Let me offer up my 2 cents
We do not have the 50mm 1.8 or the 50mm macro, but We do own the 50mm 1.4 and the 100mm macro. From what I have seen and read, the picture qualities and color rendition are a little better on the 1.4 than the 1.8. The 1.4 is also sharper at F1.8 when compared the 1.8 at F1.8. In most circumstances for food photography, you will not likely be shooting wide open, except in the case of dark restaurant where the 1.4 will be better. For the price I would go for the 50mm F1.8.
But looking through your site, most of your shots are close up of the finish product or ingredients. Then I would suggest you save your money and get the 100mm Macro. As the 1×1 can really capture the details where as the 50mm F1.8 cannot, due to the minimal focusing distance. This is one of the sharpest lens we own even when comparing with our other L lenses. With the introduction of the new 100mm Macro F2.8L IS series, you will probably see more of the older version on the used market. Check with your local Craigslist to see if there any available. Used can be bought for around $400. The only downside to this lens is taking overhead shots of your setup as you might need a ladder and extended tripod to get everything into frame. Definitely don’t think you will regret buying this lens in the long term.
If you want to see some samples, feel free to browse our site. Most of the photos are taken with the 100mm macro, the wider shots are taken with the 50mm 1.4 or the 24mm 1.4.
Hope this helps