TABLE OF CONTENTS Red wines and some aged cheeses are just about the only packaged foods that get better as they get older. Beyond this well known fact, virtually all food products deteriorate over time. As a result, packaging researchers are developing technology to slow that deterioration and, in some cases, to use the package in actively improving food quality. Semi-rigid plastic and flexible packages are taking over an increasing share of the packaging market from glass, jars and metal cans; demand for glass, cans, and paper-board is stalled, while plastic and flexible package use is growing. This trend is driven both by cost and functionality. Using ketchup, as an example: it is very oxygen-sensitive, and therefore it must have a very high oxygen barrier material in order for it not to darken and solidify. Unfortunately although glass fits the bill , for oxygen permeability, people like ketchup in a squeezable bottle, a function which cannot be obtained with glass. Oxygen permeability is an issue with plastic bottles, too. Oxygen gets in and makes the product go bad with common plastics, whereas this does not happen with glass. On the other hand, plastic takes up less room, weighs less, and does not break, this quality being particularly attractive for beer sales at sporting events and concerts, where plastic bottles are often thrown away. The can also suffers from consumers impressions about canned food, including that the interior coating does not look good, and also...
