In this work, an analytical method for the determination of the 16 polycyclic aromatic hydrocarbons (PAHs), classified as priority pollutants by the US Environmental Protection Agency (EPA), on bitter orange leaves has been optimised and validated. The method has been applied to the evaluation of the applicability of leaves of bitter orange tree as a bioindicator of urban atmospheric pollution by these contaminants. Leaves of bitter orange trees were collected from 13 sampling points in Seville city (South of Spain). Sampling points were located in high-density traffic streets (n = 5), in low-density traffic streets (n = 5) and in urban parks (n = 3). Fourteen of the 16 PAHs monitored were detected in bitter orange leaves. The highest mean concentrations corresponded to BaA, Phen, Pyr and Flt. The concentrations in high-density traffic streets were similar to those in low-density traffic streets. Lower concentrations were found in leaves from parks. PAH diagnostic ratios were applied to identify and to assess pollution emission sources. Diagnostic ratios obtained were consistent with traffic emissions as the main source of PAH to urban air. Based on the obtained results, leaves from bitter orange trees appears to be a promising inexpensive passive sampler suitable for extensive sampling in time and space that can be applied to evaluate risk assessment of urban population to PAH air pollution.

This work reports the production of activated carbons (AC) from bitter orange peel by using ZnCl₂ or H₃PO₄ as activating agent at two different carbonization temperatures (450 °C and 550 °C). Surface morphology analyses of produced bitter orange activated carbons (BOACs) were done by SEM. The surface areas of the produced BOACs, functional groups on the AC surfaces and compositions, were determined by using BET, FT-IR, and TGA analyses. Furthermore, their application for the removal of methylene blue (MB) was studied. The parameters affecting adsorption, such as pH and temperature, were evaluated. BOAC produced with ZnCl₂ at 550 °C, exhibits the highest surface area (1450.6 m² g⁻¹), whereas BOAC produced with ZnCl₂ at 450 °C yielded with the highest adsorption capacity (108.9 m² g⁻¹). Langmuir isotherm shows a good fit for the BOACs. Adsorption kinetics were studied and follows pseudo-second-kinetic model. The thermodynamic parameter studies indicate that the adsorption process is endothermic and spontaneous.

Food contamination by aflatoxin B1 (AFB1), produced by mycotoxigenic strains of Aspergillus spp., causes severe medical and economic implications. Essential oils (EOs) are mixtures of eco-friendly natural volatile substances. Their ability to inhibit fungal growth has been investigated, while no data are available about their efficacy in inhibition of AFB1 biosynthesis. This study investigates the efficacy of five different citrus EOs to inhibit the growth and AFB1 synthesis of A. flavus through in vitro tests for a future application in food matrices. AFB1 detection was carried out by LC-ESI-TQD analytical approach. Lemon (Citrus limon (L.) Burm. f.), bergamot (Citrus bergamia Risso), and bitter orange (Citrus aurantium L.) EOs were the most effective causing a 97.88%, 97.04%, and 96.43% reduction in mycelial growth, respectively. Sweet orange and mandarin EOs showed the lowest percentage of mycelial growth reduction. Citrus EOs showed different capacity of AFB1 inhibition (lemon > bitter orange > bergamot > sweet orange > mandarin). Our results showed a dose-dependent antifungal activity of lemon, bitter orange, and bergamot EOs which at 2% (v/v) inhibited both mycelium growth and AFB1 genesis of A. flavus. Our results show that EOs’ use can be a pivotal key to recovery and reuse of citrus fruit wastes and to be used as eco-friendly fungicides for improvement of food safety. The use of EOs obtained at low cost from the residues of citric industry presents an interesting option for improving the profitability of the agriculture.