Laurel, Laurus nobilis L. is an evergreen plant belonging to the Lauraceae family, native to Southern Europe and the Mediterranean area. This is the first report on the composition and bioactivity of laurel essential oil (EO) from Bulgaria. The oil yield was 0.78%, 0.80%, and 3.25% in the fruits, twigs, and leaves, respectively. The main constituents in the fruit EO were 1,8-cineole (33.3%), α-terpinyl acetate (10.3%), α-pinene (11.0%), β-elemene (7.5%), sabinene (6.3%), β-phellandrene (5.2%), bornyl acetate (4.4%), and camphene (4.3%); those in the twig EO were 1,8-cineole (48.5%), α-terpinyl acetate (13.1%), methyl eugenol (6.6%), β-linalool (3.8%), β-pinene (3.4%), sabinene (3.3%) and terpinene-4-ol (3.3%); and the ones in the leaf EO were 1,8-cineole (41.0%), α-terpinyl acetate (14.4%), sabinene (8.8%), methyl eugenole (6.0%), β-linalool (4.9%), and α-terpineol (3.1%). The antibacterial and antifungal properties of laurel EOs were examined according to the agar well diffusion method. The leaf EO showed antibacterial and antifungal activities against almost all strains of the microorganisms tested, whereas the twig EO was only able to inhibit Staphylococcus aureus. Pseudomonas aeruginosa ATCC 9027 and Escherichia coli ATCC 8739 were the bacterial strains that showed the highest resistance to the laurel EO. The results can benefit the EO industry and biopesticide development.

The chemical composition of Vitex agnus-castus L. (Verbenaceae family) fruits, collected from two regions in Bulgaria (south-central and north-east Bulgaria), was investigated. The content of proteins (5.3–7.4%), carbohydrates (73.9–78.8%), fiber (47.2–49.9%), ash (2.5–3.0%), essential oils (0.5%), and vegetable oil (3.8–5.0%) were identified in the fruits. The composition of the essential oils (EOs) of Vitex fruits from both regions was determined; the main compounds were 1,8-cineole (16.9–18.8%), α-pinene (7.2–16.6%), sabinene (6.7–14.5%), and bicyclogermacrene (7.3–9.0%), but significant differences in the quantitative and qualitative composition of EOs between the regions were found. The EOs of plants from north-east Bulgaria demonstrated antimicrobial activity against the pathogenic species Salmonella abony, Staphylococcus aureus, and Bacillus subtilis, but the Gram-negative bacteria Esсherichia coli and Pseudomonas aeruginosa exhibited resistance to the oil. Linoleic acid predominated in vegetable oil from both regions, followed by oleic acid. β-sitosterol and γ-tocopherol were the main components in the sterol and tocopherol fraction of the lipids. Phosphatidic acids were the main components in the vegetable oil from north-east Bulgaria, while in the vegetable oil from south-central Bulgaria, all phospholipids were found in almost the same quantity. Overall, significant differences were observed in the chemical composition (proteins, carbohydrates, ash and moisture) of the fruits from the two regions of Bulgaria, as well as in the content of the main components of their essential and vegetable oils.

Based on many years of experience, packaging is considered as an inactive barrier that protects materials and goods from environmental factors. The applicability of native chemical additive such as essential oils in wrapping papers can be used in the forms of films, treatments, coatings or others. Essential oils or extracts from different aromatic plants are used as bioactive substances for antimicrobial activity. In this research, lavender essential oil treatment of packaging papers is examined for its inhibition activity under nine microorganisms—two Gram-positive bacteria, three Gram-negative bacteria, two yeast and two fungal strains. The effectiveness of the treatment on the structural and strength indicators of the obtained paper samples is monitored. In detail, a five-day examination is conducted on the antibacterial effectiveness of lavender essential oil treatment. Results indicate that the lavender treatment of the obtained packaging paper is successful and the antifungal effect is more pronounced. The antimicrobial efficiency of paper treated with lavender essential oil is between 60 and 90% in the first two hours after treatment and gradually decreases to 40%–50% at the end of the 120 h period. The lavender essential oil treatment of wrapping paper has a promising perspective for preserving products from microbial spoilage and extending their shelf life.

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.

Fennel (Foeniculum officinale Mill. var. dulce Mill) is an annual aromatic plant of the Lamiaceae family. Its fruits are processed to obtain essential oil for use in the food industry and cosmetics. The physical parameters of the fruits, i.e. length (5.50–8.00 mm), width (1.50–2.00 mm), volume of 100 fruits (1.36 × 10⁻⁶ m³), density of 100 fruits (935.82 kg/m³), average volume of one fruit (1.36 × 10⁻⁸ m³), average equivalent diameter of one fruit (2.96 mm), angle of repose, stainless steel (from 16 to 22°), angle of repose, black steel (from 19 to 28°), angle of repose, plywood (from 18 to 24°), and their chemical parameters, i.e. moisture (13.49%), ash (6.49%), protein (18.25%), essential oil (8.38%), vegetable oil (10.52%), and total carbohydrates (51.04%) were determined for the fruits. The adsorption and desorption isotherms of the fennel fruits were obtained using the static gravimetric method at two temperatures, 20 and 40 °C. The Halsey model provided a good description of the sorption isotherms, which were of type II according to Brunauer's classification. The increase in the temperature led to a significant decrease in the monolayer moisture. The contamination on the fruit surface at three relative humidities (0.43, 0.59, and 0.76) at 20 °C was determined.

Corrosion worldwide causes large losses of metal, which is why various ways are being sought to slow it down. The aim of this study was to investigate the inhibitory effect of fennel fruit essential oil (Foeniculum vulgare Mill.) and its main component anethole. The inhibitory effect of three different concentrations of the fennel essential oil and anethole (1.0 mL/L, 1.5 mL/L, and 2.5 mL/L) in a solution of 1 M HCl at 298 K for 6 h on a sheet of low-carbon steel was investigated. The inhibitory effect was established using gravimetric methods evaluating weight loss, corrosion rate, and inhibition efficiency, as well as electrochemical methods. In gravimetric studies, the inhibition effect of the inhibitors fennel essential oil and isolate anethole at a concentration of 2.0 mL/L was 70.85% and 45.86%, respectively. The anodic polarization curve data at 298 K demonstrate that the anethole and fennel essential oil adsorption on the metal surface creates a barrier that hinders hydrogen ions’ access and prevents them from being reduced on the steel surface’s cathode sites. Fennel essential oil acting as a mixed type-inhibitor can replace synthetic organic substances and could become an alternative to be used as environmental corrosion inhibitors.