I read an article a few years back, about some expose' some media agent did on "food glamour", which was food advertising.
To make things like turkeys and steaks look all cooked to perfection, they would coat them with motor oil.
To make veggies look "hot", "buttery", or "glossy", they would put in some kind of liquid silicone product.
Cakes would be frosted with plaster in order for the "frosting" to not melt under the hot lights.
Pies would be glazed with shellac or varnish to keep the crust or the top of the pie from drying out under the lights, and keep it looking moist.
They had an estimated total of food wasted in making advertising for said food products, I dont remember the exact amount at that time, but it was into the millions per year.
SO much food is wasted in advertising. So much food, that it could feed the homeless and needy in one country for years.