Procedural meat texture (the .blend contains the node tree). Very much played by eye rather than science; though I did try to discover a suitable IoR, and the easiest to find was in Wikipedia's List of Refractive Indices which gave me that of, er, the human liver. Fava beans and chianti not included.
I gave up on adding SSS to the Sketchfab material; it just made the appearance blurrier. Here's the Eevee output for comparison:
![Eevee rendering](http://rfjseddon.net/ext/meat.png)