A funny thing happened on the way to the brew kettle

[Pilgrim]

I normally do 60 minute mashes and always do a starch check at 50 minutes. Allways get complete conversion at 50 but do the extra 10 anyway. Today I checked at 50 and the resultant wort went as black as the inside of a cow's guts at midnight on a moonless night. So I checked again at 60 and the same. After 90 minutes it was still showing signs of grey and I was only happy that it was clear after 120 minutes.

Grain Bill was:
3.8 Kg Global Kolsch
2 Kg Global Pilsen
200 gr Wheat Malt

Wort pH was around 5.2 and Mash temperature was 68 deg. C. OG was 1.056

BeerSmith calculated my efficiency at 80.72% so I,m happy with that.

Questions are:
1) why did it take so long to achieve full conversion?
2) will the extra mash time have any adverse affect on the final taste?

[denimglen]

1 - I'd say it probably didn't. With a grist like that all the malts have diastatic power, your pH was spot on and at 68C it should have converted quickly. Maybe just some starchy bits that hadn't been wetted down fully? Most mashes will fully convert in about 15 - 20 minutes, so I don't mash over 30 minutes now.

2 - It should be fine. If there was a temperature drop over the rest it will probably just ferment out a little more.

[Pilgrim]

Maybe just some starchy bits that hadn't been wetted down fully?
Don't think so. I gave it a good stir after the 50 minute test so should have been ok at 60 minutes.
Thanks for the suggestions though Glen.

[James P]

so I don't mash over 30 minutes now.

Do you notice any difference in efficiency, or extract at all?

[denimglen]

Nah bro, no difference in efficiency. That was actually how I decided to stop mashing the full hour. A couple times at 30 minutes I took a refractometer reading and I was at 98% conversion - which is what I usually get.

And now my attenuation is more in-line with my mash temp, because of the temp loss over that last 30 minutes and I've knocked 30 minutes off my brew day.

I'd probably still mash 60 mins for anything over 1.080 or something I want to REALLY dry out.

[James P]

Cheers DG, I'll have to give it a try, but not for the lagers.... :)

[Stu McKinlay]

A good overview here:
http://www.howtobrew.com/section3/chapter14-6.html

Zymurgy did a great article on mashing about 3 years ago. I can't remember who it was but it may have been George Fix (it was certainly at the back of the mag in the techy section). I could be wrong but, from what I remember, all their mashes had reached full conversion by about 30min. I think some were around 20min.

[denimglen]

Yeah there was a similar question in BYO once, coming to the same conclusion IIRC.

[warra48]

30 minutes!
Makes my last 2 hour mash of an IPA look positively painstakingly long by comparison.
The reason I did it is that the bulk of my grist was floor malted Maris Otter. It's an old fashioned grain, and I think a 1½ to 2 hour mash is more in line with what the Brit brewers of old used to do. Got 96% mash efficiency. WY1968 is chewing through it steadily.