The mysterious case of the diminishing sugar level…..

[Storm Brewing]

Hi All
I wonder if anyone can help me out here but this issue is slowly driving me mad! Today I did a small brew of Bohemian Pilsner (2.5 gallons – all grain), a recipe I have followed before. In order to achieve this volume I had 3 gallons of wort after mash and sparge.
I took a gravity reading with a hydrometer before boil and (temperature adjusted ) the reading was 1.047. This equates to a total 3 x 47 = 141 GRAVITY POINTS. After the boil, I took a second reading and this was (temperature adjusted) 1.046. This equates to only 46 x 2.5 =115 GRAVITY POINTS.
Where did this go and has anybody any similar experience? The hydrometer is 2 years old and from a reputable HB shop, the temp conversion is from the Brewers Friend website. As this has happened before, I took photos of all readings to eliminate the possibility of short term memory loss!!
I wondered if hops absorb sugar from the wort so to mitigate against this, I use a hop spider and sparge its contents with a kettle of boiling water on completion of boil (but maybe should have squeezed the life out of the soggy hops???)
Not much to add really but most grateful for any thoughts / observations/ similar experiences

Cheers

Pete

[MarkA]

Hops don't absorb sugar, so adding a kettle of water is adding to the volume and reducing the SG ie watering it down

[Storm Brewing]

The boil evaporated some of the wort as you would expect - the kettle full of water bought it back to 2.5 gallons

[Jocky]

You said your readings with the hydrometer were temperature adjusted - what temperature did you measure at? If it was hot then there’s every possibility the heat damaged the hydrometer,

Another possibility is that you took a sample from the pre boil wort before it was completely homogenised.

[guypettigrew]

Hi. When you say the gravity was lower after the boil, do you mean you measured the gravity in the kettle before running the wort off?

Or do you mean the gravity dropped after running the wort from the kettle and after you'd sparged and squeezed the hops?

Guy

[Storm Brewing]

Guy, Jocky - thanks for taking the time to reply. I will deal with both observations in one hit to avoid duplication.

To be absolutely clear, i took the first hydrometer reading immediately following the sparge. I extracted a sample and took a reading at 59 degrees C.
My second reading was taken at the very end of the boil -after hops had been sparged (but not squeezed). I let the sample cool before cheching the final gravity.

Your comments are helping me to see possible flaws in my methodology!!

1. The nature of sparging means that early (most dense / sugary) wort falls into the bucket first as i recycle the wort through the grain bed to help with it's clarity. The sparge water (less dense) falls in next. It is entirely possible as Jocky points out that the wort is not fully homogenised (vaguely remember thst concept from school a long long time ago!!!). MEMO TO SELF - give the wort a good stir before taking a gravity reading to avoid misleading readings!!!
2. Squeezing the sparged hops will make sure any sugary wort still absorbed into the hops is released.

Thanks both - you can't beat a fresh pair of eyes!

Pete

[MashBag]

Pete,

For what is worth I think 59c is a bit high IMO. Is it worth cooling the sample for increased accuracy.

A refractometer would also help your cause. £15 you will never regret spending.

[Storm Brewing]

OK Thanks-i'll give it a try. Can you recommend one?

[guypettigrew]

This is as good as any, if you want a hand held one. You'll need to convert the Brix reading to gravity. Plenty of on-line converters available. For a quick 'rough' conversion, multiply the Brix by 4.

If you fancy spending a bit more, then a digital refractometer is worth getting.

Guy

[IPA]

You can also buy one like this that that gives you the wort original gravity as well as Brix.
https://www.amazon.co.uk/AUTOUTLET-Refr ... 71031&th=1
Remember though that it can only be used before fermentation.
Invaluable on a brew day

[guypettigrew]

You can also buy one like this that that gives you the wort original gravity as well as Brix.
https://www.amazon.co.uk/AUTOUTLET-Refr ... 71031&th=1
Remember though that it can only be used before fermentation.
Invaluable on a brew day

Much more user friendly than the one I linked to!! Nice one, IPA.

Guy

[MashBag]

Brix as a scale is pointless if you don't use it, %alc is a nice guide but not essential.

Get the one that reads what you want. Always check the pics for the view on the eyepiece.
I

[Storm Brewing]

Great advice - thank you everyone

[drjim]

I got exactly that digital one and it destroys batteries in about a minute so need to remove them every use. I've gone back to a hydrometer (two actually). Did wonder if it was cheap AA batteries failing, we had a big boxful of them, it's somewhere in the shed now so I'd have to find it and try it with some better batteries, but as it stands I'm not impressed with it.