2nd BIAB - poor effeciency

[philmud]

Hmmm forget my advice. I BIAB an APA yesterday & ended up with 65% efficiency and a shitload more boil-off than I'd anticipated - that's not to say that regular stirring is a bad idea (Geoff at G&G emphasized its importance a number of times during the demo I watched), but I certainly didn't get the figures I did last time.

Edit: my efficiency was measured taking boil off into account.

 

[GalBrew]

Hmmm forget my advice. I BIAB an APA yesterday & ended up with 65% efficiency and a shitload more boil-off than I'd anticipated - that's not to say that regular stirring is a bad idea (Geoff at G&G emphasized its importance a number of times during the demo I watched), but I certainly didn't get the figures I did last time.
Edit: my efficiency was measured taking boil off into account.

Then your mash efficiency mut have been quite low for that brew if you are getting 65% post-boil.

 

[philmud]

Sorry, to clarify, it's not 65% post boil. It's 65% allowing/adjusting for the additional evaporation.
So actual efficiency was 65% - was a bit over 75% last time

 

[wbosher]

Better than my last one. Went from a pretty consistent 70ish over my last few brews, down to 50% Bad crush at LHBS. To top it off, I think I got an infection as well...tastes bloody awful.

 

[philmud]

Yeah, I gotta say, I wonder if the crush was the issue yesterday

 

[wbosher]

The thing that really gets me is that I KNEW it was a bad crush as soon as I saw it, yet did it anyway. I didn't have too many options though because from memory I think it was ANZAC day, so no one was open to crush it for me, and my little grinder that I used to use had died a horrible death. Probably should have just waited until the next weekend...ya live and learn...

 

[manticle]

Shorter mash times may be acceptable for lower mash temps rather than higher as you suggest.

Actually other way.

However that shorter mash at the high temp will leave a dextrinous beer so is obviously not going to work so well with many styles that require less 'fullness'. Beta can continue to break down the dextrins produced by alpha if given time and opportunity.

Nice little summary of enzymatic behaviour here:http://braukaiser.com/wiki/index.php?title=The_Theory_of_Mashing

I think it's as much to do with gelatinisation temperatures as anything else but would need to check. Interesting bit in the article suggesting how doughing in at lower temps and/or decocting aids fermentability.

 

[bum]

Hmm, that's different from how I recall the frequent discussion one user keeps generating in regards to mashing low and fast for certain more tasteless styles usually going. Perhaps it was something similar to your last point that had me thinking that way?

Thanks for the correction and link. Reading it now.

 

[Kudzu]

Brewed again on the weekend. Decided I'd be scientific and change one thing at a time mash wise for the next few brews to see what makes a difference.

This brew I did everything the same as Brew 2 from the OP but heated water to strike temp before dough-in instead of doing the escalator mash thing. Was a bit off on the strike temp though. I measured the temp at 13C by sticking a thermometer into the crushed grain. according to Brewmate strike temp needed to be 69C for a 66C mash, but the temp only dropped 1C so ended up mashing at 68C

No real change in efficiency, ended up with 1.045 with 20l in the fermenter. Next brew I'll include a mash-out.

I'm trying to work on my post boil volume by dialing back the boil rather than adding more water as I'm losing upwards of 15% to evaporation at the moment.

 

[andy@67]

G'day all,

Geoff and Dan at the G & G demos have inspired me to give BIAB a go. So over the last month I have assembled some gear and did my first AG BIAB today.
I milled my grain twice first at credit card thickness then at hacksaw blade thickness.
I did Dr Smurto's Golden Ale. Overshot strike temp by 2C so removed 3L of strike water and replaced it with cold water, then heated back to strike temp. Mashed in temp was 65.6C aiming for 66C so all good. Mashed for 60 minutes ramped temp to 78C then removed bag and gave it a really good squeeze (I may need to invest in some gloves it was bloody hot). Pre boil gravity was at 1.038 which according to Brewmate is about 79%. Although I may need to find a better sample tube for my hydrometer as the plastic one got decidedly wobbly with the hot wort in it.
Boiled for 60 minutes with 20 grams Amarillo then another 20 grams in the cube (no chill) and I will dry hop another 20 grams. I underestimated loss to trub by 2 L and only ended up with 19L into the cube (live and learn I will allow more next time). Took 3.5 hours in total including clean up.

I lose upwards of 25% in the boil but I have a big pot (80L) so a lot of surface area. I think you should just allow for the boil off with additional water. If you try to dial your boil back too much you run the risk of not boiling off some of the off flavours and not getting the best from your hops. If you want you could float a cake tin in the wort during the boil, this cuts down the surface area and reduces the evaporation slightly for the same boil vigour.

Regards Andrew.

 

[slash22000]

Are you aware hydrometer readings change wildly with temperature? Was the hydrometer reading taken at your calibrated temperature, or at 70+ degrees? Have you calibrated it at room temperature before?

 

[Liam_snorkel]

Nice one Andrew.
A couple of tips:
try using two large frying pan lids to squeeze the bag.
Put the sample wort in a saucepan to cool down a bit before pouring it into the sample tube.

 

[slash22000]

Are you aware hydrometer readings change wildly with temperature? Was the hydrometer reading taken at your calibrated temperature, or at 70+ degrees? Have you calibrated it at room temperature before?

 

[andy@67]

Thanks guys,

I hd not thought of two pot lids to squeeze the bag, but I like it.

The reading was taken at 20C. It started out at about 1.019 when hot, I suppose I could've run it through a calculator to adjust it, but I just waited for it to cool down.

Regards Andrew.

 

[slash22000]

I bought some $20 silicone oven mits from Big W. They're pure gold for squeezing BIAB bags, and taking trays of lasagne out of the oven!