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LME Strength / Potency Testing

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gwhite94621

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I am on my second time brewing a Scottish strong ale and each time my OG has been much lower than I expected. I am hoping someone can give me a little advice on what may be going wrong.

Here is my recipe: https://www.brewtoad.com/recipes/scottish-ale-97ed79

First round was a 1 gallon batch, second round was a 5 and I've double checked that I scaled everything up properly. As you can see BrewToad estimates an OG of 1.097, my OGs have been 1.048 and 1.05

Given the recipe seems built with plenty of fermentables, I am wondering if there is a problem in either my extraction, or my source.

Is there an easy way to verify the the liquid malt extract I am purchasing has the levels of sugars it ought to?
 

MaxStout

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Shouldn't be an extraction issue, as that was done by the mfr. I cannot think of a reason you would get half the predicted OG, unless your brew store is selling you watered-down LME.
 

day_trippr

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The LME alone should have gotten the OG 2/3rds of the way to 97 points.
Usually these things turn out to be insufficiently mixing in topping-up water...

Cheers!
 

ajdelange

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Is there an easy way to verify the the liquid malt extract I am purchasing has the levels of sugars it ought to?
Yes. Add 900 grams of water to 100 grams of the syrup. Make sure the syrup is thoroughly dissolved and measure the SG using the Plato scale on the hydrometer (or use the SG scale and convert to Plato). The Plato reading is the percent of sugar dissolved in the solution by weight. If the mix reads 9 °P then there are 90 grams of sugar dissolved (because your mix is 900 + 100 grams) and there were 90 grams in the syrup which is apparently 90% sugar w/w. If it reads 8 °P then it is 80% w/w. I have no idea what the sugar content should be.
 
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gwhite94621

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Yes. Add 900 grams of water to 100 grams of the syrup. Make sure the syrup is thoroughly dissolved and measure the SG using the Plato scale on the hydrometer (or use the SG scale and convert to Plato). The Plato reading is the percent of sugar dissolved in the solution by weight. If the mix reads 9 °P then there are 90 grams of sugar dissolved (because your mix is 900 + 100 grams) and there were 90 grams in the syrup which is apparently 90% sugar w/w. If it reads 8 °P then it is 80% w/w. I have no idea what the sugar content should be.
Thanks for this, I will definitely give that a try and see what my results are. Like you said, figuring out what the target should be is going to be the hard part.
 
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gwhite94621

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The LME alone should have gotten the OG 2/3rds of the way to 97 points.
Usually these things turn out to be insufficiently mixing in topping-up water...

Cheers!
Assuming all the ingredients were correct, that was the only thing I could come up with too (and for the same reason). It is the most logical reason, which makes me think it's likely the correct conclusion.

I brewed this one at a friend's house on his cement porch, and my primary was a glass carboy, so I didn't rock it like I normally do. I did drive the carboy home buckled up in my backseat, so I thought that 15 minute ride would've moved things around adequately, but maybe not.

It'll be interesting to see how things look once fermentation gets started
 
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