Bad Mash process?

Hi, I recently did my first 'all grain' using the Brew in a Bag method. I felt that it all went well but the fermentation process seems to have stalled. I took a gravity reading and it had dropped some but not close to where it should have. I know the air lock isn't a good gauge but there just isn't any activity in the glass carboy that I can see, and originally there was some mild activity.

I've since added more yeast and it didn't do anything, so my guess is that I didn't extract sugars from the grain very well and that it just was a short ferment because there wasn't much to ferment. I know that the target temperature for the Mash is around 152-154 for my grains but how far above that would I have had to be for it to stall like this?

I've read that being to hot will reduce the amount of fermentable sugar. My thermometer indicated that I was very stable around 154 but I no longer trust this thermometer.

Any ideas? I just want to avoid having this happen again.

Thank you all!

How long did you mash? What type of yeast? How long since pitching? What's ferment temp?

Might consider rousing yeast a bit by shaking fermenter.

If you get above 160 then you are too hot.

beerman0001 said:

If you get above 160 then you are too hot.

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For a 75 minute mash, how long above 160 would it take to ruin it?

BrightSpot said:

How long did you mash? What type of yeast? How long since pitching? What's ferment temp?

Might consider rousing yeast a bit by shaking fermenter.

Click to expand...

75 minute mash. Steady 66 degree ferment. I tried shaking but it didn't do the trick. After a short time I decided that I cared more to figure out what went wrong more than trying to save the small batch. I added sugar and got some action. So it's just not a very fermentable mash I guess. I had a ton of trub in my fermenter. I think the mesh bag I had is too coarse. I shouldn't have listened to the brew shop guy.

spikor said:

For a 75 minute mash, how long above 160 would it take to ruin it?

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If you hit 160 in the first 30min of the mash then it is a done deal. After that it all depends on your grains.

beerman0001 said:

If you hit 160 in the first 30min of the mash then it is a done deal. After that it all depends on your grains.

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that's surprising to me because strike water temp is above that, not that I doubt you one bit. I am a newbie and I'm trying to make sense of everything. For me, the temp hasn't dropped as much as people have suggested it would. The first time I struck at around 164, and it just seemed to sit there. I got it cool as quick as I could but it took a while to drop down to 154~.

I did a second batch using this method yesterday. I didn't strike until the temp was down to around 160. Even still it seemed to sit there after I added the grain. I stirred and aerated to help chill for 10 minutes until it was down to 154.

I hope this one goes better! Thanks for your help!

I get a 12 deg drop in temp when I add my grains to the strike water. So if I want 152 mash temp I strike at 164. The drop in temp happens as soon as all the grain is dumped in to the mash tun so it is not really ever at the higher temp.

What are you mashing in? And are you using a water calculator?

What was your recipe? If it was something crazy with several pounds of crystal or if you used a lot of adjuncts with a base malt with lower diastic power it could of been an issue.