Okay, this was bugging me so I've been emailing back and forth with the distillery, and here is some more info.
They do, in fact, cold "mash" their pre-distillate liquor (not sure what it's called...not wort) by adding amylase to the corn and letting it sit at room temp for an extended period of time. And no, damian_winter, they don't use a vacuum. In fact, they explained why that wouldn't work if you were doing it to boil at lower temps. It wouldn't really be useful for brewing though, because of a few problems.
First, you have to let the mash sit for a long period of time, which makes it more susceptible to unwanted stuff fermenting your wort. They solve this by adding their yeast while they add their grist, along with a decent amount of beet sugar. The amylase is slowing converting the corn's starches to sugar, and the yeast is converting that to alcohol in the mash. The yeast can convert the beet sugar when their isn't enough sugar from the corn, and that crowds out unwanted yeast.
So it's pretty much a mash and fermentation all in one, because as the starch is converted to sugar, the yeast convert it to alcohol. Meaning you wouldn't be able to do a boil afterward with hops because you'd boil out the alcohol. So while it works for distilling (since you want to boil out the alcohol), it doesn't work for brewing.
It was an interesting thing to look into, and the owner was quite helpful with all my questions, so if you're in the Minneapolis area, think about giving du nord a visit. They have a cocktail room, and they make good drinks. (I won a free drink token on the tour because I knew the requirements needed for a whiskey to be a bourbon, so maybe keep that in mind!)
To end, I'll directly post the emails below. Sorry this is a long post!!!
"I will try to answer your question (pasted below) in "short" form, but if this is not clear, feel free to email me back. Please excuse typos; I had to rattle this off pretty fast (long day). Also, apologies if you are a commercial brewer and all of this is old news, I am assuming you are a home brewer. I added some other du nordies to this response because they may get the same question.
The low hanging fruit/easy question is whether or not amylase can be active at room temperature. The simple answer is yes it can. All forms of amylase are protein strings that have their ideal temperature ranges. The alpha amylase in your saliva breaks down starches at temperatures well below the 145-155F most brewers do their saccharification mashes at; this is in part because the amylase is not meant to do the whole job, so a lower efficiency is acceptable. The strains of amylase (beta and alpha) that brewers are familiar with is most active in the 140F range but that does not mean it is not active at 70-80F--it is just much less efficient. In a brewing set up, efficiency is key: most single infusion mash brewers do not have time on their said and need to convert their sugars in a short time to prevent the introduction of other nasties to their beer. I imagine your saccharification rests are in the 30-90 minute range... In fact, the only way the amylase would not convert a liquid mash is if the proteins had been denatured by too much heat. If you want a real world example, look to a barley farmer. The amylase brewers use is all (or primarily) sourced from barley The barley has these enzymes because it needs to use them to convert starch to sugar to feed the germinating seed. No seed that I am aware of needs to have temps as high as 140f to germinate, but no seed grows so fast that it would need all of its sugar in less than 90 minutes...
Ok, so we know that an amylase can hydrolyze polysaccharides at lower temps by taking a hit to efficiency (works for every seed in nature). But we also know that this set up is not practical for beer production because the process is too slow to produce enough sugar to support yeastie beasties in any numbers sufficient to crowd out the molds and bacteria that would take over. As was explained on the tour, this is the purpose of sugar beet sugar in our process. The sugar infusion eliminates the bad bugs problem by providing all the fuel the yeast need to take over the mash and thus allowing the poor distiller more time.
Let's assume ad arguendo that a brewer was willing to add sugar and deal with the unholy beer such a brew would produce; it still makes no sense to cold cook for beer because the temperatures needed to simply convert the barley, wheat, or rye are so low. The entire purpose of cold cooking is to overcome the fact that most corn will not gelatinize via heat at temps below 180ish so time is used instead of heat where heat is not available. Without gelatinization, hydrolysis cannot occur. The grains brewers work with will gelatinize at temps around 130-140 which happens to be in the same range as the prime saccharification temps for β-amylase; for this reason, many home brewers have no idea of what gelatinization is. If your gelatinization temps are the same as your saccrification temps it is by definition not possible to "cold cook." E.g., our rye whisky is made using the exact same process and temps as our L'Etoile vodka, but the vodka mash is a cold cook process and the rye mash is a standard single infusion mash (the difference: the vodka has corn in it).
Just for fun: your friend's suggestion of a cold boil would be impractical and ineffective. The idea behind cold boiling is to lower the vapor pressure above the liquid to a point equal to or less than the pressure of the liquid thus causing it to boil. The problem here is that cold boiling is just that: boiling. Starches don't gelatinize because they boil, they gelatinze via water+heat or water +time. You could cold boil your grains for hours and they still would be rock hard.
In fairness, you asked two specific questions:
"do you guys just let the mash sit at room temp with some amalase in order to convert the starches to sugars?"
"do you think it would work for brewing?"
My answer: yes and no respectively, for the reasons outlined above.
Keep drinkin' good booze,
And that is all! -Daniel