Consistently Low OG

[vrstud]

Hello Fellow Brewers:

I have recently started home brewing and so far have made four batches. I have kept meticulous records (being an engineer and all) and I have noticed that my OG is low for the amount of extract that I am putting in.

So far all my batches have been are from extract as I haven't committed to the equipment for mashing grains myself. I have made two kits and two IPA extract recipes. I would say that all of them have had low OG readings. If we focus on the last two batches they called for:

Strong IPA:
1lbs of crystal grains (steeped)
8.5lbs LME - I used Muntons Plain Light Malt Extract
1 oz Galena Hops 60min
1 oz Northern Brewer Hops 30min
1 oz Amarilo 30 min
1 oz Amarilo Dry hop day 7 fermentation

OG was 1040 at 22C. Based on my research this is 23 points low (1063) for what 8.5lbs of extract should generate. We added 12oz of dextrose to bring it up to 1050.

Imperial Black IPA
250g Victory malt (steeping)
250g Roasted Barley (steeping)
11.44lbs of LME - I used Muntons Amber Malt Extract
1 oz Columbus 60 min
1 oz Columbus 15 min
2 oz Chinook 5 min
1 Dry Ale Yeast

OG was 1064 @ 28C (the temp was hi but temperature only has a minimal effect on gravity readings - like 1-2 points). Based on my research this is 21 point low (1085) what 11.5lbs of extract should generate. We didn't add anything extra to this.

I saw similar things from the first two kits but I didn't keep the instructions which have the expecting OG.

Thinking I'm a noob and don't know what I'm doing I took the OG measurements several times for the last two batches (we did them on the same day). One was in a pale which made the measurement easy. The other was in a test tube. I checked and double checked. Still low.

The beer is fermenting well and my FG are what I expect, 1010 to 1014. The first two beers came out nice. The second two will be bottled this weekend. Initial tastes are good.

I have done a two point calibration on my hydrometer. Water reads ~998. A mixture of 12g/88g sugar to water gave me the expected increase of 48 to 1046.

So:
- I think I can read the hydrometer correctly.
- I know my hydrometer is calibrated (more or less)
This leads me to believe my reading are correct. Which means my LME is not getting me the desired OG I am expecting. Or my expectations are wrong.

The LME I am getting is from the local home brew store. They sell it in their own containers. I think they buy it in bulk and repackage it. Could it be too old? Could it be weaker than expected? From my research Muntons is a respectable brand.

Are my expected OG for 8.5 and 11.5lbs of LME correct?

Any help or insight would be appreciated as to why I am reading 20 points low consistently on my OG.

Regardless I am drinking tasty, if not weaker than expected, beer.

Chris


TLDR: Are there different LME and do they effect the OG significantly? By 20 points for 8.5lbs of LME?

 

[FloppyKnockers]

That is pretty low. I can usually get around 1.050 with 7.5 lbs. light LME. What's your brewing process?

 

[Qhrumphf]

Are you topping up with water prior to taking your reading? If so, that's your answer right there. It's not the gravity that's wrong, it's the measurement.

Different extracts can have different sugar contents but it shouldn't be significant. A couple points, if that. If follows, given that you're essentially adding sugar content of a reasonably consistent source to water, the gravity is going to be right. If you have the right volume and the right amount of fermentables, it's going to be correct.

However, pour a little honey into a glass of water. They don't mix easily (they will eventually through diffusion, but that takes a while). If you top off, then take a reading, and don't stir it like it owes you money, you're often going to either grab more top off water than wort and get a reading that seems low, or grab more wort than top off and get a reading that seems high. When in reality everything is where it should be.

So end point, if you were supposed to have 5 gallons in the fermenter and you had 5 gallons in the fermenter, and you added the right fermentables, ignore your reading and just trust what it was supposed to be.

 

[meatcleaver]

pretty much impossible to miss your og with extract as long as your final volume is correct.
I would assume this is a partial boil & that you top up your fermenter with bottled water to reach final volume? if so, then I'd say more than likely your experiencing wort stratification. your warm, high gravity wort is not thoroughly mixed with the cool water & so its throwing off your measurement.
anytime I brew an extract kit I assume the og to be what the kit predicts & just check the fg after 2 weeks or so in the primary.

 

[vrstud]

Hello:

After my first low OG, I read this on the internet and it explained why my first batch was low. I topped up the carboy and didn't mix so my sample was mostly my top up value.

For the last two batches, it was a 2.5 gallon boil, added to 2.5 gallon in the carboy for one batch and 2.5 gallon in the second batch. Both batches were total of 5 gallons. I picked up the carboy and mixed it up really well for a couple of minutes bouncing it on my knees. Both batches were well mixed before I took my measurement.

I'm going back to the store to see if they have heard of anyone else having issues with this LME.

 

[vrstud]

I'm going to relax and have a home brew.

 

[Qhrumphf]

I'd still doubt the reading before I doubt the gravity contribution of the extract.

Could your volumes be off? How are you measuring volume? The premarked lines on fermenters are often wrong.

 

[ncbrewer]

I picked up the carboy and mixed it up really well for a couple of minutes bouncing it on my knees. Both batches were well mixed before I took my measurement.

This method doesn't sound like enough for complete mixing. Looks to me like your sample wasn't representative. I stopped taking OG readings a few years ago after finding they came out right if I kept mixing long enough.

 

[madscientist451]

Hello Fellow Brewers:

I have recently started home brewing and so far have made four batches. I have kept meticulous records (being an engineer and all) and I have noticed that my OG is low for the amount of extract that I am putting in.

How are you measuring the 5 gallons in the fermentor? Also are you putting everything from the kettle in to the fermentor?
Also I noticed that your temperature is in centigrade, some of your measurements are in pounds, some in grams. Are you measuring your water for a US gallon or an Imperial gallon?
A US gallon has 3.785 litres,
an Imperial gallon is 4.546 litres about 20% more
I'm just thinking you are having some kind of volume measurement problem, this is about all I can come with, Good Luck!

 

[vrstud]

Yup, I am a Canuck so I am stuck with British, Metric and American measurements to deal with. I am more familiar with metric but I can use imperial. I have bucket that is marked in quarts. 8 quarts to 2 US gallons (just under 8L) I have measured and marked out both my carboys and pale for easy reference. I have a 5gal and a 6.5 gal carboy. Pretty sure I got my volume correct.

As for mixing the wort, I place the carboy on its side on my lap while sitting down and raise and lower one knee at a time for a couple of minutes. This really mixes up the wort after I have topped it up to the final volume. It's hard to believe that it still wasn't mixed well.

I'm brewing again this weekend and I'll make sure to mix it really well and keep checking the measurements.

 

[eluterio]

To help with mixing the wort and help with chilling faster I take the remaining 2.5 or 3 gallons of water and put it in the refrigerator to help chill it down. I then dump the chilled wort on top of the water to help with the mixing. I used buckets and had a spigot to draw from. I usually hit my marks for my gravity. You may also want to try and boil full volume if you have a big enough container and a method to chill down ie immersion chiller. This will take a lot of the headaches out cause you can get your reading.

Ive read elsewhere that some extract LME if stored there for ever will not have enough sugars to hit your gravity. Try using Dry Malt extract for your next back. The process for DME provides a better shelf life and you might hit your numbers then. If your gravity come out low again using DME there is something else going.

 

[vrstud]

Brewed last night and got my expected OG. Mixed well in a pale.
My faith in LME is renewed.

 

[vrstud]

Brewed again last night using the same process and again hit relatively close to my expected OG 1058 vs 1063.

 

[Qhrumphf]

Well sounds like you're off to the races then. Glad it's worked out for you.