Temperature‐ and pH ‐Responsive Chitosan‐Based Aerogel for Tomato Preservation

ABSTRACT

To address the limitations of food packaging in terms of active preservation and freshness indication, chitosan (CS) and polyvinyl alcohol (PVA) were used as the main matrix materials, while the thermoresponsive component poly(N‐vinylcaprolactam‐co‐acrylamide) [P(NVCL‐co‐AM)], the pH‐responsive indicator alizarin (AL), and in situ‐generated TiO ₂ nanoparticles were incorporated. The resulting composite aerogel, denoted as PCN@Ti/AL, was then prepared through freeze–thaw cycling and freeze‐drying. X‐ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analyses showed that the TiO ₂ was successfully incorporated into the system, and CS, PVA, P(NVCL‐co‐AM), and AL were mainly associated through hydrogen‐bonding interactions. The pH‐responsive experiments demonstrated that PCN@Ti/AL exhibited color changes over the pH range of 1–13. In addition, its color gradually changed from orange‐red to yellow as the pH of cherry tomato juice decreased at different storage stages. Differential scanning calorimetry (DSC) results showed that the aerogel exhibited a thermoresponsive thermal transition at approximately 25.9°C. Antibacterial tests indicated that PCN@Ti/AL achieved an antibacterial rate of up to 99%. During the 18‐day storage experiment, PCN@Ti/AL‐4 effectively delayed moisture loss and the deterioration of the appearance quality of tomatoes, demonstrating excellent preservation performance. These results demonstrate that PCN@Ti/AL has potential for application in multifunctional fruit preservation and freshness‐indicating packaging.