Food and Chemical Toxicology 124 (2019) 192–218 Contents lists available at ScienceDirect Food and Chemical Toxicology journal homepage: www.elsevier.com/locate/foodchemtox FEMA GRAS assessment of natural flavor complexes: Citrus-derived T flavoring ingredients Samuel M. Cohena, Gerhard Eisenbrandb, Shoji Fukushimac, Nigel J. Gooderhamd, F. Peter Guengeriche, Stephen S. Hechtf, Ivonne M.C.M. Rietjensg, Maria Bastakih, ∗ Jeanne M. Davidsenh, Christie L. Harmanh, Margaret McGowenh, Sean V. Taylori, a Havlik-Wall Professor of Oncology, Dept. of Pathology and Microbiology, University of Nebraska Medical Center, 983135 Nebraska Medical Center, Omaha, NE, 68198- 3135, USA b Food Chemistry & Toxicology, Kühler Grund 48/1, 69126 Heidelberg, Germany c Japan Bioassay Research Center, 2445 Hirasawa, Hadano, Kanagawa, 257-0015, Japan d Dept. of Surgery and Cancer, Imperial College London, Sir Alexander Fleming Building, London, SW7 2AZ, United Kingdom e Dept. of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, 37232-0146, USA f Masonic Cancer Center, Dept. of Laboratory Medicine and Pathology, University of Minnesota, Cancer and Cardiovascular Research Building, 2231 6th St. SE, Minneapolis, MN, 55455, USA g Division of Toxicology, Wageningen University, Stippeneng 4, 6708 WE, Wageningen, the Netherlands h Flavor and Extract Manufacturers Association, 1101 17th Street, NW Suite 700, Washington, DC, 20036, USA i Scientific Secretary to the FEMA Expert Panel, 1101 17th Street, NW Suite 700, Washington, DC,20036,USA ARTICLE INFO ABSTRACT Keywords: In 2015, the Expert Panel of the Flavor and Extract Manufacturers Association (FEMA) initiated a re-evaluation Citrus of the safety of over 250 natural flavor complexes (NFCs) used as flavoring ingredients. This publication isthe Natural flavor complex first in a series and summarizes the evaluation of54 Citrus-derived NFCs using the procedure outlined in Smith Botanical et al. (2005) and updated in Cohen et al. (2018) to evaluate the safety of naturally-occurring mixtures for their GRAS intended use as flavoring ingredients. The procedure relies on a complete chemical characterization ofeachNFC Safety evaluation intended for commerce and organization of each NFC's chemical constituents into well-defined congeneric groups. The safety of the NFC is evaluated using the well-established and conservative threshold of toxicological concern (TTC) concept in addition to data on absorption, metabolism and toxicology of members of the con- generic groups and the NFC under evaluation. As a result of the application of the procedure, 54 natural flavor complexes derived from botanicals of the Citrus genus were affirmed as generally recognized as safe (GRAS) under their conditions of intended use as flavoring ingredients based on an evaluation of each NFC andthe constituents and congeneric groups therein. Abbreviations: CF, Correction factor; CFR, Code of federal regulations; CHO, Chinese hamster ovary (cells); CYP, Cytochrome P450 (enzymes); DFG, Deutsche Forschungsgemeinschaft; DTC, Decision tree class; EFFA, European Flavour Association; EFSA, European Food Safety Authority; EMEA, European Medicines Agency; ERS/USDA, Economic Research Service/U.S. Department of Agriculture; FAO, Food and Agriculture Organization; FDA, Food and Drug Administration; FEMA, Flavor and Extract Manufacturers Association; FID, Flame ionization detector; GC, Gas chromatography; GC-MS, Gas chromatography-mass spectrometry; GEF, Global evaluation factor; GLP, Good laboratory practice; GRAS, Generally recognized as safe; IARC, International Agency for Research on Cancer; IFEAT, International Federation of Essential Oils and Aroma Trades; IOFI, International Organization of the Flavor Industry; JECFA, Joint FAO/WHO Expert Committee on Food Additives; JFFMA, Japan Fragrance and Flavor Materials Association; LC-MS, Liquid chromatography-mass spectrometry; LD50, Median lethal dose; MF, Mutant frequency; MLA, Mouse lymphoma assay; MoS, Margin of safety; MSD, Mass spectrometric detector; NAS, National Academy of Sciences; NFC, Natural flavoring complex; NOAEL, No observed adverse effect level; NTP, National Toxicology Program; OECD, Organization for Economic Co-Operation and Development; OSOM, Outerstripe of the outer medulla; PCI, Per capita intake; SCE, Sister chromatid exchange; SD, Sprague-Dawley (rat); SKLM, Senate Commission on Food Safety (Germany); TTC, Threshold of toxicological concern; UDS, Unscheduled DNA synthesis (assay); USDA, U.S. Department of Agriculture; US-EPA, U.S. Environmental Protection Agency; WHO, World Health Organization ∗ Corresponding author. E-mail address: [email protected] (S.V. Taylor). https://doi.org/10.1016/j.fct.2018.11.052 Received 17 April 2018; Received in revised form 19 November 2018; Accepted 23 November 2018 Available online 24 November 2018 0278-6915/ © 2018 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/BY-NC-ND/4.0/). S.M. Cohen et al. Food and Chemical Toxicology 124 (2019) 192–218 1. Introduction folding process. These materials are rich in monoterpenes, particularly d-limonene, a major constituent in Citrus essential oils. The collection of For over fifty years, the Expert Panel of the Flavor and Extract Citrus essential oils by distillation of Citrus peels and/or Citrus juices is Manufacturers Association (FEMA) has served as the primary, in- generally not practiced since distillation produces lower quality oils (Di dependent body evaluating the safety of flavoring ingredients for use in Giacomo and Di Giacomo, 2002). The exception is lime oil. Both dis- human food. The Expert Panel evaluates flavoring ingredients to de- tilled and cold-expressed lime oils are currently in commerce. The sharp termine if they can be considered “generally recognized as safe” (GRAS) flavor of distilled lime oil is desirable for some products and remainsan for their intended use as flavoring ingredients consistent with the 1958 important flavoring ingredient. Food Additive Amendment to the Federal Food Drug, and Cosmetic Act The remaining categories of Citrus flavoring materials are the pe- (Hallagan and Hall, 1995, 2009). Currently, the FEMA Expert Panel has titgrain/neroli oils and Citrus extracts. Petitgrain oils are prepared by determined that over 2700 flavoring ingredients have met the criteria steam distillation of the buds and/or leaves of the Citrus plant. Neroli oil for GRAS status under conditions of intended use as flavoring in- is prepared by the steam distillation of the flowers of C. aurantium. gredients. Finally, Citrus extracts are prepared from the fruit peel or the peel oil for A key part of the FEMA GRAS program is the cyclical re-evaluation use as flavoring ingredients. of the GRAS status of flavoring ingredients determined to be GRAS by the FEMA Expert Panel. Flavoring ingredients are generally divided into 2. History of food use two broad categories, chemically-defined flavoring materials and nat- ural flavor complexes (NFCs). The chemically defined flavoring mate- The Citrus genus includes a variety of fruits commonly found in rials are typically single chemical substances whereas the NFCs are markets for fresh consumption such as sweet oranges, lemons, grape- naturally occurring mixtures typically derived from botanical materials. fruits, tangerines, mandarins and limes. Juice products from sweet or- The Panel has previously completed two re-evaluations of the chemi- ange, lemon and grapefruit are high volume products in western con- cally defined flavoring ingredients and in 2015 expanded the re-eva- sumer markets. Other Citrus fruits, such as bergamot and bitter orange luation program to include more than 250 NFCs on the FEMA GRAS list are usually cultivated for their essential oils. In Japan, popular Citrus and other relevant NFCs using a scientifically-based procedure for the fruits include iyokan, hassaku, sikuwasya, natsumikan, mikan, yuzu, safety evaluation of NFCs (Cohen et al., 2018; Smith et al., 2005). The sudachi, kabosu and ponkan. procedure describes a step-wise evaluation of the chemical composition Despite the wide variety of Citrus fruits available today, genetic of an NFC. Since many NFCs are products of common plant biochemical analysis of Citrus trees indicate that all Citrus varieties known today pathways (Schwab et al., 2008), the constituents can be organized into originated from only a few types, the pummelo (C. maxima), the citron a limited number of well-established chemical groups referred to as (C. medica), the mandarin and the uncultivated papeda (C. papeda) congeneric groups. The safety of the intake of each congeneric group (Carbonell-Caballero et al., 2015; Velasco and Licciardello, 2014; Wu from consumption of the NFC is evaluated in the context of data on et al., 2014). All Citrus species are believed to have originated in absorption, metabolism, and toxicology of members of the congeneric southeast China and the Malaysian archipelago. East-west trade routes group. Groups of NFCs of similar chemical composition or taxonomy facilitated the introduction and eventual cultivation of Citrus into have been assembled to facilitate the re-evaluation of all the NFCs. The western territories (Calabrese, 2002). Archeological excavations in- first group re-evaluated comprises flavoring ingredients derived from dicate that citron trees were cultivated in Persia around ∼4000 BC. the Citrus genus and is the subject of the present report.