Containers come in a wide variety ranging from very porous to so-called barrier bags which are made of films that completely eliminate gas flow. Large companies like Fresh Express make use of that technology, Mount said. But you have to produce a lot of a product to make it cost effective to stock a bag for a particular item. That's why his work in classification will help, especially smaller companies, to use the same package for more than one thing. The most basic approach, Mount said, is to allow the produce to generate its own atmosphere within the bag.
Produce respires-that is, it uses oxygen and gives off carbon dioxide.
A bag containing mostly carbon dioxide will keep the vegetable fresh longer. But too much can be worse than too little, he said. So an ideal package would allow a little oxygen to pass through, but not much. Just how much is the question, Mount said, and that varies from vegetable to vegetable. Part of his work is to classify vegetables and packaging into categories that manufacturers can use to determine which bag or box works best for which fruit or vegetable.