Within the scope of this study, essential oil content and its quality parameters of Batem Fatihi, Navelina, Washington Navel, Valencia Late, and Moro cultivars were evaluated with respect to harvest time and isolation methods. Essential oils were obtained using two methods (hydrodistillation and cold pressing) during four harvest periods of each cultivar. Physico-chemical characteristics of essential oils were evaluated, and the chemical components of the oil were identified via GC-MS/FID. Based on the hydrodistillation data, the essential oil ratios ranged between 1.69–2.85 % in samples. While the effects of cultivar and harvesting time on relative density, refractive index, and optical activity values were not statistically important, the effect of isolation method was important (p < 0.05). Relative densities of essential oils obtained by cold pressing were higher (0.8440) than those obtained by hydrodistillation (0.8402). Additionally, refractive index values of the samples obtained by cold pressing were higher (1.4739) than those obtained by the hydrodistillation method (1.4723). On the other hand, it was observed that the optical activity values of the samples obtained by hydrodistillation were higher (98.20°) than those obtained by cold pressing (95.32°). Chromatographic analysis indicated the presence of 10 compounds in the essential oil. Essential oil compositions also showed some differences on the basis of cultivars, harvesting time, and isolation methods, but these differences generally were not statistically significant. Additionally, there were some differences in determined components with respect to cultivar, harvesting time, and isolation method. The most important component in all analyzed samples was determined to be limonene and it was distributed between 94.9–96.4%. The second highest component was determined as β-myrcene and ranged between 1.9–2.0%. While the effect of isolation method and harvesting time on limonene was not important (p > 0.05), the effect of cultivar was significantly important (p < 0.05). On the other hand, both cultivar and harvesting time effects on β-myrcene content were significantly important. Our results showed that there is a significant variation in some quality parameters of the orange peel essential oils according to cultivar and isolation methods.

In this study, Batem Pınarı, Interdonato, Meyer, and Ak Limon lemon cultivars were studied. Lemon peel's essential oils were obtained by two different methods (hydrodistillation and cold pressing) during four different harvest periods for each cultivar. Essential oil content, density, refractive index, optical activity, and composition were evaluated. The highest essential oil amount was found in the Interdonato cultivar (2.54%) and the lowest in Ak Limon (1.37%). The highest density value was 0.8471 g/mL (Ak Limon) and the lowest was 0.8423 g/mL (Meyer). Essential oil densities obtained by cold pressing were higher than those obtained by hydrodistillation. The highest refractive index values were determined for Batem Pınarı and Meyer (1.4747), and the lowest were determined for Ak Limon (1.4740). The refractive index values obtained by cold pressing were higher than those obtained by hydrodistillation. Optical activity values were found to be highest in Ak Limon and lowest in Batem Pınarı, and higher following hydrodistillation than cold pressing. The essential oil compositions of the samples showed significant differences depending on the cultivar and isolation method. Limonene, the highest component proportionally, composed 76.0%–89.0% of samples. The highest limonene content was determined for Ak Limon (88.7%), and the lowest for Batem Pınarı (76.7%). Limonene content did not change significantly between hydrodistillation (82.2%) and cold press (82.2%) isolation methods. Findings show that there is significant variation in quality parameters of lemon peel essential oils.

Aromatic plant essential oils (EO) and their derivatives are promising, eco-friendly alternatives for fungal disease management in plants due to their low toxicity and environmental compatibility. However, practical applications are often limited by challenges such as high volatility, poor water solubility, and inefficient dispersion. To address these limitations, we developed an innovative approach to enhance the stability and antimicrobial efficacy of Origanum vulgare extracts through the green synthesis of silver nanoparticles (AgNPs). The synthesized AgNPs were characterized using UV-Vis spectroscopy and scanning electron microscopy (SEM). UV-Vis analysis revealed characteristic surface plasmon resonance (SPR) peaks at 445 nm (aqueous AgNPs) and 435nm (methanolic AgNPs), confirming nanoparticle formation. The aqueous extract exhibited the highest total phenolic content (50.3 ± 1 mg gallic acid/g), while methanolic AgNPs demonstrated the strongest antioxidant activity, scavenging 89.7 ± 0.2% of DPPH radicals with an IC₅₀ of 19.6 ± 0.3 µg/cm³. The antifungal activity of O. vulgare essential oil, AgNPs, and crude extracts was evaluated against Aspergillus niger, Botrytis cinerea, and Penicillium expansum. GC-MS analysis identified carvacrol (56.53%), thymol (21.18%), p-cymene (6.22%), and γ-terpinene (5.67%) as the major EO constituents. We are the first to report the green synthesis of AgNPs using O. vulgare extracts with comparative evaluation against crude extracts and essential oils for enhanced antifungal application. This study presents a significant advancement in fungal control strategies by demonstrating that AgNPs synthesized from O. vulgare extracts not only retain the high antifungal and antioxidant properties of the essential oil but also overcome its limitations through improved stability, water solubility, and dispersion. The findings suggest that AgNPs synthesized from O. vulgare are a more effective and sustainable alternative to conventional essential oils for combating fungal pathogens in agricultural and post-harvest applications.

The present study was carried out to prepare thyme essential oil (TEO) and ginger essential oil (GEO)-incorporated edible starch coating on buffalo meat to extend its refrigerated shelf-life. Edible coatings incorporated with antimicrobials can act as an active packaging system for the preservation of meat using biopolymers and plant-based essential oils. Buffalo meat samples were coated by hydrothermally treated starch solution incorporated with thyme and ginger essential oil at five different proportions (total of 2.5% of starch solution). A total of five treatments (S1, S2, S3, S4, and S5) along with two controls (S6 and S7) were subjected to microbiological [total viable count (TVC), Staphylococcus aureus count, psychrotrophic bacteria count (PTC), and coliform count] and physico-chemical analyses such as thiobarbituric acid reactive substance (TBARS) value, total volatile basic nitrogen (TVBN) content, extract release volume (ERV), metmyoglobin (Met-Mb), pH, weight loss, and water activity at 0, 3, 6, 9, and 12 days of storage. These metrics were compared between days and between treatments. Compared with the uncoated control (S7), S4 decreased TVC by 2.60 log, and S5 decreased PTC, Staphylococcus aureus, and coliform by 4.71 log, 1.18 log, and 3.01 log, respectively, in 12 days. S4 reduced TBARS and TVBN by 46.14% and 27.86%, respectively, while S5 increased the ERV by 40.94% in 12 days when compared to S7. Metmyoglobin content, pH, ERV, and TVBN were found to have a high correlation with TVC, while pH was found to have a high correlation with TVBN and ERV. It can be concluded that the increase in TEO concentrations on starch coating increases the ability of buffalo meat to resist microbiological as well as chemical spoilage.