Structural characterization of a nano-TiO2/SiO2 composite film and its preservative effect on Agaricus bisporus

In this study, carrageenan/konjac glucomannan films were modified by addition of nano TiO2 / SiO2 and ultrasonic dispersion. These films were characterized by Fourier transform infrared (FT-IR) spectroscopic analysis and scanning electron microscopy (SEM).Effects of the modified nano-composite film on postharvest physiology and quality of Agaricus bisporus during storage at 2 were studied. The results showed that nanoparticles in the carrageenan/konjac glucomannan/nano-TiO2 composite film, subjected to ultrasonic treatment were highly dispersed. There were a great number of hydrogen bonds between nano-sized SiO2 particles and hydroxyl groups on the surface ofcarrageenan/konjac glucomannan. After 12 d of storage, the values of whiteness, firmness of flesh, and soluble solid content (SSC) of Agaricus bisporus treated with the modified composite films were 87.75 (flesh) and 82.48 (skin),9.0×105 Pa and 6.9%, respectively, which were significantly higher than those of the control group (84.22 (flesh) and 78.48 (skin), 7.6×105 Pa, and 5.3%). In addition, the modified carrageenan / konjac glucomannan /nano-SiO2 composite films delayed the increase in relative conductivity as well as weight lossin Agaricus bisporus, significantly inhibited the activity of peroxidase (POD) and delayed the peak of polyphenoloxidase (PPO) activity, thus remarkably improving the preservation of Agaricus bisporus.