Antioxidant and antimicrobial efficacy of microencapsulated mustard essential oil against Escherichia coli and Salmonella Enteritidis in mayonnaise.

The aim of this study was to investigate the effect of pure and encapsulated mustard essential oil (MEO) on the shelf life of mayonnaise and its ability to be an alternative for synthetic preservatives. Determination of the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) indicated higher sensitivity of Escherichia coli O157:H7 (E. coli O157:H7) (MIC: 512 ppm, MBC: 1024 ppm) than Salmonella Enteritidis (S. enteritidis) (MIC: 1024 ppm, MBC: 2048 ppm) to MEO. Mayonnaise samples, were subsequently prepared according to the determined MIC and MBC of MEO for microbial analysis and physicochemical analysis. The antimicrobial activity of MEO in mayonnaise over 40-day storage indicated that the application of free and encapsulated MEO could inhibit the growth of target bacteria. In addition, the oxidative stability of mayonnaise samples exhibited decreasing trends over the storage time. At the end of the storage, the control sample without any preservatives revealed the highest peroxide value (3.59 meq O2 /kg of oil) whereas the sample containing 4096 ppm encapsulated MEO (2 meq O2/kg of oil) exhibited better oxidative stability, following t-butyl-hydroxyquinone (TBHQ) (1.84 meq O2 /kg of oil) as commercial antioxidant. Interestingly, the application of 2048 and 4096 ppm encapsulated essential oil had no undesirable effect on overall acceptance of mayonnaise, while the application of pure MEO at the same concentrations negatively affected the color, odor, taste and overall acceptability.

Tomato seed oil-enriched tomato juice: Effect of oil addition type and heat treatment on lycopene bioaccessibility and oxidative stability.

In this study, tomato seed oil conventional emulsion (7 µm) and nanoemulsion (0.146 µm) with desirable stability were prepared, then the effect of tomato seed oil addition (bulk and emulsified forms) and thermal treatment on properties of tomato juice was evaluated. Tomato juice without oil and heat treatment exhibited the lowest bioaccessibility of lycopene (17.8 %). Incorporation of oil and applying heat treatment significantly increased the extent of lipid digestion and bioaccessibility of lycopene. In this regard, the nanoemulsion had the highest bioaccessibility (44.85 %) compared to conventional emulsion (33.90 %) and bulk oil (27.11 %), due to the smaller oil droplets. The oxidative stability of oil in heat-treated tomato juice samples decreased during 28 days of storage at 4 °C, whereas the nanoemulsion exhibited the highest peroxide value (4.43 meq O2/kg of oil) compared to conventional emulsion and bulk oil (3.91 and 3.49 meq O2/kg of oil, respectively) at the end of the period.