Due to time constraints, I need to do a two- to 2-1/2 hour unattended mash, and then return to lauter, etc. I plan to do a single batch sparge. I am looking for a slightly-less fermentable wort for more body, so I theorize that my ideal mash profile is a single-temperature rest at around 156-158°F (69-70°C). However, my non-heated mash tun is going to lose around 15°F (8.3°C) over 2-2.5 hrs., I estimate**. So I need to mash in higher. I don't have the ability to add more strike water mid-mash because I am maxed out on MLT space, and will not be around to do it.
Q1: What sort of wort profile can I expect if I mash-in at 162°F (72°C) , and end up at 147°F (64°C) over 2-2.5 hrs.? John Palmer says in How to Brew that beta-amylase is denatured at 154-162°F (68-72°C), but I have seen other writers say that overnight mashes lead to very fermentable worts and dry beers.
Q2: Does the mash-in temp determine the fermentability of the wort, or is it based on the whole mash?
Q3: Besides buying a new cooler, do you have any advice in terms of tips, techniques, or mashing temps?
In case it matters, this is a partial-mash recipe; 2.5 gallon (9.5 L) batch (fermenter volume). My malt bill is 4.2 lbs. (1.9 kg) of grain (71% Golden Promise, and 23% Belgian Caramunich, 8% 160°L crystal), mashed at 1-1/3 qts./lb (0.57 L/kg), plus 0.75 lbs. (0.34 kg) of DME. Yeast: Danstar Nottingham.
- ** My two-gallon (7.6 L) beverage cooler mash tun loses 10°F (5.6°C) in one hour without a blanket, but I have added insulation to the lid and plan to wrap in a blanket, so I expect a maximum 15°F (8.3°C) loss over 2-2.5 hrs. I do preheat the cooler with 185°F (85°C) water. The lack of thermal mass, and inefficiency of cold beverage coolers to keep contents hot, are drawbacks of small batch brewing. This is the first time I am trying for a less-fermentable wort.