Journal Articles

Permanent URI for this collectionhttps://mro.massey.ac.nz/handle/10179/7915

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Start date: 2022Subject: search.filters.subject.Stability

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    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 S
    Natural 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.
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    The effects of ageing treatment on bioactive contents and chemical composition of liquid smoke food flavourings
    (Springer Nature, 2022-05-01) Xin X; Zhao W; Essien S; Dell K; Baroutian S
    Liquid smoke food flavouring is an alternative to traditional food smoking. Ageing treatment of liquid smoke can remove tar to improve a consistent sensory experience but traditionally takes months by storage. This study proposed a thermal treatment approach to accelerate the ageing process. Liquid smoke samples from kānuka and hickory woodchips were prepared by fast pyrolysis. The obtained liquid smoke samples were subjected to ageing by storing them at ambient temperature for 18 months. Accelerated ageing of liquid smoke was carried out by heat treatment at 80 °C for 24 and 48 h. Tar formed during the ageing process, with a yield ranging from 2.2 to 4.1 wt.%. Both ageing treatments resulted in decreases in bioactive content and their activities in terms of total phenolic content (TPC), total flavonoid content (TFC), ferric reducing antioxidant power assay (FRAP) and 2,2-diphenyl-1-picrylhydrazyl scavenging activity (DPPH). Chemical composition and principal component analyses indicated that liquid smoke chemical compositions were influenced by wood type and ageing conditions. It was found that thermal treatment at 80 °C for 24 h was sufficient to age liquid smoke.
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    The physicochemical properties of β-carotene emulsions stabilized by whey protein/octenyl succinic anhydride (OSA)-modified-starch complexes: Influence of OSA substitution degree of starch
    (Elsevier Ltd, 2024-04-01) Lin Q; Yang X; Liu Y; Lu Y; Liu W; Han J; Singh H; Ye A
    Complexes formed between heated whey protein isolate (HWPI) and octenyl succinic anhydride (OSA)-modified starches were prepared to stabilize β-carotene-containing oil-in-water emulsions. The zeta-potential, turbidity, particle size, and microstructure of the complexes were determined to evaluate the impact of the degree of substitution (DS) of OSA-modified starch on the complexes' structure. HWPI and OSA-modified starches with low DS values formed elongated complexes. With increasing DS, the particle size of the complexes reduced. In comparison to the emulsions stabilized by HWPI or OSA-modified starches, the emulsions stabilized by HWPI/OSAS complexes exhibited superior protection of β-carotene during storage under acidic conditions. When the DS of OSA-modified starch increased, the particle size of emulsions stabilized by the complexes decreased, with less droplet aggregation occurring. The physical stability of these emulsions against storage time, ions, and thermal process showed a positive relationship with the DS, while the β-carotene retention in the emulsions during storage showed a negative relationship with the DS. The greater physical stability of the complex-stabilized emulsions containing OSA-modified starch with a higher DS may be ascribed to enhanced electrostatic repulsion among oil droplets and the formation of a more rigid and denser surface structure in the presence of more OSA groups.