The use of Thyme extract (Zataria Multiflora) to make antibacterial food packaging paper

Some medicinal herb extracts have the antibacterial capability. On the other hand, herb extract is one of the organic, natural, and environmentally friendly substances. In recent years, the production of environmental and safe packaging materials has attracted the attention of scientists and industrialists. Paper is one of the biodegradable and less cost options for packaging in various industries, including the food industry. Also, the raw materials of paper can be modified and changed with different materials. As a result, paper fibers can be treated with herb extracts and used in the production of renewable papers with antibacterial properties.

In this research, thyme (Zataria Multiflora) was used for extraction. The thyme obtained from the research farm was dried and then powdered. Powdered thyme was treated via ultrasonication. In this method, two amplitudes of 40 and 60 amplitudes and three time levels of 3, 6, and 9 minutes were used for extraction. Then the papers were treated with herbal extract prepared in two amounts of 15 and 20% based on the dry weight of the paper by spraying. The antibacterial properties of the papers were investigated with Escherichia coli and Staphylococcus aureus bacteria. The chemical structure of materials extracted from the thyme extract investigated by fourier transform infrared spectrum (FTIR) analysis. Also, gas chromatography (GC-MASS) analysis was used to investigate the components of thyme extract. The optical properties of the paper, including brightness and opacity, and the strengths properties of the produced papers were measured by tensile, tear, and burst strengths.

The highest inhibition zone diameter in the treated paper with the thyme extracted by ultrasonic method was 20 mm in 40 amplitude and 9 minutes for Escherichia coli bacteria. Also, the highest inhibition zone diameter for Staphylococcus aureus bacteria was 14 mm in 60 amplitude and 6 minutes. According to the results of the papers analysis, the papers showed better antibacterial properties and higher inhibition zone against the Escherichia coli bacteria. The chemical compounds in the thyme extract including various substances such as hexane and furans. The most important chemical components that caused the antibacterial properties of the papers is carvenone, which was observed in the thyme extract. The results of the strength test of the treated papers showed that the sample of the thyme extracted by the ultrasonic method at 40 amplitudes, 3 minutes, and the 20% consumption amount based on the dry weight of the paper has the highest tensile and burst index. As well as, the highest tear index of the treated papers was in the treated sample with the thyme extracted at 60 amplitudes, 3 minutes, and 15% consumption amount based on the dry weight of the paper. The results of the optical tests showed that the opacity of the papers decreased and the brightness increased.

The results of this research showed that the paper as a biodegradable and environmentally friendly material has the ability to be treated with herbal and natural antibacterial materials such as the thyme extract. Also, the herbal extracts are a suitable alternative to inorganic and metallic materials in the production of materials with antibacterial properties due to the herbal extracts are cheap, available and natural materials.