Antimicrobial activity of chitosan film containing nanocomposite of Trachyspermum ammi (ajwain) seed oil loaded Halloysite nanotubes against foodborne pathogenic microorganisms

Ajwain seed oil (ASO) is a volatile organic compound possessing antimicrobial properties against a wide range of microorganisms. Halloysite nanotubes (Hal) are aluminosilicate natural clay minerals with about 200–2000 nm in length and diameters between 10-50 nm. The structure of Hal allows a sustained release of antimicrobial agents to microbial cells which can be beneficial in the food packaging field. In this work, we loaded ASO into Sodium hydroxide (NaOH) treated Hal and further incorporated it with chitosan to develop an innovative antimicrobial food packaging nanocomposite film. The developed nanocomposite films were characterized by UV–visible spectroscopy, Fourier transform infrared spectroscopy, Raman Spectroscopy, Differential scanning calorimetry, Field emission scanning electron microscopy and X-ray diffraction. The antimicrobial properties of the developed nanocomposites were studied against two bacterial strains (Escherichia coli and Bacillus mojavensis) and two fungus strains (Aspergillus niger and Aspergillus flavus) potential food spoilage microorganisms. The nanocomposite (ASO-NaOH-Hal) prevented the growth of Esherichia coli up to 99%, Bacillus mojavensis up to 95%, Aspergillus niger about 97%, and Aspergillus flavus about 97% at concentrations of 5 mg/ml, 7 mg/ml, 5 mg/ml and 5 mg/ml, respectively. And the chitosan film containing ASO-NaOH-Hal presented a clear zone of inhibition against the above-mentioned bacterial strains and inhibited the growth of fungus on the tomato's surfaces therefore, this nanocomposite film could find application in the food packaging field owing to its antimicrobial and antioxidant properties.