# Crystals, FG and beersmith #noob



## a1149913 (24/11/14)

Hey guys, its probably a massive noob question but i'm struggling to get my head around something i thought i have understood for years!

For the most part, final gravity is determined by the mash temperature, where high temps = more unfermentables and higher FG. Low temps = more fermentables and lower FG.

Crystals have some undermentable sugars due to roasting process and add different flavour depending on roasting temp including sweetness. My understanding is you don't want to use much more than 10-15% as you'll end up with too much sweetness?

If you compare a beer A which is for example 100% base malt OG 1.050 FG 1.010 to beer B which is 90% base malt and 10% crystal OG 1.050 - will the FG be the same as beer A if mashed at the same temperature/same yeast attenuation?

If yes, do crystals add perceived sweetness which isn't measured by FG?
If no, crystals increase FG, how does beersmith work out the FG when using crystal?

Thanks


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## indica86 (24/11/14)

FG with crystals will be higher, all things being equal.
BS has attenuation rates for yeast and also expected sugar levels from grain at whatever temperature the mash was at.


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## danestead (24/11/14)

A guy on an american home brew forum did some fairly extensive tests on the fermentability of various different crystal malts. The fermentability ended up at about 38% for all but the lightest of light crystals. 38% is about half the normal 75ish % fermentability you get from a base malt.


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## verysupple (24/11/14)

Here's an experiment investigating the effect of crystal malt on fermentability.

Interestingly, it shows that if you mash the crystal malt with base malt the yeild is increased significantly compared to steeping it by itself.

It shows that the decrease in attenuation for a 50 % crystal malt grain bill is quite noticeable, but it would be fairly small for a 10 - 15 % crystal malt grain bill - probably a couple of points different for the FG.


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## a1149913 (24/11/14)

Ok so i guess from that experiment, if you're only using 5-10ish% crystal in your mash, you might only see a slight slight increase in FG compared with just base malt. 

So really one of the main reason for not over using crystal is because you dont want to impart too much crystal flavour, rather than the increase in FG you get?


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## danestead (24/11/14)

Jacob Thomas said:


> Ok so i guess from that experiment, if you're only using 5-10ish% crystal in your mash, you might only see a slight slight increase in FG compared with just base malt.
> 
> So really one of the main reason for not over using crystal is because you dont want to impart too much crystal flavour, rather than the increase in FG you get?


Yep normal amounts should only add 1 or 2 pts to your fg.

Correct.


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