Why is my O.G. less then what I calculated?

Question

I am trying to figure out what I did wrong, when I measured my O.G. it came out to 1.060/1.062, what i calculated is, and what the recipe states it should be in the 1.070 to 1.080 range......

recipe:

Brewers Best: Double IPA - Imperial IPA (14C)

Boil Size: 4.00 gal

Boil Time: 60.000 min

Efficiency: 70%

OG: 1.076

FG: 1.019

ABV: 7.4%

Bitterness: 70.6 IBUs (Tinseth)

Fermentables

                Name    Type   Amount 

Briess LME - Golden Light Extract 9.900 lb

Corn Sugar (Dextrose) Sugar 1.000 lb

Caramel/Crystal Malt - 40L Grain 8.000 oz

Cara-Pils/Dextrine Grain 8.000 oz

Total grain: 11.900 lb

My Procedure

1. Fill Pot with 3.5 Gal water
2. Heat, water and add LME and Corn sugar
3. Steep grains/mash in other pot, with 1 Qt water, 30mins @155F
4. Sparge with 1 Qt water 170F - 180F, add to brew pot
5. Start Boil, and follow brew instructions, boil-->add hops,last 15 add hops, last min, add hops....
6. cool wort to 68F/70F
7. put into primary and top up to 5Gals, take S.G.
8. Aerate and Pitch Yeast
9. Have a Home Brew.

The only change i have made to my procedure from last batch to this batch is how i transfered over to the primary. My original is dump the entire batch into my primary with a fine screen colander, compared to (this one) siphoning to my primary. after the siphoning i Had about .5 inches of trub/hops/and stuff at the bottom with a thin layer of liquid, probably about 1/2 cups worth.

What caused this loss of .010 to my brew and could I make this up in the secondary, by adding boiled DME/wort to it?

Also Bonus question, what effect will this have on it, since this no longer in the imperial range.....?

right now it seems like its ok, and the wort tasted sweetish and hoppy, but could not compare to my first 2 (dry stout, Irish red ale)

Answer 1

Did you do a partial boil and add more water afterward? If so, the problem is likely to be inadequate mixing. The wort is heavier than water so when you take a reading you get essentially "watered down" wort. It's nearly impossible to get them mixed thoroughly to get an accurate reading. But if you use all the ingredients and end up with the volume the recipe specifies, you WILL hit the predicted OG.

Answer 2

If the volumes are as you both computed and experienced, then there's not very much reason why an extract brew would be so far off the OG number. My guess is that the computer added in the results of "mashing" the crystal grains, crystal does not have any diastatic power. Without any base malt present, no converstion can take place. So your "mash" was really a "steep". At the same time, crystal (by definition) does contain already-converted and caramelized sugars that don't need to be mashed at all, so you still got that fraction of the sugars just from steeping.

But, if we assume a pound of crystal is good for about 1.036 in 1 gl of water (point per pound per gallon, or ppg), and 50% that is in convertable starch … that's 36 ppg * 50% (crystal) / 5 gl = 3.6 points … or more like a difference of 1.004 for the 5gl batch, not 1.010.

Another source of error/difference might be hydrometer temperature correction? Was your wort still warm/hot when you took the hydrometer reading? Did you correct for temperature?

The biggest effect is simply going to be a bit less alcohol. You'll still have the higher OG and body from the unfermentable sugars from the crystal. You'll have slightly higher hop utilization and bitterness. I don't think it'll have a huge impact, tbh.