Essential oils (EO) are major products in the world economy. Citrus species (Rutaceae) EO, present in the pericarp of the fruit and leaves, provide raw material for a wide variety of industries such as resin products for paper and textiles, binders to manufacture insecticides, antiseptics, pharmaceuticals, perfumes and food. This study determines the chemical components monoterpenes, sesquiterpenes, plus limonene and linalool enantiomeric distribution of Citrus aurantium Lineu, Citrus sinensis (L.) Osbeck and Citrus reticulata Blanco EO, through gas chromatography coupled with mass spectrometry (GC/MS). All EO were acquired and collected in South and South- Central Brazil. Samples were obtained by steam distillation, hydrodistillation or cold pressing extraction. The results showed that limonene (39.5 to 92.7%) is the main component of the pericarp and linalool (14.2 to 24.8%) is the main component of the leaves. It was shown that the extraction method did not change this distribution. The (R)-(+)-limonene was 60 to 99% in all Citrus EO analyzed. The (R)-(-)-linalool was 59 to 64% in Citrus aurantium and (S)-(+)-linalool was 76 to 99% in Citrus sinensis and Citrus reticulata. The hydrolate of Citrus aurantium (orange water) was also analyzed and presented as the main components nootkatone (17%), alpha-terpineol (10%), linalool (10%) with ee (R)-(-)-linalool, limonene (0.8%) with ee (R)-(+)-limonene. These results confirm the interesting quality of Citrus EO from Brazil, ensuring their applications in many industries, products categories, including medical applications owing their physiological and psychopharmacological properties, which show similarities with Citrus EO from other countries.

Objective: The main objective of this study is to establish a training to restore the olfactory sensation after infection with SARS-CoV-2 virus and the sequel to the disease COVID-19, through the inhalation of a sequence of essential oils (EO), systematically. The secondary objective of this study aims at gathering in an organized way the publications on EO that have in the keywords, short running title, or objective the mucosa anti-inflammatory action, respiratory health action, immunological health action, mental and emotional health action, as well as EO that hinder the viral replication. The EO are lipophilic substances extracted from plant species; they are mainly constituted by terpenic structures that are therapeutic bioactives. Design: This best practice guide has made a brief compilation of previously published data into an easy-to-understand didactic table. Interventions: Based on the research compiled in the table, a sequence of EO for use by inhalation was organized. Results: According to the researchers mentioned in the review, the inhalation of EO resensitizes the neural pathways that allow the identification of aroma and flavor. Thus, when this pathway is damaged, the inhalation of EO can help to restore it in a few months, which the average time is 3 months, and can extend up to 8 months. Conclusions: Currently, the greatest demand for the restoration olfactory is due to the sequelae of disease COVID-19. However, EO can be used for a loss or decrease in smell or taste caused by other factors, such as psychotropic medications, chronic rhinitis and sinusitis, neurological pathologies, cancer treatments, postinfectious and posttraumatic olfactory loss, older people, and other causes.