6 July 2006 -An Agricultural Research Service (ARS) scientist has identified specific packaging wraps, called films, which provide several fruit and vegetable varieties with a long shelf life. Food technologist Yaguang Luo, with the ARS Produce Quality and Safety Laboratory (PQSL), Beltsville, Md., led the project. The technology she used is known as "modified atmosphere packaging," or MAP.
Fresh-cut fruit and vegetable varieties are still alive, and each respires at its own unique rate. Therefore, a film's permeability and the amount of oxygen initially infused into a package are key.
Manufacturers have produced hundreds of different types of films, and each type has its own oxygen transmission rate, which allows sliced produce to continue breathing throughout storage and distribution. If a film's oxygen transmission rate is too high for the variety it's wrapping, the product inside will brown; if it's too low, the product will prematurely decay.
Luo's research findings led to developing a balance of oxygen and carbon dioxide inside select packages that permits a particular fresh-cut produce variety to respire slowly and stay fresh for the longest possible time.
For example, fresh-cut cilantro--a leafy culinary herb that's a popular flavor component of tomato salsa--has a high respiration rate that makes storage a challenge. Leaf yellowing, dehydration and loss of aroma can set in quickly after cutting. The packaging film Luo has identified for wrapping cilantro provides a 14-day shelf life. So the cilantro has plenty of time to be plucked from the grocery shelf and chopped to enliven a fresh batch of salsa.
Using similar advanced packaging technologies, Luo has been able to prolong the shelf life of romaine lettuce, iceberg lettuce, carrots and salad savoy, a nutritious new vegetable crop that is a close relative to kale and cabbage.