Abstract: Modified guar gum and whey protein were used as raw materials for the preparation of a composite film. It was found that when the mass ratio of modified guar gum and whey protein was 1:0.6, the best mechanical properties, barrier properties, and thermal stability of the composite film were obtained; the tensile strength (TS) of the film was 39.92 MPa, the elongation at break was 31.13%, and the thermal decomposition temperature was 147.85 ℃. The composite film could effectively remedy the defects of the single-component films. In addition, the results of scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) indicated that the film was smooth and transparent, and the compatibility between modified guar gum and whey protein was good. A modified guar gum/whey protein/rutin composite film (G’/W-R) was prepared by adding rutin to the film. Addition of rutin was found to impart good antioxidant activity to the film. Meanwhile, when applying the composite film to Agaricus bisporus preservation, it was found that G’/W-R could effectively delay the browning of mushroom, maintain high hardness, and inhibit the respiratory rate; the peak respiratory rate was only 2.8 × 103 mL/(kg·h), and the overall mass loss rate was only 25% of the control group. Moreover, this treatment effectively suppressed the levels of hydrogen peroxide (H2O2), superoxide anion radical and malondialdehyde (MDA), which was conducive to maintaining the integrity and stability of the cell membrane. Also, it terminated the free radical chain reaction, maintained the activities of peroxidase (POD), superoxide dismutase (SOD) and catalase (CAT), removed the excess reactive oxygen species (ROS) in mushroom tissues, and consequently the shelf life of mushroom.

Key words: guar gum; whey protein; rutin; Agaricus bisporus; preservation