Antibacterial smart absorbent pad with Janus structure for meat preservation

In this work, an antibacterial smart absorbent pad with Janus structure was prepared to preserve and indicate the quality of meat. The pad had two layers, polyurethane (PU) nanofibers as the top hydrophobic layer and polyvinyl alcohol (PVA) nanofibers as the bottom absorbent layer. Polyhexamethylenebiguanide hydrochloride (PHMB) was added to the top layer as cationic antimicrobial agent because guanidine group could maintain its strong positive charge in alkaline environment, which keeps the antibacterial ability during meat spoilage that is a process of pH increasing. Besides, the juice of the meat can be absorbed to the bottom layer while the hydrophobic top layer in contact with meat remains dry, which can reduce the multiplication of bacteria. Furthermore, anthocyanin was added to the bottom layer as an indicator to detect spoilage of meat. The experiments show the new antibacterial indicator absorbent pad can effectively inhibit bacterial growth (less than 5 lg CFU/g after 8 days), prolong the shelf life of fresh meat (total volatile base nitrogen less than 20 mg/100 g) to 7 days when stored at 4 °C and indicate the deterioration of meat.