allow for the potential of a low effeciency?

Yes. The mash continues to become more fermentable well after the standard 1 hour mash. (see fermentability studies). At low mash temps, I think enzyme activity is slower and benefits from a longer mash anyway.

- How to tell the level of conversion in a mini mash when all I have is a hydrometer?

No good way AFAIK. Hit your temps.

- Should I estimate the loss of gravity and and additional Dry Malt Extract at the end to make up for the difference?

You could do that, but I prefer to measure gravity during the boil (refractometer). and continue the boil until I get to my intended gravity. If you extend the boil, be careful with the hops additions (once you start adding flavor hops you are locked into your boil time). Getting beersmith is a good idea - it'll let you know what your preboil gravity should be. Also, if you learn the simple C1V1 = C2V2 gravity-volume relationship, you can quickly figure out what your post-boil volume needs to be given a preboil gravity measurement. PM me and I'll go over that with you.

- Will the lack of OG affect the sweetness/mouthfeel of the final product?

Yes, but probably not too much, you might even like it better this way. There are much bigger mistakes you can make, believe me, I've made some doozies

 

[banesong]

Thanks everyone!