Antioxidant Film with Chitosan and Essential Oils for Preserving Walnuts

Jim Crocker
21st August, 2024

Antioxidant Film with Chitosan and Essential Oils for Preserving Walnuts

Image Source: Natural Science News, 2024

Key Findings

  • The study from the Indian Institute of Technology Roorkee found that adding Tulsi essential oil to chitosan films made them less transparent and more moisture-resistant
  • Adding Ajwain essential oil alongside Tulsi increased the films' moisture content, swelling capacity, and water solubility, counteracting some effects of Tulsi oil
  • The combination of Tulsi and Ajwain oils significantly enhanced the antioxidant activity of the chitosan films, which is beneficial for extending the shelf life of food products
Chitosan, a biopolymer derived from chitin, has garnered attention for its potential applications in the biomedical and food packaging industries due to its biocompatibility and biodegradability. However, its inherent properties often require modification to enhance its functionality. A recent study conducted by the Indian Institute of Technology Roorkee[1] investigates the impact of incorporating a blend of essential oils from Tulsi (holy basil) and Ajwain (Trachyspermum ammi) into chitosan films, aiming to improve their physiochemical properties and antioxidant activity. The study found that incorporating the essential oil blend into chitosan films led to noticeable changes in transparency, moisture content, swelling capacity, and water solubility. Specifically, the addition of Tulsi essential oil alone decreased these properties, making the films less transparent and more moisture-resistant. However, when Ajwain essential oil was added alongside Tulsi, there was a significant increase in moisture content, swelling capacity, and water solubility. This suggests that Ajwain oil counteracts some of the effects of Tulsi oil, likely due to differences in their chemical compositions. The mechanical properties of the films were also affected. The tensile strength, which measures how much force a material can withstand while being stretched, increased from 14.95 MPa to 31.27 MPa with the addition of Tulsi essential oil. However, further increasing the concentration of Ajwain oil resulted in a decrease in tensile strength from 32.13 MPa to 15.89 MPa. On the other hand, the percent elongation at break, which indicates the film's flexibility, increased from 8.26% to 24.02% due to Ajwain oil's plasticizing effect. This dual effect of Ajwain oil both weakening and making the film more flexible is crucial for applications requiring a balance between strength and flexibility. The antioxidant activity of the films was another focal point of the study. Tulsi essential oil-containing films exhibited antioxidant properties that were significantly enhanced with the addition of Ajwain essential oil. This is particularly relevant for food packaging, as antioxidants can prevent the oxidation of fats and oils, thereby extending the shelf life of food products. The study confirmed the effectiveness of these films by packing walnuts in the active film, which demonstrated better antioxidant activity against oil oxidation in walnuts. This was verified using Fourier Transform Infrared Spectroscopy (FTIR), a technique that measures how infrared light is absorbed by a material, indicating chemical changes. Previous studies have explored the properties and applications of essential oils and chitosan separately. For instance, the essential oil from Ajwain seeds has been analyzed for its chemical composition and biological activities[2]. Thymol, a major component of Ajwain oil, has been noted for its antimicrobial and antioxidant properties. This aligns with the current study's findings, where the addition of Ajwain essential oil improved the antioxidant activity of chitosan films. Another study evaluated the antioxidant capacity of chitosan and its interference in the formation of calcium oxalate crystals[3]. It was found that chitosan itself showed low antioxidant activity but had excellent copper-chelating activity. The current study builds on this by demonstrating that the antioxidant properties of chitosan can be significantly enhanced by incorporating essential oils, particularly those rich in bioactive compounds like thymol. Furthermore, the use of essential oils in food preservation has been previously explored. For example, a study on the microencapsulation of holy basil essential oil aimed to protect it from volatilization and oxidation[4]. The microencapsulation technique improved the retention and antioxidant activity of the essential oil, which is similar to the current study's approach of blending essential oils with chitosan to enhance its properties. In summary, the study from the Indian Institute of Technology Roorkee demonstrates that incorporating a blend of Tulsi and Ajwain essential oils into chitosan films significantly alters their physiochemical properties and enhances their antioxidant activity. This research provides a promising approach to developing active packaging materials that can extend the shelf life of food products while maintaining their quality. The findings also build on previous studies, showing that the combination of chitosan and essential oils can lead to multifunctional materials with potential applications in various industries.

HerbsBiochem

References

Main Study

1) Physicochemical characterization of antioxidant film based on ternary blend of chitosan and Tulsi-Ajwain essential oil for preserving walnut.

Published 18th August, 2024

https://doi.org/10.1016/j.ijbiomac.2024.134880

Related Studies

2) Thymol screening, phenolic contents, antioxidant and antibacterial activities of Iranian populations of Trachyspermum ammi (L.) Sprague (Apiaceae).

https://doi.org/10.1038/s41598-022-19594-7

3) Does the use of chitosan contribute to oxalate kidney stone formation?

https://doi.org/10.3390/md13010141

4) Optimisation of microencapsulation of holy basil essential oil in gelatin by response surface methodology.

https://doi.org/10.1016/j.foodchem.2013.10.159


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