How does a TTI differ from a chemical indicator in process validation?

• A. A TTI confirms exposure timing and temperature, while a chemical indicator confirms exposure based on a chemical change
• B. They are the same
• C. A chemical indicator confirms exposure timing and temperature; a TTI confirms chemical change
• D. A TTI measures pH; a chemical indicator measures color

Answer: (A)

Time-temperature indicators (TTIs) are designed to capture the product’s actual thermal history, showing how long and how hot the product has been exposed. This lets you confirm that the required time at the target temperature was achieved. Chemical indicators, on the other hand, respond to a chemical change that occurs under the exposure conditions, typically changing color to signal that a threshold condition was met, but they don’t provide a time-temperature history. So TTIs verify exposure timing and temperature, while chemical indicators verify exposure through a chemical change.