Mashing Technique

It sounds like you're doing BIAB, which I've never done, but I would say:

1) I wouldn't think you would risk scorching the bag by putting it in at a lower temperature than you eventually planned to reach, but yes, you will get some enzyme activity at that lower temperature that *might* have undesired effects. Most likely, the worst that would happen is that your beer would be drier than you planned for, so it's probably not a big deal as far as that goes.

2) Correct. You definitely want to stir at the beginning of the mash to make sure your grain is completely saturated, and it's a good idea to stir about every 15-20 minutes just to makes sure you're not getting hot and cold spots or clumps that are too dry for maximum conversion.

I can't think of any benefit from not stirring. But there is a whole procedure known as step mashing in which the grains are put through a series of progressively warmer rests which some people swear by. This is usually considered unnecessary with most modern base malts, but in previous eras it helped to achieve better conversion from less well-modified malts. Some still do this for the sake of tradition (as step mashing is traditional for a number of german beer styles) and some believe you can get certain specific benefits (ie, more clove flavor in wheat beer) by resting at certain temps. It's a fun thing to experiment with, if you have the time and equipment to do so. Otherwise, a single infusion mash at one specific temperature is the usual way to go.

 

Bringing the mash up through multiple temps is not that big of a deal as long as you continue upwards towards your target temp without stopping for any length of time.

However, not stirring a mash thats sitting on direct heat is definitely an issue. Dough balls are a problem, and you're also not distributing the heat throughout the mash, in other words the temp at the bottom of your kettle is going to be much higher than the temp at the top. Also, I have seen nylon bags melt from this, and that is no bueno.

What was your extraction efficiency?

 

On my last batch I thought I could get away with running some errands during the mash and only stirred at the beginning and end, skipping my mid mash stir. I paid for it in efficiency. Some food for thought...

 

If you did a proper job of stirring as you dough in you shouldn't have to stir again during your mash. You'd stir between batch sparges thereafter.

Edit: Doughing in usually takes about 5-7 minutes for me. I start with water that +14F above my desired mash temp. It takes at least 4 or 5 minutes for the mash to stabilize in temp, so I just spend that time stirring and breaking up dough balls.

 

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I regularly get 80+% efficiency with only stirring before the rest. I do stir with each of my two batch sparges though.

 

Mashing is a pretty forgiving process. If you didn't scorch the grains, all your temperature ramp did was give some enzymes a little longer to break down some of the compounds in the mash - read http://www.howtobrew.com/section3/chapter14-1.html for details. This may help or harm your beer, but either way, the impact is likely to be marginal unless your ramp time was very slow.

Yes, you will have more efficiency if you stir and you will even out the temperature in the mash. I don't use direct heat in my mash so I don't know what a typical temperature differential is for the top and bottom of the mash tun is. I'm sure it is system dependent. If you didn't scorch your grains or melt your bag, I wouldn't worry about this particular beer, but I wouldn't take that risk a second time.