OnVu time-temperature indicator (TTI) system

OnVu is a time-temperature indicator (TTI) system that monitors the freshness of perishable goods. OnVu TTIs are supplied as either printing inks or labels and can, in principle, be used for any product that is sensitive to temperature. Once activated by a suitable light source, the TTI first becomes dark and then grows progressively lighter as time passes, and if and when the ambient temperature rises. Exposure to higher temperatures than those prescribed accelerates the lightening process of the color. When the activated color attains the same shade as the reference, the product has reached the end of its shelf life. The indicators give a visual summary of a product’s accumulated chill-chain history, recording the effects of both time and temperature. Every indicator is tailored to the shelf life and optimum storage conditions of the product it is designed to monitor. While these TTIs are designed for meat, fish, dairy products and convenience foods with a shelf life of 5–6 days at 5°C, under development are TTIs for products with a shelf life of one week and more.