No, raw is absolutely not a file format. It merely describes the file format, which is simply the common word describing the unchanged state of the file or capture, or yes, even uncooked meat in your example. CR2 or NEF (Canon and Nikon, respectively), for example, are the file formats for the raw capture, which are acronyms. Even if raw was a file format, and because it is not an acronym, it would have to be spelled, "Raw." So, ultimately, is undeniably incorrect to capitalize all letters.