Effects of Ultrasonication in Water and Isopropyl Alcohol on High-Crystalline Cellulose: A Fourier Transform Infrared Spectrometry and X-ray Diffraction Investigation

Structure of Cellulose Isolated from Rapeseed Stalks

Solid state Cross-Polarization/Magic-Angle-Spinning 13C CP/MAS Nuclear Magnetic Resonance (NMR) spectra were obtained for cellulose and α-cellulose isolated from rapeseed stalks. This study provides the first characterization of the rapeseed stalk cellulose, revealing that native cellulose occurs as cellulose I allomorph, while α-cellulose exhibits distinct crystalline structures similar to those found in cellulose II. Additionally, Fourier Transform Infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM), and Energy-Dispersive X-ray Microanalysis (EDX) were employed to further investigate and unveil the structural properties of cellulose extracted from rapeseed stalks. These complementary techniques offered a more comprehensive understanding of the cellulose morphology, crystallinity, and chemical composition, providing valuable insights into the potential utilization of rapeseed stalks as a renewable biomass resource for various industrial applications.

The mechanisms of inactivation of polyphenol oxidase in fresh-cut Agaricus bisporus by dual-frequency ultrasound combined with electrolytic water

Fresh-cut mushrooms are gaining popularity worldwide. However, their shelf life is limited because of enzymatic browning catalyzed by polyphenol oxidase (PPO), which leads to quality loss. The effects of different treatments (dual-frequency ultrasound (DFU), electrolytic water (EW), dual-frequency ultrasound combined with electrolytic water (DFU-EW)) on the molecular structure (Fourier infrared spectroscopy, X-ray diffraction, fluorescence spectroscopy, surface hydrophobicity, etc.), thermal properties, gene expression of PPO, and storage characteristics of mushrooms were investigated. The results showed that the DFU-EW decreased the relative contents of α-helix by 6.3 % and β-turns by 11.2 %, while increasing the contents of random coil and β-sheet by13.3 % and 4.7 %, respectively, compared to the control. The XRD analysis showed that the crystallinity of PPO was 7% higher than the control, while the fluorescence spectroscopy and surface hydrophobicity of PPO decreased from 921.7 (a.u) and 1154.5 to 393.5 (a.u) and 506.5, respectively. The DFU-EW treatment changed both the secondary and tertiary structures of PPO. The TGA analysis indicated that the thermal decomposition temperature decreased from the control 351.4 ℃ to 336.9 ℃. The gene expression level of AbPPO3 and AbPPO4 lowered. A 7-day storage period showed that DFU-EW inhibited the degree of browning, maintained the firmness of mushrooms, and stabilized the relative activity of PPO at 60% on average. Taken together, the DFU-EW treatment can effectively inactivate the PPO activity in fresh-cut mushrooms, thereby extending their shelf life, and this method provides a new insight to improve the quality of fresh-cut products.