You really should do a bit of reading up (google it), its quite a complicated question (along the lines of grandma asking how TV works)
It hasn't the available enzymes of malted wheat, these are produced during malting, the protein and glucan structures that hold the starch granules together haven't been "modified" during malting so they are much harder to get at.
To get the most out of unmalted cereal adjunct (any grain) it needs to be milled, and in many cases or if used at high levels be boiled to break out the starch granules and to make them available to the enzymes from the base malt.
You really should do a step mash, to activate Glucanase and some of the Protease to break down the B-Glucans and Protein, less important if you use Flaked or Torrefied grain.
Also, not all Wheat is created equal, with barley there are special breeds grown for malting and brewing, not the case with Wheat, the most desirable wheat for bread/pasta... is the least useful for brewing, being high in Glucans and Protein. So be careful which wheat you use, brewing quality wheat is nearly as expensive as malted wheat (doesn't make sense on one level, its down to supply and demand)
Any unmalted grain will add a slick creamy mouthfeel to the beer, it will also make the beer cloudy.
You (as above) need to do some more reading, and probably some experimenting.
Free tip - If you are milling your own grain, doing a bit of raw wheat by hand is about as good as a workout at the gym (has been known to stall many drills and to smoke a few motors.
You will also need to take a long hard look at your mill gap, best is to mill the wheat separately, several times starting at just touching the grain, then stepping down until you have a fine kibble with little flour - that will build up your chest arms and probably legs.
When ever I make a Witbier. I use fine grain white / pale bulgur, basically its wheat that has been cracked and then gelatinised, you just throw it into your mash as any malted grain. It will give you the flavour of raw wheat but you do not need to do any extra work. Its cheap, my local Arabic shop sells its for $2.75 a kg.
Years ago ago I was really into Witbier. The recipe I came up with used 45% raw wheat (with 50% pale malted barley and 5% rolled oats). The wheat I sourced was cheap-ass red wheat from the local pet feed supplier, about a dollar a kilo.
My system produces @ 50 litres of finished beer. It's about 82% efficient, so my malt bill generally sits somewhere around the 8-9 kilo mark. Where am I going with this? A ringing endorsement for MHBs comments that milling four plus kilos of raw wheat by hand will give you the upper body strength to take on the Rock! Especially with a hand cranked, screw and plate grain style mill.
I did try boiling the wheat once (the night before brew day) but it set into a brick of unmanageable gloop overnight. Not fun. Research at the time and practical experience tells me you don't need to boil - the cell wall of the wheat becomes porous enough to admit enzymes at around 45 - 50 degrees C (from memory). I used to just do a protein rest at 47 degrees for 45 minutes. It worked fine.
I found the ratios provided above gave sufficient enzymatic horsepower to convert the starches in the unmalted grist. The OG of the beer usually landed close to what it would have if using all malt.
With a style like a Wit, the haze from the residual proteins and so on is a characteristic. They contribute to making it 'white' beer. They also help with forming the white, fluffy head. So for this style I don't use whirl floc/Irish moss - just let all that hazy, crazy wort go straight to the fermenter.
Thumbsuckers approach is one I haven't tried, but looks interesting. I must admit one of the reasons I stopped brewing this was trepidation around getting the grinder out. (I would cheat sometimes by substituting half of the raw wheat bill with malted wheat. Worked okay, but altered the beer profile a bit.)
If you are want my full recipe for Belgian Wit, let me know. It is very, very close to Hoegaarden. You will need some well oxidised hops...
Fwiw, recently reading about someone who did the Weihenstephaner brewery tour and was basically given the wheat beer recipe they've always said the Weihenstephaner was creamier, sweeter and always cloudy so I'm keen to try at least partial unmalted in a standard wheat beer
Personally I would opt for "Raw Wheat" from my local, it’s the same wheat as they use for wheat malt, so it’s selected to be lower in protein and all the other things that make grain malting grade.
Yes its ridiculously expensive for an unmalted product, I suspect that’s just because there is a small demand and it’s a bit of a PITA to bother bagging short runs, so the malting house charges.
White, low protein wheat (not durum) is the best for brewing, strong wheats like durum are very high in glucans and protein which is why they make strong flour, can make for very slow lautering, very cloudy beers and lower yields.
Sure supermarket wheat will work but not as well.