The TimeeTemperature Indicator colour parameters were
determined in a MiniScan EZ Hunterlab spectrophotometer. The
values of L* (lightness), a* (red e green) and b* (yellow e blue)
parameterswere recorded to evaluate colour changes due to the TTI
contacting solutions in different pH ranges (1.0e12.0). Tests were
performed in triplicate and the total colour differencewas obtained
according to the Equation