Problem definition and objectives: This study aims to investigate the antibacterial properties of papers treated with plant extracts derived from the leaves, bark, and wood of oak and eucalyptus trees. Given the growing bacterial resistance to antibiotics and the increasing demand for hygienic packaging, utilizing natural antibacterial compounds from plant sources can provide an effective solution for the food and healthcare industries. Plant extracts contain active compounds such as flavonoids and tannins, which can disrupt bacterial cell structures and inhibit their growth. In this research, ultrasonic extraction was employed to maximize the efficiency of extracting bioactive compounds. Handcrafted paper with a grammage of 120 g/m² was produced, and then the extracted solutions were sprayed onto the paper surface, followed by assessment of antibacterial and mechanical properties.
Methodology: The methodology involved preparing kraft pulp from long-fiber wood, extracting plant compounds, and producing paper. Plant extraction was conducted using ultrasound in acetone as a solvent to ensure high-yield extraction in a shorter time. The extracts were treated at two different ultrasound amplitude levels, and the prepared paper samples were treated with the extracts and air-dried before undergoing various tests, including antibacterial and mechanical evaluations. The antibacterial properties were assessed by measuring the inhibition zones against gram-positive Staphylococcus aureus a, Escherichia coli b.
Results: The results showed that leaf and bark extracts of oak and eucalyptus exhibited stronger antibacterial activity compared to wood extracts. Staphylococcus aureus was particularly sensitive, forming inhibition zones of varying diameters. Among the extracts, oak leaf and bark were most effective against Escherichia coli, with inhibition zones of 13 and 18 mm, respectively, while wood extracts showed lower activity. This difference was attributed to active compounds such as flavonoids and tannins in the leaves and bark, which can more effectively penetrate bacterial cell walls. Mechanical tests revealed that adding the extracts led to a noticeable decrease in the mechanical strength of treated paper compared to the control. This reduction was mainly due to the weakening of hydrogen bonds between cellulose fibers and the presence of hydrophilic compounds in the extracts.
Conclusion: In conclusion, this research demonstrates that plant extracts from the leaves and bark of oak and eucalyptus trees can serve as potent natural sources for producing antibacterial papers. However, due to the adverse effects on paper’s mechanical properties, incorporating reinforcing additives alongside these extracts is recommended. This approach can foster the development of antibacterial paper products suitable for hygienic and food packaging applications, offering a sustainable and safe solution for maintaining public health and hygiene.