Is there a way to force ASP.NET Web API to return plain text?

I need to get a response back in plain text from a ASP.NET Web API controller.

I have tried do a request with Accept: text/plain but it doesn't seem to do the trick. Besides, the request is external and out of my control. What I would accomplish is to mimic the old ASP.NET way:

context.Response.ContentType = "text/plain";
context.Response.Write("some text);

Any ideas?

EDIT, solution: Based on Aliostad's answer, I added the WebAPIContrib text formatter, initialized it in the Application_Start:

  config.Formatters.Add(new PlainTextFormatter());

and my controller ended up something like:

[HttpGet, HttpPost]
public HttpResponseMessage GetPlainText()
{
  return ControllerContext.Request.CreateResponse(HttpStatusCode.OK, "Test data", "text/plain");
}