Agree with Octarine. Lighting and composition are the two most important things in food photography (or any photography in general). That being said, if you do wanna pick a lens with good bokeh, I'd vouch for the Olympus 25mm f1.8. Personally I don't shoot on m4/3, but from my friends that do, they do love the focal length and the bokeh on the lens alot. Wide enough to give some context in the background, yet have enough background blur to bring focus to the subject (pun unintended).