Lifelines' Freshness Monitor and Fresh-CheckTM indicators rely on a solid state polymerization reaction to give color changes. The indicator consists of a small circle of a polymer surrounded by a printed reference ring. The inside polymer circle dark- ens if the package has experienced unfavorable temperature exposures(Summen, 1992b), and the intensity of color is measured and compared to the reference col scale on the lab(de Kruijf et al., 2002). The faster the temperature increases, the faster the color changes occur in the polymer Consumers are advised not to consume purchase the product, regardless of the use by date. These indicators have been used on fruit cake, lettuce, mil chilled fresh produce, and orange juice