A method and apparatus is provided for formulating meat blends to a desired fat percentage by continuously measuring in a non-destructive manner the percentage of fat in meat streams while they are flowing, and thereafter blending the streams into the desired formulation. Although the meat streams are of non-uniform consistency and density, accurate blending is accomplished by including a sensor that automatically and continuously monitors the meat streams to enable corrections for such non-uniformity. Percentage fat measurements are made by passing a beam of polychromatic X-rays through the streams and measuring both the incident and attenuated beams.