[musseldoc]

If I add pumpkin (canned) near the end of the boil, then will I have a starch haze in my beer.  Or will the boiling break down the large starch chains?

[a10t2]

Pyrolysis of starches isn't going to happen in the boil; it isn't nearly hot enough. You will probably have some haze. You might be able to remove it with filtration or finings, or even just enough time.

[kramerog]

You will likely get a pectin haze.  The haze may fall out.  You could add a pectinase to the fermenter to break down the pectin.  Generally, pectinases work better at the start of fermentation.  Pectinase is readily available at winemaking supply places.

[HoosierBrew]

You will likely get a pectin haze.  The haze may fall out.  You could add a pectinase to the fermenter to break down the pectin.  Generally, pectinases work better at the start of fermentation.  Pectinase is readily available at winemaking supply places.

+1.  Sometimes labeled as 'pectic enzyme' at LHBS that sell winemaking supplies as well.

[duncan]

From my recent experience, I'd expect a little haze but nothing off putting. In my last brew I used pumpkin in the mash and mid-boil, used SuperMoss in the boil, only did a primary, and cold crashed for a few days before kegging. The first few pints from the keg were foggy, as you'd expect, but now it is nearly crystal clear with the slightest haze. I was pleasantly surprised considering the minimal effort I put into ensuring clarity.

I'd say use some form of Irish Moss, consider a secondary and cold crash and you'll likely end up with something that isn't super foggy.

$0.02