Journal Articles

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    Effectiveness of mānuka and rosemary oils as natural and green antioxidants in wagyu and normal beef
    (John Wiley and Sons Ltd on behalf of Institute of Food, Science and Technology (IFSTTF), 2023-02-28) Kaur R; Kaur L; Gupta TB; Bronlund J
    Essential oils possessing antioxidant characteristics have acquired broad interest as an alternative to synthetic food antioxidants like butylated hydroxytoluene (BHT). In this study, mānuka (with 5, 25 and 40% triketone content) (MO), rosemary (RO) and kānuka (KO) oils were characterised and screened through DPPH (2,2-diphenyl-1-picrylhydrazyl) and FRAP (Ferric radical absorbing power) assays for their antioxidant efficacies. Different triketone levels were selected to examine their effect on the antioxidant activity of MO. All MOs showed higher phenolic content and antioxidant activities than KO and RO. Based on the obtained results, the MO with 25% triketone content and RO were chosen to study their antioxidant effects in pastes prepared from New Zealand normal (3% fat) and wagyu (12% fat) beef during refrigerated storage (7 days). No significant effect of the oils was observed on lipid oxidation in normal pastes during storage. However, MO and BHT significantly reduced lipid oxidation in wagyu pastes, showing the potential of mānuka oil as a natural antioxidant in high-fat meat products.
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    Mānuka Oil vs. Rosemary Oil: Antimicrobial Efficacies in Wagyu and Commercial Beef against Selected Pathogenic Microbes
    (MDPI (Basel, Switzerland), 2023-03-21) Kaur R; Kaur L; Gupta TB; Bronlund J; Monteils V; Gagaoua M
    Essential oils possessing antimicrobial characteristics have acquired considerable interest as an alternative to chemical preservatives in food products. This research hypothesizes that mānuka (MO) and kānuka (KO) oils may possess antimicrobial characteristics and have the potential to be used as natural preservatives for food applications. Initial experimentation was conducted to characterize MOs (with 5, 25, and 40% triketone contents), rosemary oil (RO) along with kanuka oil (KO) for their antibacterial efficacy against selected Gram-negative (Salmonella spp. and Escherichia coli), and Gram-positive (Listeria monocytogenes and Staphylococcus aureus) bacteria through disc diffusion and broth dilution assays. All MOs showed a higher antimicrobial effect against L. monocytogenes and S. aureus with a minimum inhibitory concentration below 0.04%, compared with KO (0.63%) and RO (2.5%). In chemical composition, α-pinene in KO, 1, 8 cineole in RO, calamenene, and leptospermone in MO were the major compounds, confirmed through Gas-chromatography-mass spectrometry analysis. Further, the antimicrobial effect of MO and RO in vacuum-packed beef pastes prepared from New Zealand commercial breed (3% fat) and wagyu (12% fat) beef tenderloins during 16 days of refrigerated storage was compared with sodium nitrate (SN) and control (without added oil). In both meat types, compared with the SN-treated and control samples, lower growth of L. monocytogenes and S. aureus in MO- and RO- treated samples was observed. However, for Salmonella and E. coli, RO treatment inhibited microbial growth most effectively. The results suggest the potential use of MO as a partial replacement for synthetic preservatives like sodium nitrate in meats, especially against L. monocytogenes and S. aureus.