Valorization of Larix decidua Mill. bark by functionalizing bioextract onto chitosan films for sustainable active food packaging.

The present study explored the use of chitosan films functionalized with antioxidants extracted from Larix decidua Mill. bark for active packaging. The pristine chitosan and extract-incorporated chitosan films were evaluated for their structural, physico-mechanical, thermal, viscoelastic and antioxidant properties using advanced characterization techniques. The infrared spectroscopy revealed hydrogen bonding between the extract polyphenolic antioxidants and chitosan, whereas the surface microscopy studies indicated good compatibility between them. The addition of bark extract caused a significant increase in color parameters and solubility with reduction in swelling and elongation at break of the films. The thermal analysis indicated a drop in thermal stability of chitosan films modified with the extract. The dynamic mechanical analysis confirmed the extract-polymer interactions and the viscoelastic nature of the films. The incorporation of bark extract caused remarkable enhancement in the antioxidant activity of chitosan films. Overall, larch bark extract-functionalized chitosan films demonstrated promising potential for food packaging.

Assessment of the papermaking potential of processed Miscanthus × giganteus stalks using alkaline pre-treatment and hydrodynamic cavitation for delignification.

One way of satisfying increased market demand and simultaneously achieving a reduced environmental load in the industrial paper production is the use of fibrous agricultural residues. The aims of this study were i) to investigate the effect of alkaline - hydrodynamic cavitation (HC) pre-treatments on the delignification of Miscanthus × giganteus stalks (MGS) and ii) establishing the suitability of MGS as feedstock and their exploitation in pulp and paper manufacturing. It was demonstrated that the proposed treatment is an efficient delignification method for the non-wood fiber sources, such as miscanthus. A significant outcome of this work was the observation that HC treatment preserved the fibres lengths and surface quality of raw MGS, but at the same time increased the amount of kinked and curled fibers present in cavitated miscanthus fibers. The average miscanthus fiber length was found to be relatively short at 0.45 (±0.28) mm, while the slenderness ratio, the flexibility coefficient and Runkel ratio values were calculated to be 28.13, 38.16 and 1.62, respectively. The estimated physical properties of MGS pulp hand-sheets were 24.88 (±3.09) N m g-1 as the tensile index, 0.92 (±0.06) kPa m2 g-1 as the burst index and 4.0 (±0.37) mN m2 g-1 as the tear index. Overall the current work demonstrated effective use of hydrodynamic cavitation for improving the processing in pulp and paper manufacturing.

Formaldehyde Adsorption-Desorption of Poplar Bark.

This study investigated how the Populus × euramericana cv. Pannónia bark behaves in an environment containing formaldehyde. Prism shaped samples were formed from the bark and the prisms were kept in formaldehyde contaminated atmosphere for 1, 2, 5, 10, 18 and 36 days. After the contamination, the amount of the formaldehyde adsorbed and later the desorbed was measured. The formaldehyde content of the uncontaminated poplar bark was 0.0036 mg/g. The amount of bound formaldehyde showed a saturation curve as a function of time. The formaldehyde adsorption reached an equilibrium value of 0.9 mg HCHO/g bark. The emission of formaldehyde from contaminated bark samples showed an exponential curve as a function of time and some residual formaldehyde content was detected after the formaldehyde was released.