Encapsulation of Tunisian thyme essential oil in O/W nanoemulsions: Application for meat preservation.

This study aims to optimize the preparation of thyme essential oil nanoemulsion using a ternary mixture design based on the following three components: chitosan, gum Arabic and median-chain triacyglycerols (MCT). The results showed that the formulation which contained 40% chitosan, 40% gum Arabicand 20% of MCT led to a stable nanoemulsion within 30 days of storage at 4 °C. Indeed, the observed mean diameter (d[4,3]) and the polydispersity index (PDI) are the lowest with a ζ-potential value greater than +30 mV. Moreover, the amount of thyme essential oil dissolved in MCT was optimized and the 2% (w/w) was selected to prepare O/W nanoemulsion for preserving meat products. Besides, the obtained data of the chemical characteristics of meat products demonstrated that the pH, TVNB, TBARS, shear strength increased slightly and insignificantly with storage time at 4 °C.However, there was a difference between control and sample treated with nanoemulsionsin terms of physicochemical characteristics.

Drying methodology effect on the phenolic content, antioxidant activity of Myrtus communis L. leaves ethanol extracts and soybean oil oxidative stability.

In this study, different drying methodologies (convective air, oven and microwave) of Myrtus communis L. (M. communis L.) leaves were conducted to investigate their effects on the levels of phenolic compounds, antioxidant capacity of ethanolic extracts (EEs) as well as the soybean oil oxidative stability. Drying methodology significantly influenced the extractability of phenolic compounds. Microwave drying led to an increase in the amounts of total phenols, flavonoids and proanthocyanidins followed by oven drying at 70 °C. Higher temperature of drying (100 and 120 °C) led to a significant reduction of their amounts (p < 0.05). An ultra-performance liquid chromatography method combined with high resolution mass spectroscopic detection was used to analyze the phenolic fraction of extracts. Higher amounts of the identified compounds were observed when leaves were heat treated. Furthermore, the evaluation of the antioxidant activity showed that the studied extracts possess in general high antioxidant capacities, significantly dependent on the employed drying methodology. The incorporation of the different extracts at 200 ppm in soybean oil showed that its oxidative stability was significantly improved. Extracts from leaves treated with microwave (EE_MW) and at 70 °C (EE_70) have better effect than BHT. The results of the present study suggest that microwave drying could be useful to enhance the extractability of phenolic compounds and the antioxidant capacity of M. communis L. leaf extract.