Time-temperature indicator of hydroxyethyl cellulose ink labels for assessing pork freshness

Abstract

Pork is widely consumed worldwide, and many consumers now utilize sensory evaluation techniques to determine the freshness of pork when buying it. A color-changing ink label utilizing bromocresol purple (BCP) and N-hydroxyphthalimide (NHPI) had been created to help consumers better and more rapidly determine the freshness of pork while it is stored. The ink was easy to prepare and could be readily transferred to A4 paper using screen printing technology. This study delved deeper into the impact of hydroxyethyl cellulose (HEC) on the functional properties of inks to enhance printing performance. The experiment demonstrated that a 1 % mass fraction of HEC improved thixotropy and facilitated the even distribution of ink on A4 paper, as confirmed by scanning electron microscopy. Screen-printed labels with varying concentrations displayed distinct color change rates when stored at different temperatures, indicating their capability to assess pork freshness. FT-IR, laboratory, and stability tests verified the ink's exceptional color change capabilities and printing attributes. An analysis using the Arrhenius equation revealed a substantial synergistic effect between BCP and NHPI, resulting in improved sensitivity and accuracy of the ink. This study offers a practical and feasible method to monitor the storage quality of pork effectively.