Buy some recognized high quality whey made in New Zealand or Ireland or wherever they are sourced from. I've heard of brands like Glanbia and Davisco.
You guys in the US can buy unflavored "raws" from some retailers.
I consider protein powders food. Processed yes, but so are many solid foods too, like cottage cheese, it doesn't come like that out of a cow.
I just bought some expensive Optimum Nutrition powders, supposedly a high quality brand.