Usually you can try to heat the water to increase the dissolved substance. Also the quantity you want to dissolve plays a role. Maltodextrin might be then form a viscous and turbid fluid as it's an oligosaccharide, perhaps this might be the observed precipitate?
I'm not sure how good maltodextrin is defined so solubility surely depends on the composition of the actual chemical you have: the more short chains you have the easier and the more will be dissolved. If you have mostly long chains it will become much more difficult (the chains vary from 2 to 20 sugar units), as it's more like starch then.
And why do you compare with lactic acid? This is a quite different molecule with different properties and size.