The maple syrup odour of the “candy cap” mushroom, Lactarius fragilis var. rubidus
Graphical abstract
Highlights
► Fresh candy cap mushrooms are odourless, but have an intense maple syrup odour when dried. ► An SPME GC–MS headspace analysis identified 3-amino-4,5-dimethyl-2(5H)-furanone. ► 3-Amino-4,5-dimethyl-2(5H)-furanone is likely the source of the odour from dried candy cap mushrooms.
Section snippets
Subject and source
The candy cap mushrooms, Lactarius fragilis var. rubidus Hesler & A. H. Smith [synonym Lactarius rubidus (Hesler & Smith) Methven nom. prov.] were collected in Humboldt County, California and identified by DAD. When it is cooked or dried, this mushroom has an intense and persistent fragrance. The odour has generally been described as aromatic (Hesler and Smith, 1979) and more specifically as the odour of maple syrup, butterscotch, fenugreek, or burnt sugar (Arora, 1986; Bessette et al., 2009).
Previous work
12-Hydroxycaryophyllene-4,5-oxide has been identified from L. camphoratus (Daniewski et al., 1981). 3-Amino-4,5-dimethyl-2(5H)-furanone (quabalactone III, 1) has been identified as a component from Lactarius helvus (Fries) Fries, a European mushroom with a fenugreek odour (Rapior et al., 2000). Quabalactone III was originally identified in the flowers of the Mexican tree Quararibea funebris (Raffauf et al., 1984; Zennie and Cassady, 1990).
Present study
Headspace volatiles from dried sporocarps of L. fragilis var. rubidus were analysed using a Supelco solid phase microextraction (SPME) apparatus, equipped with a 100 μm polydimethylsiloxane fibre. Gas chromatography–mass spectrometry (GC–MS) showed quabalactone III, was a major compound in the headspace volatiles from this mushroom. This compound was tentatively identified by comparison of published mass spectra in the NIST 1998 computerised mass spectral library, and confirmed by comparison of
Chemotaxonomic significance
Mushrooms have a wide variety of odours, which are key characters in the identification of some species (Chiron and Michelot, 2005). The maple syrup odour is used to distinguish L. fragilis var. rubidus from other Lactarius species (Methven, 1997). There are several compounds that have maple syrup-like odours (Fig. 2). 2-Hydroxy-3-methyl-2-cyclopenten-1-one (cyclotene or maple lactone, 3) is a pronounced odourant in natural maple syrup (Alli et al., 1992; Filipic et al., 1965; Kallio, 1988).
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Cited by (4)
Odor-contributing volatile compounds of wild edible Nordic mushrooms analyzed with HS–SPME–GC–MS and HS–SPME–GC–O/FID
2019, Food ChemistryCitation Excerpt :Similarly, de Pinho and others reported farm-feed, floral, honey-like, nutty and hay-herb type odors in 11 Portuguese wild mushrooms (de Pinho et al., 2008). After the classic experiments on mushroom volatiles (Cronin & Ward, 1971; Picardi & Issenberg, 1973; Pyysalo, 1976; Pyysalo & Suihko, 1976; Thomas, 1973), there has been a recent rise in research activity related to the volatile compounds in both cultivated and wild edible mushrooms (Aprea et al., 2015; Cho, Kim, Choi, & Kim, 2006; Cho et al., 2007; Csóka, Geosel, Amtmann, & Korany, 2017; de Pinho et al., 2008; Fons, Rapior, Eyssartier, & Bessière, 2003; Grosshauser & Schieberle, 2013; Kleofas et al., 2015; Misharina, Muhutdinova, Zharikova, Terenina, & Krikunova, 2009; Politowicz, Lech, Sánchez-Rodríguez, Szumny, & Carbonell-Barrachina, 2017; Rapior, Marion, Pélissier, & Bessière, 1997; Tietel & Masaphy, 2018; Wood et al., 2012; Wood, Brandes, Watson, Jones, & Largent, 1994; Zhang et al., 2018; Zhou, Feng, & Ye, 2015). These publications demonstrate that each mushroom species has a distinct volatile compound profile.
The Chemistry of Mushrooms: A Survey of Novel Extraction Techniques Targeted to Chromatographic and Spectroscopic Screening
2016, Studies in Natural Products ChemistryCitation Excerpt :Even in the case of mushrooms analysis, several publications have reported the use of SPME for sample preparation. In this review, only the most relevant papers of the last decade have been summarized in Table 9.1 [38–70]. This sampling methodology is again based on the use of a small sorbent surface, as in SPME, which is coated, in this case, onto a magnetic stirrer encapsulated in glass.