Immobilization of phospholipase A1 on polyvinyl alcohol microspheres to develop a time-temperature indicator for freshness monitoring of pork

With the goal of improving cold chain logistics and real-time food quality prediction, here a novel time-temperature indicator (TTI) gel based on immobilized phospholipase A1/polyvinyl alcohol microspheres was developed and used to monitor the freshness of cold pork. The morphology, size, and effect of enzyme loading on the PVA microspheres were investigated. Five groups of TTIs were then prepared with the PVA microspheres, and their initial performance was screened in orthogonal experiments. Subsequently, the total volatile basic nitrogen (TVB-N) and 2-thiobarbituric acid (TBA) values from pork, as well as the total color difference of the prepared TTIs, were determined at 4, 15, and 25 C-?, respectively. The activation energies (E-a) were evaluated, and the most similar E-a values were found for TTI, TVB-N, and TBA with 58.15, 59.30, and 57.02 kJ/mol, respectively. In addition, fluctuating temperature tests were designed to verify the performance of the TTI, and the equivalent temperatures of the TTI and pork freshness were determined to be 382.8 and 383.9 K, respectively. The TTI gel developed in this study enables visual monitoring of pork quality and has promising commercialization potential as it overcomes challenges with the cost and morphological stability of other enzyme based TTIs.