Study on film forming characteristic of e-polylysine grafted chitosan through TEMPO oxidation system and its preservation effects for pork fillet

The present study synthesized a new type of e-polylysine (PL) modified chitosan film (TO-CH-PL) through TEMPO (2,2,6,6-Tetramethylpiperidine) oxidation system. Firstly, the physicochemical properties of the TO-CHPL were characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, and energy dispersive spectrometer analysis. Results proved that PL was successfully grafted onto chitosan molecules. Based on the water vapor, oxygen permeability, and mechanical analysis, the TO-CH-PL film demonstrated higher physical properties than chitosan and PE films. Secondly, the TO-CH-PL film's preservation effect on pork fillets was evaluated. Due to the significant retardation of growth of the aerobic plate count (APC), total volatile basic nitrogen (TVBN), and thiobarbituric acid reactive substances (TBARS), as well as the changes of pH and color in packaged pork, TO-CH-PL film exhibited better preservation effects for the pork samples. According to the criteria of TVBN values (<15 mg/100 g), compared with CH and PE films, TO-CH-PL film can prolong the shelf life of pork for 2 to 3 days. Therefore, PL-modified chitosan films could be introduced as an alternative method to maintain the quality indices and extend the shelf life of pork during refrigerated storage.

Automated summary

The present study synthesized a new type of e-polylysine (PL) modified chitosan film (TO-CH-PL) through TEMPO oxidation system. The physicochemical properties of the TO-CH-PL film were characterized and proven to be superior to chitosan and PE films in terms of water vapor, oxygen permeability, and mechanical analysis. The TO-CH-PL film showed better preservation effects for pork fillets, as it significantly retarded the growth of bacteria, reduced the levels of volatile basic nitrogen and thiobarbituric acid reactive substances, and maintained the pH and color of packaged pork.