Gamma Induced Synthesis of pH Responsive Chitosan-Based hydrogel for Real-Time Ammonia Detection in Environmental Monitoring and Food Preservation Application

A green pH responsive chitosan-based hydrogel was prepared and applied for real-time ammonia detection and monitoring. The hydrogel was prepared by gamma induced crosslinking process between chitosan, starch and acrylic acid. The synthesized hydrogel was coded as CS/ST/PAAc. The optimized irradiation dose was determined through a gel percentage study and verified using AFM analysis. The synthesized hydrogel was characterized via different analytical tools such as IR, XRD, SEM and AFM. Then, the optimized CS/ST/PAAc was loaded with methyl red dye for investigating the pH responsive behavior. The effect of pH on swelling and dye loading capacity of the hydrogel was also studied. Comprehensive colorimetric and optical studies for the pH stimulation as a function of time and ammonia concentration were performed. Practical applications of the versatile gel sensor were tested in solution and in the gaseous phase. Then, the workability of the sensor was tested for monitoring the spoilage of chicken and fresh meat samples through real-time ammonia detection. The data revealed that the prepared hydrogel was very promising material for detecting and following-up ammonia gas. This feature makes the synthesized hydrogel an excellent candidate for smart food packaging, particularly for packaging meat and marine food products, as well as for monitoring industrial by-product ammonia.