oatmeal cream stout fg 1.032?

[worldofilth]

Hi I'm new posting here but have been reading the forums for a couple of months. I recently attempted my first 5 gallon brew and went with northern brewers buffalo sweat clone (also my first attempt at a partial mash). During the partial it ended up mashing around 130-135* for about 3 hours, this may be the cause for my problem I'm not sure. Anyway everything else went well pitched the yeast and no visible activity in the air lock since, there is a very small ring maybe an 1/8 of an inch above the liquid. My starting gravity was 1.058 which what the instructions said it would be, I also added a pound of lactose sugar instead of a half during the boil. Took a gravity reading ~3 days later and it was 1.032, that was 4 days ago and it is still the same. The ambient temperature has been between ~50 at night and ~65 in the day. I used wyeast 1098 left out of the fridge for a few hours as per the instructions. So just wondering what the general opinion is, did I screw up somewhere, my temp to cold, pitch more yeast, RDWHAHB, it's normal, or something else?
Thanks in advance for any advice I receive

 

[CraptainWirtz]

Was the whole mash at 130-135 degrees? What was your grain bill? Did it spend any time at 140-160 degrees? Are you using a hydrometer or refractometer for your gravity readings?

Some quick googling tells me that lactose contributes ~36 points per pound per gallon (ppg). So assuming a 5 gallon batch, one pound of lactose will contribute 36/5=7.2 points to your final gravity. But that leaves your non-lactose FG at 1.025, which may still be too high. If you answer the questions above, some folks may be able to give more advice.

If you really steeped your grains at 130-135 for 3 hours, you may have a lot of starch in your beer rather than fermentable sugars and your current FG may be truly the end. But it's hard to say without more information.

 

[insanim8er]

1.032 is way too high--regardless of the lactose. Your fermentation temps are way too cold, so it's going to take forever and be a slow fermentation. You want to be at 64, but not 50.

Also what Captain said above is not accurate. Mashing at low temps (below 153) yield a dryer beer. This means the sugar is more fermentable. Temps above 153 create complex sugars that are less fermentable. I assume the grains you steeped wasn't really used for the sugars. They're more for the color.

It sounds like a your fermentation has stalled... Trye rousing the yeast (carefully swirl the wort around to get it back into suspension) Raise your temp up, so it doesn't go below 64 at night. The other issues could be possibility of low oxygen and or bad yeast. If rousing and raising the temp doesn't work, pitch more yeast. I'd say to pitch a packet of US05.

BTW what yeast did you use?

 

[max384]

Was the whole mash at 130-135 degrees? What was your grain bill? Did it spend any time at 140-160 degrees? Are you using a hydrometer or refractometer for your gravity readings?

Some quick googling tells me that lactose contributes ~36 points per pound per gallon (ppg). So assuming a 5 gallon batch, one pound of lactose will contribute 36/5=7.2 points to your final gravity. But that leaves your non-lactose FG at 1.025, which may still be too high. If you answer the questions above, some folks may be able to give more advice.

If you really steeped your grains at 130-135 for 3 hours, you may have a lot of starch in your beer rather than fermentable sugars and your current FG may be truly the end. But it's hard to say without more information.

Actually if he mashed at too low of a temperature, the beta amylase would be more active, and he would have more fermentable sugars in his wort, thus a drier lower FG beer. A higher mash temperature leads to more alpha amylase activity, which will lead to more nonfermentable sugars and a higher FG.

 

[CraptainWirtz]

I'm just not sure beta amylase is all that active at 130-135. With very little beta or alpha amylase activity, I'm thinking you'd end up with a wort that is even less fermentable than one mashed at 158-160 degrees. According to Braukaiser (http://braukaiser.com/wiki/index.php?title=The_Theory_of_Mashing), the optimal temperature for beta amylase is 140-150 degrees. That's why I asked if the mash was truly nothing but 3 hours at very low temperature, or if that was due to accidental heat loss and the mash spent some amount of time in the mid-150s.

 

[CraptainWirtz]

Also, I missed the part where it's only been fermenting 7 days. Probably too early to be concerned about a higher than expected SG. But it wouldn't hurt to rouse the yeast as suggested above.

Another question - are you monitoring the temperature of the fermenter itself? That's a much more useful value than the ambient temperature.

 

[max384]

I'm just not sure beta amylase is all that active at 130-135. With very little beta or alpha amylase activity, I'm thinking you'd end up with a wort that is even less fermentable than one mashed at 158-160 degrees. According to Braukaiser (http://braukaiser.com/wiki/index.php?title=The_Theory_of_Mashing), the optimal temperature for beta amylase is 140-150 degrees. That's why I asked if the mash was truly nothing but 3 hours at very low temperature, or if that was due to accidental heat loss and the mash spent some amount of time in the mid-150s.

This is a good point. I always read that beta amylase is active at 130-150, but it may not be very active at the low end of that range.

 

[insanim8er]

I'm sure someone who has a higher degree in science than I do can put this straight, but the optimal mashing temps take more into consideration than simply converting simple vs complex sugars. It also takes into account the TIME it takes to convert these sugars.

He was mashing very low, but he mashed for 3 hours. I believe he would still convert simple sugars over for that period of time at that low of a temp.

Regardless, I highly doubt that's his issue. He got most his sugars from malt extract, so his FG shouldn't be that high.

 

[CraptainWirtz]

I'll try. Think of the starch molecule as a tree branch (I read this analogy somewhere so I can't take credit for it). Beta amylase can only chew off maltose units from the end of the branch, and once it gets to a branch point, it can no longer produce maltose. I don't know what percentage of the "branched" barley starch (amylopectin) is digestible by beta amylase alone (that is, how far until a branch point), but it's certainly less than the combination of beta + alpha, because alpha chops the tree branch randomly, freeing more beta-digestible ends.

You're right that time is also an important parameter, but I don't know of any data showing what happens in an extra-long mash. We can perhaps extrapolate from the following graph:

I stole this from the page I linked a few posts above. 130-135 F is 54-57 C. So after the first ~60 minutes of mashing at 54-57 C, the beta-amylase is only about 60% active, and after 90 minutes of mashing it's only about 50% active. So given that beta amylase can only digest one end of the molecule and it has reasonably low activity at this temperature, my feeling is that it's a very inefficient mash.

I did look up the recipe for the PM Buffalo sweat, and it has about 5 pounds of grain, so it seems like that may contain enough starch that, when unconverted, may contribute to a higher than expected FG.

Of course, this is all academic and there's nothing the OP can do at this point but perhaps raise the temperature a bit and rouse the yeast.

 

[worldofilth]

Thank you everyone for your responses, so it sounds like either I screwed up my PM (crappy 40 year old stove/oven was the cause of the low temp) or my yeast is cold and sleeping guess I'll try gently stirring it into suspension and keeping it somewhere warmer, I haven't been monitoring the temp of the fermentation bucket cause I don't have a thermometer. The temp range I gave is just a guess but shouldn't be too far off. And I've fermented 4 2 gallon batches in the same place same temp with no issues. I'm using a hydrometer to measure gravity. Grain bill is 2# briess pale ale malt, 1# English roasted barely, 1# German Vienna, 0.5# flaked oats, 0.5# briess victory, and 0.375# English black malt, and I used wyeast 1098. Hope I answered all the questions you guys had and again your advice is much appreciated