I don't make it often (not a fan), but my recipe doesn't include........
(HYDROGENATED LARD, BHT AND CITRIC ACID PRESERVATIVES), CONTAINS LESS THAN 2% OF: , TRICALCIUM PHOSPHATE, SODIUM ACID PYROPHOSPHATE, MONOCALCIUM PHOSPHATE, NIACIN, REDUCED IRON, THIAMINE MONONITRATE, RIBOFLAVIN, FOLIC ACID, WHEAT STARCH
FWIW.... If I seem to have be anal about additives, I am. It's can be annoying. Sorry.
As I've never tried Jiffy, so I can't comment on taste or texture. I always thought of cornbread as something made up with pantry staples.
I just use a recipe like this. (with less sugar)
1 cup all-purpose flour 1 cup yellow cornmeal 2/3 cup granulated sugar 1 teaspoon salt 3 1/2 teaspoons baking powder 1/3 cup neutral oil or melted butter 1 large egg 1 cup milk