Mash temperature and lenght

[Jeltz]

I've been reading mentions of overnight mashing and the heat loss during that time.

I assume that the majority of the efficiency is achieved within the 1st 90 minutes and that anything longer is just trying to squeeze the last few percentage out but is it possible to mash for too long and what are the ramifications to the starting and finishing temperatures of a mash?

I ask as it seems to me that getting the water up to temperature at say 11PM and starting a mash then getting the boil on around mid morning the following day would suite my schedules better than a whole day's brewing.

 

[graysalchemy]

When I did my overnight mashes last week I mashed them at exactly the temp I wanted ie 66c. However what i did do is make sure the mash was fully mixed an the temp was taken from right in the middle of the mash. Because of all the faffing i had to add quite a bit more hot water to get it spot on, so for the second one I did I aimed higher and then corrected it with a little cold water. It is easier to drop the temp than raise it (believe me I have had that problem before and had to use a steam cleaner to raise the temp.

Make sure you wrap your tun up well My insulated tun was wrapped in 4 blankets but I also put foil over the surface of the mash and filled the dead space with bubble wrap. The first mash I did I lost 13c and the second one i lost 10c. I did read that you have to make sure that the mash stays above 50c to stay sterile how true this is I don't know. But my mashes lasted 15 hrs and where fine.

You will most likely get increased efficiency which did cause a bit of a problem as my bitter is not as bitter as I would have liked as a result, (higher gravity beers need more bittering to achieve the same perceived bitterness).

Overnight mashes certainly makes brew day quicker I shaved about 3 hrs off my normal day and if I had used a timer on the HLT then this would have saved at least another hour.

Definately worth it IMHO :thumb:

 

[Jeltz]

That's great,

Regarding the keeping over 50C, if its boiled after does it matter if its not quite 100% sterile anyway.

 

[graysalchemy]

I read that spoiling can take place and produce off flavours, but as i said how true this is I don't know.

I would say that if I managed to keep it above 50c with a 15 hr mash I would have thought you should easily keep it above 50 with a shorter mash time. Most people only leave it for about 8-9 hrs, it is only because of my secret brewing within work hours that I left it for so long. :thumb: