You could try rubbing your normal detergent into the stain with a little water leave it 15 minutes then boil wash as normal I have done this lots of times
Use nappy san oxy action plus it removes stains right before you eyes
I think you should try bleaching it, choose higher chemical content bleach so that it could make the stain easy to remove once you wash it again.
Use a cube of ice and let it melt on the stain and rewash the clothing in warm water
Lime juice and salt mixture...put it right on the stain then place clothing in the sun for a few (3-4) hours♥
Depends on what the food was, and what kind of clothes you have. Unfortunately some stains are not much different than the dyes used to color clothes especially after having been set by heat in the drier. One trick I've done for the clothes I couldn't part with was to bleach the heck out of them a few times, then recolor them with dye that you can find in the laundry section of your supermarket. I forget the brand.