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Old 09-29-2008, 09:24 PM   #1
Shawn Hargreaves
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Default Unexpectedly high starting gravity

I did my third partial mash brew yesterday (after many successful extract brews) and all seems good, except my starting gravity was much higher than expected.

Here's my recipe:

Type: Partial Mash
Batch Size: 5.00 gal
Boil Size: 3.50 gal
Boil Time: 60 min

Mash for 70 mins @ 150
2.50 lb Munich Malt
1.00 lb Wheat Malt
0.25 lb Acid Malt

Late addition (10 mins)
4.00 lb Light Dry Extract
1.00 lb Jaggery

Hops
0.50 oz Northern Brewer [7.40 %] (60 min)
0.50 oz Sterling [7.00 %] (30 min)
0.50 oz Goldings [4.10 %] (30 min)
0.50 oz Sterling [7.00 %] (5 min)
0.50 oz Goldings [4.10 %] (5 min)

Spices
1.00 items Orange Peel (Boil 5.0 min)
0.25 items Grapefruit Peel (Boil 5.0 min)
0.75 oz Coriander (Boil 5.0 min)
2.00 items Star Anise (Boil 5.0 min)

1 Pkgs Belgian Ale (White Labs #WLP550)


My two previous partial mash brews both ended up with 60% efficiency. I tweaked my sparge process a little this time in an attempt to improve that, but was expecting at most say a 10% boost.

But here's the thing - with 60% efficiency, BeerSmith predicted an SG of 1.060, but I ended up with 1.073!

How can this be? I'm not particularly worried about it (I'm sure the beer will still be good, if a little stronger than expected) but I'd like to understand what happened here.

Some things I considered:

- Bad gravity measurement? But I repeated this a second time, and got the exact same figure both times. Wort temperature was bang on 60 when I sampled it.

- My mash efficiency somehow went through the roof? I don't see how that could account for it, though: BeerSmith reckons I would only get 1.071 SG even if I somehow hit 100% efficiency!

- Bad measurement on some of the ingredients? The only one I can imagine getting my quantities wrong on here is the jaggery. But to explain that gravity, I would have had to use more than twice as much as intended. I don't see how I could have gotten that so far out.

Any other explanations I'm missing?


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Old 09-29-2008, 11:30 PM   #2
bull
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i think maybe it has somthing to do with the 4 lbs. of dme.but hey ,im new at this too


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Old 09-29-2008, 11:34 PM   #3
Shawn Hargreaves
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DME is DME, though, right? Is there really that much variation in how much gravity you get from a given amount of extract?
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Old 09-29-2008, 11:57 PM   #4
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Perhaps you didn't collect as much wort overall and have less of a more-concentrated wort?
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Old 09-30-2008, 12:38 PM   #5
carl spakler
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My guess is for a poor sample of the wort, my OGs are quite often far off what they should be on the high side. I know that there is no magic in my kitchen that pulls more sugars than is possible.

Perhaps pull a sample and let it sit for an hour or two, then pour off the top with as little sediment as possible and take the reading. I started doing this and have been getting readings in line with what I expect based on brewing software.


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