Pathogens can contaminate produce through wounds. Give the produce a smooth ride, not bumpy. Optimum temperature is the most important factor to maintain quality. A continuously flowing cold water bath conducts heat away. Do not hydro-cool eggplant, garlic, or onion.
Amount varies with crop.
No rough surfaces, sharp edges, or nails which could puncture or wound. Prevent water loss by covering stacks of produce with tarps, or packing it into bags of either paper or plastic. Microperforated plastics have tiny pores to let condensation out. Don't underfill boxes and don't overfill, but hold items tight within the box. Pack to immobilize, cushion, and avoid impacts.