Where did all the sugar go?

[edennis]

I did my first all-grain yesterday. I have done a bunch of extracts and a couple of partial mashes prior. Everything went smoothly I got a 77% efficiency from the mash resulting in 4.85Gallons of 1.065 wort. I poured in some water to bring the total volume to 6.5 Gallons. I started to boil and 70min later after adding all my hops I cooled the 5 gallons of wort to 76 degrees and took a gravity reading. The gravity was 1.052. Did I boil off all that sugar (1.065 to 1.052)? Is this normal?

 

[jdoiv]

The sugar doesn't boil out. What you did do was to dilute your wort when you added the 1.65 gallons of water. You took your pre-addition wort from 1.065 to 1.049 at 6.5 gallons. Then you boiled the 6.5 gallons down to 5 and got your OG of 1.052.

 

[Sir Humpsalot]

And you might have forgotten to cool your wort before taking the measurement. Temperature alters the reading quite significantly.

 

[edennis]

Ok that makes sense. I thought that if I added to water and then boiled it off it would stay roughly the same as my mash gravity and since I was using 11.5 LBS of grain I thought my OG would be a little higher. Oh and I did correct the temp. for the mash gravity. It was 1.050 @134 degrees F = 1.065 if I did my calculation right. The OG gravity was 1.051 @ 76 degrees F = 1.052.

 

[FlyGuy]

Something still isn't quite adding up here. Assuming that your corrected gravity readings are accurate, a change from 4.85 to 5.0 gallons shouldn't have resulted in a drop of SG from 1.065 to 1.052. Are you sure you were able to measure those volumes accurately?

 

[edennis]

Ya, I used my hydrometer for both. The only thing I can think of is I measured the mash gravity from a valve close to the bottom of a bucket (TrueBru 7Gallon buckets) and the OG I measured after pouring half into the fermenter, stirred, and measuring from the top of my 10Gallon pot. I don't know if that would have any effect on the readings. As far as the volume go my TruBru bucket has .5 Gallon increments on the side and the mash wort was slightly below 5gallons(about 4.85). My boiled wort, once I poured it into the fermenter it was almost exactly at 5 gallons (maybe 5.1Gallons).

 

[FlyGuy]

If this was an extract batch and you took your first SG reading from wort drawn from the bottom of the kettle, I could see that kind of difference possibly occurring. But I would have thought that your total runnings from an AG batch would have been more consistent than that. But depending on how your lautered your mash, perhaps the high gravity runnings that you collected first simply stayed at the bottom of the bucket. I suppose that's feasible.

I guess you can 'test the hypothesis' next time by giving that wort a good stir to mix things together in the boil kettle first thing, and then take a reading.

 

[edennis]

That's probably what's going on. I guess I'll have to make another batch soon to test this theory, oh darn
Thanks everyone for the help.

 

[Bobby_M]

First runnings are high OG and reduce from there. It's very likely you pulled a higher than average OG from the bottom. It wouldn't take much stratification get the results you're setting.