Journal Articles
Permanent URI for this collectionhttps://mro.massey.ac.nz/handle/10179/7915
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Item Characterization, antibacterial activity, and stability of supercritical fluid extracted lemongrass nanoemulsion on Bacillus cereus(Elsevier Ltd, 2025-06) Mohd Daud IS; Mahmud Ab Rashid NK; Palmer J; Flint SNatural food preservation is a sustainable approach to extend shelf life, combat foodborne pathogens and enhance food safety. Bacillus cereus, a resilient contaminant, poses challenges due to its spore-forming ability and association with foodborne illnesses. This study investigates the characterization, antimicrobial activity, and stability of lemongrass (Cymbopogon citratus) nanoemulsions, extracted using supercritical fluid extraction (SFE), and their efficacy against B. cereus isolates (ATCC 14579, P4, and M2). Lemongrass oil was extracted at 85, 100, 200, and 300 bar, with the highest yield (0.815 %) obtained at 300 bar. Nanoemulsions were formulated with lemongrass extract and commercial citral, characterized for droplet size, polydispersity index (PDI), conductivity, and zeta potential, and assessed for antimicrobial activity. Lemongrass nanoemulsions initially had droplet sizes of 86.32 ± 0.66 nm, but increased over six months due to coalescence, with PDI values rising from 0.50 ± 0.00 to 0.81 ± 0.27, indicating reduced stability. Although zeta potential declined from −44.01 ± 1.69 mV to −33.63 ± 1.45 mV, it remained within the stable range (>±30 mV), maintaining sufficient electrostatic repulsion to prevent rapid aggregation. At 2.0 % concentration, nanoemulsions effectively suppressed B. cereus isolates (<1.00 CFU/mL), though efficacy declined after four months with increasing droplet size. Lemongrass nanoemulsions exhibited comparable antibacterial activity and stability trends to citral, suggesting that whole lemongrass extract retains its bioactivity as effectively as its major compound. Improved stabilization strategies, such as polymer encapsulation, could enhance shelf life, expanding applications in food preservation.Item Edible films from essential-oil-loaded nanoemulsions: Physicochemical characterization and antimicrobial properties(1/05/2015) Acevedo-Fani A; Salvia-Trujillo L; Rojas-Graü MA; Martín-Belloso OEdible films including active ingredients can be used as an alternative to preserve food products. Essential oils (EOs) exhibit antimicrobial activity against pathogenic microorganisms but their low water solubility limits the application in foods. To improve water dispersion and protect EOs from degradation, nano-sized emulsions emerge as a viable alternative. Nanoemulsions containing EOs and polysaccharides could be used to form edible films with functional properties. This study was focused on the evaluation of physical, mechanical and antimicrobial properties of alginate-based edible films formed from nanoemulsions of EOs. Nanoemulsions containing thyme (TH-EO), lemongrass (LG-EO) or sage (SG-EO) oil as dispersed phase and sodium alginate solution as continuous phase were prepared. The average droplet size of nanoemulsions was reduced after the microfluidization treatment exhibiting multimodal size distributions. The ζ-potentials of nanoemulsions were between-41mV and-70mV depending on the type of EO used. The lowest whiteness index was found in SG-EO nanoemulsions, whereas those containing TH-EO showed the highest value. Films formed from SG-EO nanoemulsions exhibited higher transparency, water vapor resistance and flexibility than films formed from TH-EO or LG-EO. Edible films containing TH-EO were those with the strongest antimicrobial effect against inoculated Escherichia coli, achieving up to 4.71Log reductions after 12h. Results obtained in the present work evidence the suitability of using nanoemulsions with active ingredients for the formation of edible films, with different physical and functional properties.
