Maltodextrine is mostly non fermentable, it is good for adding mouth feel, body and head retention to brews without affecting flavor.

Adding Maltodextrin to your extract brew will help you fine-tune the body and mouthfeel without affecting the flavor. The Maltodextrin molecule is a chain of sugars between 4 and 20 dextrose units in length. That means it is only 3% fermentable by brewer's yeast, and so will contribute body to the finished beer. It is naturally present in all finished beers, up to 6% by weight, but the grains that yield it in All Grain brews don’t respond well to steeping in extract batches.