The composition of the essential oil depends on the duration and conditions under which the distillation of the plant material is carried out. In this study, one sample without fractionation and eight fractions (each after 15 min of steam distillation) of the essential oil of cultivated H. italicum were analysed by gas chromatography-mass spectrometry (GC-MS). The steam conditions for all samples were as follows: flow rate 800 L/h, temperature 104 °C, and pressure 0.4 bar. The test of the antimicrobial activity was performed with the modified Kirby–Bauer method (disc diffusion method) on non-selective nutrient media (blood agar) using the reference bacterial and fungal strains. A total of 75 different components were found in the essential oil samples obtained. A shorter distillation time makes the oil richer in monoterpenes and more suitable for the perfume and cosmetics industry. On the other hand, prolonged distillation leads to the essential oil being enriched with sesquiterpene oxides, which can have a negative effect on the fragrance of the essential oil. The essential oil of H. italicum showed antimicrobial activity only against Staphylococcus aureus ATCC 25923, and the best activity was shown by the sixth fraction.

The composition of an essential oil (EO) depends on both the plant’s genetic constitution and environmental factors. In this study, the leaves of female bay laurel (Laurus nobilis L., family Lauraceae) plants were collected each month in the period from 15 January to 15 December 2022. Twelve obtained leaf samples were hydrodistilled in a Clevenger apparatus and analyzed using gas chromatography–mass spectrometry (GC-MS). A total of 44 compounds were detected in EO and 39 compounds were identified based on MS spectra and RIs (retention indices), accounting for 99.44–99.94% of the oil. The EO consisted almost entirely of monoterpenes (95.56–99.28%) and small quantities of phenylpropanoids, sesquiterpenes and other compounds. The major volatile compound was 1,8-cineole (49.79–64.94%), followed by α-terpinyl acetate (7.14–11.96%), sabinene (3.16–9.01%), linalool (1.77–8.03%), α-pinene (1.46–4.49%), β-pinene (1.55–3.69%) and α-terpineol (0.99–4.77%). The ANOVA indicated statistically significant changes in the composition of the EO over one year. The contents of eugenol, methyl eugenol and elemicin, which are responsible for the spicy aroma of the leaves, were highest during flowering (March) and at the time of fruit ripening (October, November). The harvest time of the leaves can be adjusted to obtain leaves rich in the desired compounds according to whether they are to be used as a spice, medicine or repellent.

This study reports the effective reuse of coffee residues from roasting and brewing processes using microwave-assisted extraction (MAE) of bioactive compounds. Principal Component Analysis (PCA) showed a significant impact (p < 0.001) on phenolic acid and alkaloid amounts among coffee (green and roasted) and its by-products (silver skin and spent grounds). Furthermore, a linear mixed-effects model identified that, apart from sample type, extraction temperature (50 and 70 °C) and ethanol volume fractions (50 and 70%, v/v) considerably influenced the quantities of bioactive compounds. The best conditions were achieved using 70% (v/v) ethanol at 70 °C. In addition to caffeine and chlorogenic acid, which were found in the highest amounts, the coffee and by-product samples contained high levels of total fibre (20.7–27.8%) and total fat (1.5–12.4%). Fatty acid analysis showed a dominance of oleic acid (7.55–12.7%), palmitic acid (19.3–40.3%), and linoleic acid (15.6–41.8%), with their saturated and unsaturated nature confirmed by Fourier Transform Infrared (FTIR) Spectroscopy. The reported data highlight the potential of coffee by-products as high-value sources for bioactive compound recovery.

Bay laurel (Laurus nobilis L., Lauraceae) is an important Mediterranean aromatic species widely used as a culinary spice and a source of bioactive constituents. This study aimed to evaluate the essential oil (EO) composition, macronutrient content, polyphenolic profile and antioxidant activity of bay laurel along the Croatian Adriatic coast. A total of 49 volatile compounds were identified in dried leaves using GC–MS, representing 99.27–100.00% of the EO composition. The EOs were dominated by oxygenated monoterpenes (86.51–95.55%), with 1,8-cineole (42.40–56.83%), α-terpinyl acetate (6.89–12.76%), sabinene (6.10–8.65%), linalool (2.06–14.46%), and methyl eugenol (0.45–10.10%) as the major constituents. Polyphenolic profile obtained by spectrophotometric methods showed that total polyphenol content ranged from 6.03% to 9.65%, tannins from 1.81% to 4.76%, flavonoids from 0.23% to 0.71%, and total phenolic acids from 1.34% to 3.03% (rosmarinic acid equivalents) and 2.51% to 5.66% (chlorogenic acid equivalents). Furthermore, we highlighted the antioxidant activity of Croatian bay laurel using the 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH), and ferric reducing antioxidant power (FRAP) assays. Ethanolic extracts exhibited higher antioxidant activity than aqueous extracts, reaching 74.58–82.03% ABTS inhibition and 57.93–69.54% DPPH inhibition. This study provides the first integrated characterization of Croatian bay laurel leaves and highlights their antioxidant potential.