The properties of chitosan/zein blend film and effect of film on quality of mushroom (Agaricus bisporus)

A series of chitosan/zein blend films in different proportions were prepared. Firstly, the chitosan and zein solutions were blended in different volume ratios:1:0 (C/Z-0), 1:1 (C/Z-1), 3:1 (C/Z-3) and 5:1 (C/Z-5). The zeta potential was measured to investigate the stability of film-forming solutions. The mean values of zeta potential ranged from + 30.37 to + 44.27 mV, which indicated the excellent stability of all film-forming solutions. The physico-chemical and thermo-mechanical properties of films were evaluated by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The results indicated that the parameters such as water vapors, oxygen and carbon dioxide barrier in the blend films were improved compared with pure chitosan film. FTIR analysis showed that hydrogen bond interactions existed between zein and chitosan molecules. SEM and XRD results confirmed that chitosan and zein had good binding compatibility. TGA demonstrated that the addition of zein improved the thermal stability of films. In addition, the effects of films packaging on the physicochemical properties of mushroom during storage at 4 °C for 12 d were studied. Among all the treatment groups, mushroom packaged with the blend film with a mixing ratio of zein: chitosan (1:1) exhibited the lowest weight loss rate, respiration rate, relative leakage rate, PPO and POD activity, however, the highest whiteness index.