F.G. why do you tourment me.

[jzelina]

On my last all gran batch, I tried beirmunchers octoberfast. I had been running low on my gravity so I adjusted the recipe to 60 percent efficiency. I mashed for for 75 minutes stirred several times during mash to try to drop temp. , iodine test showed conversion done at that time. Temp may have been a bit high. Around 160. I expected a couple of degree drop in mash tun that did not happen. First running's came in 1.070. after boil 1.076. so about 20 points higher than it should. three previous beers came in 8 to 10 points low. I mashed at lower temps the other times. Does temperature affect how much is converted? I know it affects the type of conversion, or are the different fermentables different gravities? I looked around, but could not fine an answer to that question. Also I had lots of floaties in my sample, Guessing that might push my gravity up a touch. Any input appreciated.

 

[cmoewes]

I mash at 160 is going to favor alpha amylase which will produce more dextrin which aren't fermentable by the brewing yeast. This will lead to a sweeter finished beer with a higher final gravity. Mashing at 140-148 will favor beta-amalayse which will result in shorter chained sugar which are more fermentable. In either case your OG will be the same (sugar is sugar when measuring gravity) but the types of sugar converted will impact final gravity.

I like to refer to this chart from Palmer.

 

[jzelina]

Thanks, I had an good idea about the different temperatures and the Malty/Bitter correlation. The swings in my gravity, I am trying to narrow down, as well as water need. I was at first high on gravity low on wort amount, then low on gravity high on wort amount. Now I went back to high gravity low wort amount. I am really thinking stirring during mash, is the issue. So a little more sparge water with more stirring is next.