Evaluation of time-temperature integrators for tracking poultry product quality throughout the chill chain

The goal of this study was to evaluate the application of one type of time-temperature integrator (TTI) to monitor the microbiological quality of ice-packed raw chicken drumsticks as a function of temperature exposure. A kinetics-based model was used to correlate the TTI chroma response to the number of bacteria on the drumstick surface under constant- and variable-temperature conditions. Two constant-temperature studies (4 and 15 degrees C) and one variable-temperature study (4 degrees C for 24 h, 15 degrees C for 24 h, 4 degrees C constant) were conducted to evaluate the applicability of the TTI under ideal and worst-case situations. During the constant-temperature studies, quality predictions made at the midpoint of the product shelf life were accurate within 15% for the observed bacterial populations. The accuracy of the TTI was marginal in the initial and final stages of the response period. During the variable-temperature study, the TTI response demonstrated positive history effects, whereby the observed rate constant is affected by previous temperature exposure. After the TTIs had been held at 15 degrees C for 24 h, the TTI response rate constant observed during subsequent storage at 4 degrees C was higher than what would be predicted for 4 degrees C. Further work will be needed to develop a continuous TTI-based quality monitoring system. However, because the microbiological quality of fresh poultry could be reliably predicted with kinetic models, fresh poultry products would be excellent candidates for a TTI-based quality monitoring system.