Let's say I mash in at 65 C and over an hour it drops to 60 C - will this have a detrimental effect on my brew?

  • What material is your mash tun made from? My cooler only loses 1-3 F over a similar time span.
    – baka
    Commented May 19, 2012 at 15:09

2 Answers 2


The bulk of the starch-sugar conversion happens in the first 15 minutes of the mash, so that's probably not a big problem. You might need to mash for 90-120 minutes rather than 60 to get a really good, full conversion, though.

I usually have to do a longer mash when I'm mashing "cool" (which you are), anyway.

  • Agreed on the time. At that temp conversion takes longer.
    – Denny Conn
    Commented May 19, 2012 at 18:38

I have experimented with a couple overnight mashes. I mash in and hit my 154F mash temp, close the cooler and wrap it in few heavy towels and an old sleeping bag. I know that normally my cooler holds the 152-154F temp for at least 60minutes. So I am not worrying about conversion time. But in the morning my mash may be at 135F.

So to address flavor concerns there aren't any that I have noticed with a cooling mash. Conversion in your case is still a concern as you mashed in cool and lost temp pretty quickly. Outside of conversion, I wouldn't worry about flavor issues.

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