When contemplating using corn or rice to make CAP's, there is no better expert thna Jeff Renner and there was a huge amount of stuff on the Home Brew Diest (HBD) well over 10 years ago.
The first mistake is to confuse 'cornie' flavour of European or Asian made beers with those using corn. This relates to a DMS profile, not corn, and is not acheivable with the JW Export Pils or Barretts varieties availible in Australia. That being said, I have no doubt malt is produced from these manufacturers with the DMS precursor, but it is not sold and not acheivable, no matter what the ney-sayers say...
Flaked corn is heated via steam and rolled, hence gelatinising the product, fit for chucking straight in. Polenta I have alwasy 'cereal cooked' via boiling, like rice, to gelatinise. I have just stumbled on a powdered maize from an Asian store in Randwick which I am about to play with. It is amazing that at the turn of the 18th century Centuries needed to be posted at wheat and corn feilds to save the crop from brewers wanting to pinch the products for use in brewing, but now finding locally produced flaked maize is now near imposible, save for the UK stuff.
THe maize/polenta will give a stiff white head and a smoothness to the beer. Also helps to lighten the profile, but I suspect from the proteins added does not give the dry finish as you get when using amalayse in a low carb beer.
Research the info from Jeff Renner and that will set you on the correct path of enlightenment. From my own experience, for a CAP 10-20% maize/rice with halletau and a damm good lager yeast and 10C ferment is a match made in heaven.
scotty
ps. Skinny Blonde from Brothers Inc uses flaked rice in thier low carb beer, probably the tastiest low carb beer on the market and the only one I would buy ... but I have a vested interest as one of the contract producers ....