Analytical Methods Analysis of human male armpit sweat after fenugreek ingestion: Characterisation of odour active compounds by gas chromatography coupled to mass spectrometry and olfactometry Riadh Mebazaa, Barbara Rega, Valérie Camel ⇑ AgroParisTech, UMR 1145 Ingénierie, Procédés, Aliments, F-75005 Paris, France INRA, UMR 1145 Ingénierie, Procédés, Aliments, F-75005 Paris, France article info Article history: Received 4 May 2010 Received in revised form 8 February 2011 Accepted 17 February 2011 Available online 20 February 2011 Keywords: Volatile compounds Odour compounds Fenugreek Pseudo-maple syrup urine disease Sweat Gas chromatography Direct-GC–olfactometry Solid-phase microextraction abstract In this study, the strong ‘‘maple-syrup’’ odour which appears after fenugreek ingestion was investigated. Headspace solid-phase microextraction (HS-SPME) was applied to extract volatile odourant compounds from human male armpit sweat samples. Two male volunteers were considered who have similar diet; they had to ingest fenugreek infusion over the same period of time. The HS-SPME extracts obtained were then analysed by gas chromatography coupled either to mass spectrometry (GC–MS) or flame ionisation detection and olfactometry (GC–O). In that latter case, a panel of eight assessors was used, and the detec- tion frequency methodology was applied. A total of 44 compounds could be identified in sweat samples, with a wide range of chemical structures, some of them being reported for the first time in human armpit sweat. Eight compounds appearing only after fenugreek ingestion could be identified: 2,5-dimethylpyr- azine, b-pinene, 3-octen-2-one, camphor, terpinen-4-ol, 4-isopropyl-benzaldehyde, neryl acetate and b-caryophyllene. Due to their odourant notes, such compounds should be responsible for the strong ‘‘maple-syrup’’ odour present in sweat after fenugreek ingestion. GC–O confirmed the role of some odou- rant compounds in the ‘‘maple-syrup’’ odour of sweat, especially 2,5-dimethylpyrazine which was the best perceived odour. Among these eight compounds, some of them were previously reported in the fenugreek seeds, namely b-pinene, 3-octen-2-one and camphor. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction Fenugreek (Trigonella foenum-graecum L.) is an annual herba- ceous plant widely cultivated in Mediterranean countries and Asia for years, and more recently in other countries such as Canada (Taylor et al., 1997). The yellowish seeds contain compounds with interesting proprieties which explain their use in various ways including medicine, nutrition, beverages, fragrances, cosmetics, smoking and for other industrial purposes (Djeridane et al., 2006). In fact, toasted and ground fenugreek seed is an essential ingredient of curry powders and is often mixed with breadstuffs (Blank, Lin, Devaud, Fumeaux, & Fay, 1997). Moreover, it is used as a seasoning in food products, and seed extracts are also used in imitation of vanilla, maple syrup and many other products (Altuntas, Özgöz, & Taser, 2005). Indeed, the seeds contain a wide range of odourant compounds, among them 3-hydroxy-4,5-di- methyl-2(5H)-furanone (sotolon) which is one of the most impor- tant high-value natural flavouring substances (Blank et al., 1997; Mazza, Di Tommaso, & Foti, 2002). Furthermore, the seeds contain steroidal saponins and 4-hydroxyisoleucine, which are known to have respectively hypocholesterolemic and hypoglycemiant activ- ity (Billaud & Adrian, 2001a; Billaud & Adrian, 2001b; Madar, Abel, Samish, & Arad, 1988; Pau, Petit, Sauvaire, & Ribes, 2003; Sauvaire, Ribes, Baccou, & Loubatieres-Mariani, 1991; Sharma et al., 1996; Taylor et al., 1997). However, despite its interesting proprieties, fenugreek use remains limited because, after ingestion, a bad odour appears, called ‘‘maple syrup’’, in human’s sweat and urine (Bartley, Hiltry, Andreson, Clairemont, & Maschke, 1981; Korman, Cohen, & Preminger, 2001). When used as supplement to cereals in cattle feeding it also gives an unpleasant taste to the meat and a long lasting typical smell to the milk (Mazza et al., 2002). This typical and strong odour is also observed in human milk and known to pass from the mother to her infant, as it was observed in the sweat and urine of newborn infants due to postnatal fenu- greek exposure via mother’s breast milk (Korman et al., 2001). In that case, this led to false diagnostics of ‘‘maple syrup urine dis- ease’’ (MSUD), also called ‘‘pseudo-MSUD’’, MSUD being an inborn error of amino acid metabolism (leading to neurological damage and mental retardation) which is revealed by the presence of ‘‘maple syrup ‘‘odour in the sweat and urine of newborn infants. 0308-8146/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.foodchem.2011.02.063 ⇑ Corresponding author at: AgroParisTech, UMR 1145 Ingénierie, Procédés, Aliments, F-75005 Paris, France. Tel.: +33 1 44 08 17 25; fax: +33 1 44 08 16 53. E-mail address: valerie.camel@agroparistech.fr (V. Camel). Food Chemistry 128 (2011) 227–235 Contents lists available at ScienceDirect Food Chemistry journal homepage: www.elsevier.com/locate/foodchem