Actually. It depends whether the produce is meat or veg and it depends how the foods will be used.
I was pretty annoyed to say the least when I received premium organic turkey fillets (with every scrap of white stringy bit chopped carefully out) instead of the cheap stuff which is cheap purely because it has more stringy bits in it and looks less attractive. The cost was a difference of £5 per pack and I needed 3 packs, these things happen when people go on holidays etc unfortunately.
This turkey breast was going to go through a meat grinder to be used in a premixed food for Haitian Galliwasps, I'd much rather save £15 and work harder getting it through the grinder.
Pears for instance are a fairly expensive fruit, we buy bruised or overripe pears for some animals which cuts the cost by some 50%. In Herps we use pears sparingly, for things like asian turtle greens or pyxis greens, both of these groups would typically encounter fallen, bruised, overripe fruits in the wild, this is what they prefer.
The wastefulness of humans is disgusting, food that is rejected because it's odd shaped, got soil on it or is two days past it's "display by" date could hardly be used more appropriately than to contribute to zoo animals diets at a lower cost. Saving money and reducing wastage!
I shop from the reduced sections myself and I certainly don't buy anything "grade A", it's just ridiculous, you're talking about food that has left a trail of waste or reduced worth along the way as the majority of produce doesn't make the grade.
I don't think our animals care about whether someone delicately brushed all of the dirt off their green beans, ensured that the carrots grated for them were of a standard shape to start with, checked that every food item they get was comfortably in date or else it's poison.
You may be interested to know though, we've run our own organic farm for a number of years already to provide the majority of our needs and produce species specific food items that cannot be purchased.
The priority for captive animals is to be provided with a nutritionally suitable and varied diet which is presented in an appropriate fashion for their needs.