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-   -   Help me lower my FG's.... (http://www.homebrewtalk.com/f13/help-me-lower-my-fgs-4985/)

StudentBrewer 01-14-2006 07:38 AM

Help me lower my FG's....
 
In preparing for brewing my first higher gravity (extract/grains) brew, I would have been reviewing all my brewing books and all the online material regarding ways to ensure a full furment. It seems that most of my normal gravity brews hang up between 1.015-1.022, which seems slightly high (according to my limited knowledge). I am not currently using an aeration stone for oxygenation. I primarily use US-56 dry yeast, but have otherwise been using white labs with a starter. Any ideas? Please fire off any and all pointers which may help lower my final gravity.

StudentBrewer 01-14-2006 04:40 PM

Sorry, I just realized that I posted this in the wrong forum. Meant for it to be under general techniques. Oops. :drunk:

El Pistolero 01-14-2006 05:37 PM

I moved it for you.

Beer Snob 01-14-2006 07:12 PM

Realy depends on several things...

What recipe are you using? If you have unfermentables for instance, your FG will be higher....

How are you brewing this recipe? Extract...? Are you seeping grains? AG..... ? I am reading Palmers book on AG mashes (something I have not done yet) and he is describing changes in the process itself (like the temperature.... rest times...) will change fermentables, hence change your FG.

Tell us a little more about what you are doing:)

drengel 01-16-2006 11:27 PM

best way to ensure full fermentation is proper yeast pitching rates AND oxygenation. if you don't pitch enough yeast all the stored energy from oxygen will be used multiplying rather than fermenting. an aeration system is nice, but not totally necesray. really concentrate on aerating that wort next time. shake it, pur it between buckets, whatever you want, just try as hard as you can to get o2 in there. if your still having problems then try a aeration system, theyre not too expensive. but the key is pitching enough. there is an article i read a couple months ago off of a post in here abbout yeast starters that is on the maltose falcons homebrew club website, it was very informative and fully convinced me that my high FG woes were a product of underpitching. since then my FG's have been around 1.010-12. i would recomend looking that up and reading it.

Alvin 01-21-2006 06:12 AM

Help me lower my FG's
 
FG is determined by the fermentability of the wort. Try mashing at 145 deg. F and extend the mashing time to 90 - 120 minutes. I have achieved FG's of as low as 1.002 in the secondary fermentation making a Kolschy Brew using this technique.
Two enzymes are responsible for most of the conversion of starch to sugar. Beta-amylase works at a lower temperature (140 - 150 deg. F) and attacks the end of a starch molecule producing a Carbon-6 fermentable sugar molecule each time it operates.
Alpha-amylase works at a higher temperature (150 - 160 deg. F) and randomly attacks the middle of a starch molecule producing a C-6 fermentable sugar each time it operates also, but the remaining starch fragments are not necessarily a multiple of C-6, and after several fermentable sugar molecules have been severed from the starch chain there remains starch fragments (dextrins) that are C-3, C-4 and C-5 which are not fermentable.
The higher the conversion temperature, the faster the conversion occurs and the greater the amount of unfermentable dextrins. Extract manufacturers want to complete their conversion as fast as possible for economical reasons and most extracts are very dextrinous leading to high final gravities.
All grain brewing gives the hobby brewer better control of the mashing process to end up with a very fermentable wort for such styles as Kolsch.

Alvin 01-21-2006 06:46 AM

Help me lower my FG's
 
FG is determined by the fermentability of the wort. Try mashing at 145 deg. F and extend the mashing time to 90 - 120 minutes. I have achieved FG's of as low as 1.002 in the secondary fermentation making a Kolschy Brew using this technique.
Two enzymes are responsible for most of the conversion of starch to sugar. Beta-amylase works at a lower temperature (140 - 150 deg. F) and attacks the end of a starch molecule producing a Carbon-6 fermentable sugar molecule each time it operates.
Alpha-amylase works at a higher temperature (150 - 160 deg. F) and randomly attacks the middle of a starch molecule producing a C-6 fermentable sugar each time it operates also, but the remaining starch fragments are not necessarily a multiple of C-6, and after several fermentable sugar molecules have been severed from the starch chain there remains starch fragments (dextrins) that are C-3, C-4 and C-5 which are not fermentable.
The higher the conversion temperature, the faster the conversion occurs and the greater the amount of unfermentable dextrins. Extract manufacturers want to complete their conversion as fast as possible for economical reasons and most extracts are very dextrinous leading to high final gravities.
All grain brewing gives the hobby brewer better control of the mashing process to end up with a very fermentable wort for such styles as Kolsch.


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