Time Temperature Indicator Label using Black Corn Extract and Chitosan Matrix

Time-temperature indicator (TTI) labels have been widely researched and some have been used commercially due to their ability to provide food product quality information through changes in label color when exposed to temperature over a specified period of time. The TTI label consists of functional dyes and matrices. The purpose of this study was to develop a TTI label that uses natural dyes derived from black corn extract and chitosan as the matrix. Labels were prepared using a simultaneous method then casted on top of PET substrate. Absorption properties of the black corn extract was investigated by using UV-Vis Spectrophotometer. The label colors were characterized using digital photography and analyzed with CIELab color code. The color of the labels were observed over time at temperature conditions of 10, 25 and 40 °C. The extract solution is red at pH 2-3, then pink at pH 4-5, purple at pH 6-7, violet at pH 8, and turned to yellow at pH 9-13 which indicates that the extract contains anthocyanin. Due to time period, the label changes color from purple to blue to yellow, with the fastest color changes occurred at higher temperature of 40 °C and slowest at lower temperature of 10 °C. The shelf life test on different RH conditions shows that the label stored at RH 33% is more stable than at higher RH of 76%. The labels show irreversible properties which is one of the requirements as a time temperature indicator label. These results indicate that the label of black corn extract with chitosan has the potential to be applied on smart packaging.