Ok, so in essence this helps "brewhouse efficiency"
exactly
I thought that all specialty grains had enzymes for activity. I guess I should rephrase: Those Specialty grains that need MASHED to produce sugar have enzymes. Those that do not have enzymes but need to be mashed are considered adjuncts and need to have other grains present. Other specialty grains (roasted malts), have the sugar already converted and therefore do not need to be mashed. I'm sure I can look this up and find a chart. I'm not arguing semantics here. I'm just trying to be sure I understand.
yeah, I later realized I couldv'e been much more clear with this part - and keep in mind I'm relatively new to this myself with only 15 batches completed (9 AG, 2 PM, 4 extract).
Your pretty much right on though. Grains with diastatic power should ideally be mashed - they generally have been malted for less time and are very lightly kilned, and this is why the enzymes are still present. Other "specialty" grains with no DP left have typically been "malted" or otherwise converted further to produce more sugar in the grain including some long chain sugars that are unfermentable (such as crystals and cara-malts). These "specialty" grains can then be kilned to higher temps of varying degrees to generate all of the different caramelized or roasty flavors. The high kilning temps are what kills the enzymes and thus no DP. Because they have been malted to a greater degree, these grains can be crushed and steeped, and will still contribute some sugars to the wort, even without any mashing w/ enzymes.
Adjuncts are generally considered to be anything that isn't malted barley - oats, wheat, rice, and corn are all adjuncts as well as any type of sugar not derived from barley. Typically, these adjuncts rely on the enzymes in the barley to convert their starch when necessary.
At least, that's the way I understand things thus far. If any of the resident HBT experts see anything inaccurate here, please step in and correct me!
You can find a ton more info on this stuff on the internets. I'll refer you to
HowToBrew, chap 12 &13 to get you started.
As far as your last process summary, it looks like you got it down.
One tip I have for sparging is to use 2 pots and essentially do a batch sparge. Fill the second pot with your desired amount of sparge water and heat it to 150-170dF. When the first 50 min are up, just move the grain bag over to the second pot of water. Leave it in there for 5 - 10 minutes to allow some more of the sugars to dissolve out into the liquid, then remove the grain and combine the two worts.
As far as calculating how much extract to add once you've done the mini-mash... yes there are equations to figure it out, but I don't know them off the top of my head nor did I ever use them. I would just add my extract in measured amounts and take hydrometer readings after it's dissolved until I reached my desired gravity. It takes a bit longer, but after a few batches you'll get a feel for approximately how much extract you will need to add.
Coming around full-circle: The reason I mentioned starch is because the lightly malted/kilned grains will still have a greater amount of starch remaining. That's specifically the reason why they need to be mashed and don't contribute any gravity points unless they are mashed. You'll still get color and flavor from them, but you'll also get all of that unconverted starch too.
Two final notes then I'll shut up:
Try not to exceed 2 quarts water per pound of grain. Too much water is a bad thing when mashing - not only do you dilute the enzymes, but you also run the risk of extracting tannins and astrigent flavors from the grain husks. 1.5 qts/pound would probably be safer. It'll look like a really thick mash, but it's not. As long as there's enough water for all of the grain to be wetted, then your good.
Don't forget that water quality (PH, hardness, mineral content) is important for mashing as well as steeping. light beers need softer water and dark beers need moderately hard water; although this is a gross generalization. Here in WI, most water is from wells, and is excessively hard. If I'm making a pale ale or somthing really light, I usually buy bottled spring water. For dark beers, I usually use 50/50 tap water and dH2O. Don't ask me about water chemistry though, 'cuz I'm still new to that myself.
Most important thing to remember is to have fun. So do it whatever way is most entertaining, fullfilling, and satisfying to you.