In this study, essential oil and various extracts (hexane, petroleum ether, acetone, ethanol, methanol and water) of Eucalyptus gilii were screened for their chemical composition, antimicrobial and antioxidant activities. The essential oil chemical composition was analyzed by gas chromatography-mass spectrometry (GC-MS) and gas chromatography-flame ionization detection (GC-FID), respectively. Thirty four compounds were identified, corresponding to 99.5% of the total essential oil. Tannins [104.9–251.3 g catechin equivalent (CE)/Kg dry mass], flavonoids [3.3–34.3 g quercetin equivalent (QE)/Kg dry mass], phenolics [4.7–216.6 g gallic acid equivalent (GAE)/Kg dry mass] and anthocyannins [1.2–45.3 mg cyanidin-3-glucoside equivalent (C3GE)/Kg dry mass] of various extracts were investigated. Free radical scavenging capacity of all samples was determinedt. In the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay, the IC₅₀ of essential oil was 163.5 ± 10.7 mg/L and in the 2,2'-azinobis-3-ethylbenzothiazoline-6-sulphonate (ABTS) assay, it was 94.7 ± 7.1 mg/L. Among the various extracts, the water extract showed the best result (IC₅₀ = 11.4 ± 0.6 mg/L) in the DPPH assay which was comparable to vitamin C (IC₅₀ = 4.4 ± 0.2 mg/L). The antimicrobial activities were evaluated against different bacterial and fungal strains. Gram positive bacteria were found to be more sensitive to the essential oil and extracts than Gram negative ones. Anthocyanins seem to have a major effect on the growth of Bacillus subtilis (R² = 0.79). A significant antifungal activity was observed against the yeast and fungi. Correlations between chemical composition and antioxidant activities were studied and R² values were about 0.96 for the effect of phenolics on the DPPH assay.

This study is aimed at identifying the chemical composition of the essential oil extracted from the Syzygium aromaticum seeds, as well as investigating its biological activities, insecticide effect, and allelopathic properties. The extraction yield was about 14.3 and 7.14% for grounded and ungrounded seeds, respectively. The GC‐MS analysis allowed the identification of 17 heterogeneous compounds, including eugenol (68.7‐87.4%), as major compound, cyperene (20.5‐7.2%), phenethyl isovalerate (6.4‐3.6%), and cis‐thujopsene (1.9‐0.8%), respectively, for grounded and ungrounded seeds. Concerning the antibacterial activity, the diameter of the inhibition zone reached 35 mm when the essential oil extracted from grounded seeds was applied against Escherichia coli. Regarding the antioxidant activity via the DPPH radical scavenging test, the IC₅₀ varied from 1.2 ± 0.1 to 2.8 ± 0.5 μg/mL. With respect to reducing power, the efficient concentration EC₅₀ ranged from 32 to 50 μg/mL. The essential oil exhibited also an allelopathic effect against seeds of Hyoscyamus niger, as well as an insecticide effect against Sitophilus oryzae with a DL₅₀ value of 252.4 μL/L air. These findings enhance the use of this spice as a natural food preservative and encourage its use in several fields, including pharmaceutical, cosmetics, agriculture, and therapy, that could be a strategic way to guarantee the consumer’s health.

This study gives a new insight into the direct supplementation of Allium roseum leaves in double cream cheese. Allium roseum leaves were added to double cream cheese as a powder and a fresh paste. Based on the formulation calculation and on sensory analyses, doses of 6% paste and 0.8% powder were used to formulate the flavored cheeses. The sensory characteristics of the two double cream cheeses were assessed and compared to a plain formula. Cheese samples, stored at 5 °C, were sampled every 0, 4, 8, 12 and 15 days and analyzed for pH, fat, dry contents, yeasts and molds and total coliforms. The positive effects of Allium roseum supplementation, either as a powder or as a fresh paste, have been proven, based on sensorial, physicochemical, and microbiological qualities. The shelf life of cheese samples was also determined through an accelerated shelf life test and the Arrhenius equation. The experiments were conducted at 5, 15, and 25 °C for 15 days. The results showed a significant shelf life extension for flavored double cream cheeses (12 days) versus the plain formula (10 days). The use of Allium roseum leaves, as a natural preservative, seems to be a promising trend for the formulation of similar dairy products.

Journal of Medical and Bioengineering (JOMB)