UV−Curable antibacterial and pH−sensitive eugenol functionalized chitosan−polyurethane hydrogels for shelf−life extension of chicken

Antibacterial and pH−sensitive eugenol functionalized chitosan−polyurethane hydrogels (UV−EBs) for shelf−life extension of chicken were prepared from thiol−modified chitosan (CS) and UV−curable polyurethanes grafted with eugenol and bromocresol green by UV−curable method. The antibacterial efficiency of UV−EBs is about 55% and 86% respectively after 8 h co−cultured against S. aureus and E. coli . Therefore, a contact−kill mechanism was proposed. Despite the toxicity of UV−EBs against L929 cells increased with the increment of the amount of eugenol groups, the UV−EBs prepared still have potential application in food packing and coatings. Shelf−life extension study for chicken breast demonstrated the UV−EBs can be utilized for packaging materials to extend the shelf−life of high−quality protein food such as chicken breast. The thermal stability of UV−EBs is better than eugenol because the initiate decomposition temperature ( T d5 ) of the former is in the range of 154–175 °C while that of the latter is about 134 °C. Therefore, UV−EBs have potential application in package some food that still has a high residual temperature after being cooked or heated. The UV−EBs demonstrate superior mechanical performance with tensile strength in the range of 0.77–4.90 MPa and the elongation at break in the range of 135–196%, respectively. The UV−EBs also show naked eyes visible color variation from yellow to green and finally to be Prussian blue when the pH values varied from 2 to 14. This work supplied a feasible method to develop antibacterial hydrogels for packaging materials to extend the shelf−life of high−quality protein food.