81 Czech Journal of Food Sciences, 37, 2019 (2): 81–92 Food Analysis, Food Quality and Nutrition htps://doi.org/10.17221/202/2017-CJFS Chemical composition, antimicrobial and insecticidal activities of the tunisian Citrus aurantium essential oils Enis Ben Bnina 1 *, Hafedh Hajlaoui 2 , Ikbal Chaieb 3 , Majda Daami-Remadi 4 , Moncef Ben Said 5 , Hichem Ben Jannet 1 1 Department of Chemistry, Faculty of Sciences of Monastir, University of Monastir, Monastir, Tunisia 2 Laboratory of Environmental Microbiology, Faculty of Pharmacy, University of Monastir, Monastir, Tunisia 3 Regional Center of Research in Horticulture and Biological Agriculture of Chott-Mariem, University of Sousse, Chott-Mariem, Tunisia 4 Regional Center of Research on Horticulture and Organic Agriculture of Chott-Mariem, University of Sousse, Chott-Mariem, Tunisia 5 Laboratory of Parasitology and Mycology, Farhat Hached Hospital, Avenue Ibn El Jazzar Sousse, Tunisia *Corresponding author: benbninae@gmail.com Citation: Bnina E.B., Hajlaoui H., Chaieb I., Daami-Remadi M., Ben Said M., Ben Jannet H. (2019): Chemical composition, antimicrobial and insecticidal activities of the tunisian Citrus aurantium essential oils. Czech J. Food Sci., 37: 81–92. Abstract: Te chemical composition of volatile fractions from leaves, fowers and peels of Citrus aurantium growing in Tunisia obtained by hydrodistillation were analysed using GC and GC-MS. Furthermore, the isolated essential oils were evaluated for their in vitro antimicrobial activity against eight bacteria, eight phytopathogenic and nine human pathogenic fungi. Te essential oils from peels and its main compound limonene have been found to possess strong contact toxicity against four storage-grain insects. Te highest mortality rate was observed when the essential oil was applied against Cryptolestes ferrugineus, Liposcelis bostrychophila and Tribolium castaneum. Keywords: antimicrobial activity; Citrus aurantium; essential oil; insecticidal activity; limonene; volatile fractions Plants provide a multitude flavours and fragrances that found many applications in everyday life. Accord- ing to different authors, approximately 3000 plants species contain essential oils, among which only 300 are commercially important. Essential oils and some of their constituents are used not only in phar- maceutical products for their therapeutic activities, but also in agriculture, as food preserves and ad- ditives for human or animal use, in cosmetics and perfumes, and other industrial fields. In many cases, they serve as plant defence mechanisms against predation by microorganisms, insects, and herbi- vores (Bakkali et al. 2008). Complex composition of the essential oils and variety of chemical structures of their constituents are responsible for a wide range of biological activities, many of which are increasing interest in the fields of human and animal health. Particularly, many essential oils and their constitu- ents have been traditionally used for their biological activities, which were known since ancient times. Citrus aurantium (Rutaceae), commonly known as a bitter orange tree is an ever green tree of 2–2.5 m high, having white perfumed flowers and orange fruits, cultivated in tropical and subtropical zones. The Citrus genus marks its presence in daily life in the fields of traditional medicine, cosmetics, food