Garden thyme (Thymus vulgaris L.) is an annual herbaceous plant of the family Lamiaceae. It can be found both in the wild and as a cultivated plant in Bulgaria. This study is aimed at assessing the garden thyme essential oil composition and antioxidant activities, which were collected from three different areas in Bulgaria. The essential oils were obtained by hydrodistillation and analyzed by gas chromatography–mass spectrometry (GC-MS). The main compounds in the garden thyme essential oils (over 2%) were as follows: thymol (42.88–53.55%), p-cymene (14.25–25.51%), γ-terpinene (6.58–15.51%), borneol (2.75–3.57%), carvacrol (2.00–3.02%), β-linalool (2.07–2.31%), cis-sabinene hydrate (4.05%), eucalyptol (1.08–3.65%), α-terpinene (1.01–3.24%), carvacrol methyl ether (1.18–3.02%), and thymol methyl ether (2.26–3.16%). The oils were mainly composed of oxygenated phenyl propanoids, and all the essential oils belonged to the chemotype thymol. Antioxidant activities were measured by DPPH (2,2-diphenyl-1-picrylhydrazyl radical) and ABTS [2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)] assays. All the samples exhibited antioxidant activity relative to the DPPH radical (from 143.20 mM TE/mL to 165.91 mM TE/mL) and by the ABTS method (from 121.67 mM TE/mL to 127.62 mM TE/mL). These garden thyme essential oils could be used as natural antioxidants for food and as nutraceuticals.

The chemical composition of ethanol extracts from wild and cultivated Bulgarian white oregano (Origanum heracleoticum L.) was determined. It was found that the aromatic compounds are the dominant group in the extracts of wild and cultivated white oregano – 89.75% in both extracts. The main components are carvacrol (70.97%) in the extract of wild oregano and carvacrol (60.47%) and thymol (8.55%) in the extract of cultivated oregano. The antimicrobial activity of aromatic products of Bulgarian white oregano was studied. The antimicrobial activity of the essential oils and ethanol extracts of oregano was determined against bacteria, which are found to be human pathogenic or food spoilage microorganisms – Staphylococcus aureus, Listeria monocytogenes and Escherichia coli ATCC 25922. Both the essential oils and the extracts showed antimicrobial activity against the tested microorganisms, more significant in the wild species, probably due to the high content of carvacrol. Gram-negative bacteria Escherichia coli showed resistance to the extracts, but were affected by the essential oils, the diameters of the zones of inhibition being comparable to those of the antibiotics Gentamicin and Tobradex. The results obtained suggest a potential application of these oils in preventing human pathogenesis and food spoilage due to microorganism growth.

Lavender (Lavandula angustifolia Mill.) fam. Lamiaceae is a cultivated plant in Europe, Asia and the Americas. The aim of present work is study on chemical composition, physicochemical and thermodynamic properties of lavender essential oil from Bulgaria. The main essential oil constituents are linalyl acetate (26.19%), β-linalool (21.39%), β-caryophyllene (6.80%), (Z)-β-ocimene (6.78%), terpinen-4-ol (5.01%), lavandulol acetate (4.39%), (E)-β-ocimene (3.02%), (E)-β-farnesene (2.73%), 1-octen-3-yl-acetate (2.65%), and α-terpineol (2.36%). Physicochemical (refractive index and relative density), thermodynamic (Gibbs energy, enthalpy, entropy, and activation energy) and thermal properties (heat capacity, thermal conductivity, thermal diffusivity, dynamic, and kinematic viscosity) of lavender essential oil and its main components are investigated.

The possibilities for application of essential oils and ethanol extracts of Bulgarian white oregano in the production of cooked-smoked sausages have been studied. In the composition of the sausage product were included essential oils (20 mg/kg) and ethanol extracts (75 mg/kg) from wild and cultivated white oregano. It has been found that adding essential oils and extracts improve the taste of the sausage without changing the appearance and texture of the meat product. The color characteristics on the surface and the inside of the sausage during storage for 24, 48 and 72 hours were determined. No significant changes in color parameters (L*, a* and b*) were established during storage for 72 h. The total microbial count in meat products remains within the permissible limits up to 12 days of their production. The essential oil and the ethanol extract of Bulgarian white oregano are suitable additives for cooked-smoked sausages improving their organoleptic characteristics and duration.