title: Citrus essential oils and their influence on the anaerobic digestion process: an overview.
abstract: Citrus waste accounts for more than half of the whole fruit when processed for juice extraction. Among valorisation possibilities, anaerobic digestion for methane generation appears to be the most technically feasible and environmentally friendly alternative. However, citrus essential oils can inhibit this biological process. In this paper, the characteristics of citrus essential oils, as well as the mechanisms of their antimicrobial effects and potential adaptation mechanisms are reviewed. Previous studies of anaerobic digestion of citrus waste under different conditions are presented; however, some controversy exists regarding the limiting dosage of limonene for a stable process (24-192 mg of citrus essential oil per liter of digester and day). Successful strategies to avoid process inhibition by citrus essential oils are based either on recovery or removal of the limonene, by extraction or fungal pre-treatment respectively.
authors.affiliation: AINIA Technology Centre, Parque Tecnológico Valencia, Benjamin Franklin 5-11, E-46980 Paterna, Valencia, Spain. Electronic address: bruiz@ainia.es.
authors.forename: B
authors.initials: B
authors.lastname: Ruiz
authors.affiliation: GIRO Joint Research Unit IRTA-UPC, Department of Agrifood Engineering and Biotechnology, Universitat Politècnica de Catalunya - BarcelonaTECH, Parc Mediterrani de la Tecnología, Building D4, E-08860 Castelldefels, Barcelona, Spain. Electronic address: xavier.flotats@upc.edu.
authors.forename: X
authors.initials: X
authors.lastname: Flotats
mesh_terms: D000693:Anaerobiosis; D056804:Biofuels / Q000032:analysis; D002957:Citrus / Q000737:chemistry*; D053138:Cyclohexenes / Q000032:analysis / Q000494:pharmacology*; D005658:Fungi / Q000187:drug effects*; D005659:Fungicides, Industrial / Q000032:analysis / Q000494:pharmacology*; D000077222:Limonene; D008697:Methane / Q000378:metabolism; D009822:Oils, Volatile / Q000032:analysis / Q000494:pharmacology*; D013729:Terpenes / Q000032:analysis / Q000494:pharmacology*; D018505:Waste Management / Q000379:methods*
chemical_list: D056804:Biofuels; D053138:Cyclohexenes; D005659:Fungicides, Industrial; D009822:Oils, Volatile; D013729:Terpenes; D000077222:Limonene; D008697:Methane
keywords: Anaerobic digestion; Citrus essential oils; Citrus waste; Limonene; Orange waste