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Citron peel is a valuable by-product gained from the fruit processing industry, which can be utilized as a potential feedstock to extract important commercial compounds such as essential oils. This conversion process can play a main role in reducing pollution and saving the environment by reusing waste, in addition to producing added-value products. In the present study, to extract the essential oil from citron peel were applied various methods of hydrodistillation and supercritical CO2, and the different essential oils produced were evaluated and compared in terms of extraction yield, physical attributes, bioactive compounds, chemical compositions, antioxidant and antimicrobial activity. The results showed that higher amount of extraction yield (7.6%), total phenol (112.84 mg GAE/g), flavonoid compounds (33.38 mg QE/g) and limonene (the major volatile component of citron peel essential oil) (60.69%) belonged to the supercritical CO2sample. The DPPH scavenging activity and reducing power of all the essential oils increased in a concentration-dependent manner (50–2000 µg/mL). The treatments of hydrodistillation and supercritical CO2in the order recorded less and more IC50values in both DPPH and FRAP tests. The obtained data from assay of MIC, MBC and inhibition zone diameter represented that citron peel essential oils possessed the best antimicrobial activity against Staphylococcus aureuscompared to Escherichia coliand Pseudomonas aeruginosa, respectively. Therefore, citron peel essential oil considering the high levels of volatile and bioactive compounds viz limonene, phenol and flavonoid and desirable characteristics of antioxidant and antimicrobial can be used as a natural functional additive in the food industry.

In this research, phytochemical compounds and antioxidant capacity in camelina oil (CMO) were identified through chromatography and spectrophotometry methods and compared with canola (CNO) and sunflower (SNO) oils. The antioxidant potential of the oils was evaluated through DPPH scavenging and the β-carotene bleaching (BCB) methods. Furthermore, fatty acid profiles and some stability indices of the oil were measured. Finally, the correlation coefficients were assessed between the parameters. The results revealed that γ-tocopherol (659.02 mg α-T/kg) and β-sitosterol (2069.6 mg Chol/kg) were the main tocopherol and sterol in CMO, respectively. Tocopherol content in the oils studied did not differe significantly. The highest contents of sterols, carotenoids, and chlorophylls were found in CNO while the highest contents of phenols were found in CMO. CMO and CNO showed the highest DPPH scavenging (IC50of 104.74 ± 1.85 and 123.33 ± 19.32 mg/mL, respectively) and BCB (IC50of 78.41 ± 1.31 and 77.91 ± 5.37 mg/mL, respectively) activities. The peroxide and anisidine values (PV and AnV, respectively) of the oil were found to be in the order of SNO > CMO > CNO, while MUFA:PUFA ratio and the oxidative stability index (OSI) were CNO > CMO > SNO and CNO > SNO > CMO, respectively. The highest correlation of OSI was detected to be with sterol content (r: 0.920) and MUFA:PUFA ratio (r: 0.950) and the highest correlation of IC50of antioxidant capacity assays was found to be with tocopherol content (r > 0.996). Overall, the correlation analyses indicated that in addition to fatty acid profile and level of oil unsaturation, the antioxidant content of cold-pressed oils should be considered to determine oil quality.