Volatile biomarkers for wild mushrooms species discrimination Ricardo Malheiro a,b , Paula Guedes de Pinho c, ⁎, Sandra Soares c , António César da Silva Ferreira d,e , Paula Baptista a, ⁎⁎ a Mountain Research Centre (CIMO), School of Agriculture - Polytechnic Institute of Bragança, Campus St a Apolónia, Apartado 1172, 5301-855, Bragança, Portugal b REQUIMTE/Laboratory of Bromatology and Hydrology, Faculty of Pharmacy, Porto University, Rua Aníbal Cunha 164, 4050-047 Porto, Portugal c REQUIMTE/Laboratory of Toxicology, Faculty of Pharmacy, Porto University, Rua Aníbal Cunha 164, 4050-047 Porto, Portugal d CBQF - Centro de Biotecnologia e Química Fina – Laboratório Associado, Escola Superior de Biotecnologia, Universidade Católica Portuguesa/Porto, Rua Dr. António Bernardino Almeida, 4200-072 Porto, Portugal e Stellenbosch University, Private Bag X1, Matieland, 7602 Stellenbosch, South Africa abstract article info Article history: Received 3 April 2013 Accepted 6 June 2013 Available online 12 June 2013 Keywords: Wild mushrooms HS–SPME GC/IT–MS Volatiles Species discrimination Targeted and non-targeted analyses Principal component analysis Secondary metabolites present in the volatile fraction of six wild mushroom species (Clitocybe odora, Clitocybe fragrans, Hebeloma crustuliniforme, Lepista nuda, Tricholoma fracticum and Tricholoma terreum) were studied, as an attempt to identify compounds capable to distinguish mushroom species for taxonomic and authentication purposes. Volatiles were assessed by headspace solid phase microextraction (HS–SPME) and by gas chromatography/ion-trap mass-spectrometry (GC/IT–MS). By using target analysis, 46 volatiles were grouped in 5 chemical classes: alcohols, aldehydes, ketones, sesquiterpene-like compounds and ter- penes. Each species revealed a unique volatile profile, with changes in the dominant chemical class. Aliphatic compounds with eight carbon atoms, such as 3-octanol, 1-octanol and 3-octanone were the most abundant. The non-target approach application, using all HS–SPME–GC–MS data (raw chromatograms) aims to detect a large number of compounds to get a fingerprint of each sample. This procedure, involving previous data treatments as chromatogram data alignments, sample data fingerprints, and multivariate analysis, represents a powerful tool to execute an initial screening of the analytical results, enabling a faster interpretability of the results without time-consuming through identifications and quantifications. Unsupervised signal decomposition techniques such as principal component analysis (PCA) applied both to targeted and non-targeted approaches revealed 11 volatile compounds (3-octanol, 3-octanone, linalool, 1-octanol, 1-pentanol, (E)-2-octen-1-ol, hexanol, hexanal, (E)-2-octenal, ρ-anisaldehyde and sesquiterpene-like compound) in common with an important discriminating power, suggesting that those compounds can play a crucial biomarker role in the characterization of the six wild species of mushrooms. © 2013 Elsevier Ltd. All rights reserved. 1. Introduction In many countries around the world wild mushrooms are a very popular product being highly used, for thousands of years, as food product but also for medicinal and functional purposes (Beluhan & Ranogajec, 2011; Chang & Miles, 2004; Omarini, Henning, Ringuelet, Zygadlo, & Albertó, 2010). The unique and diversified flavors exhibited by several mushroom species are one of the characteristics accounting for their high popularity. In fact, some species are charac- terized for presenting specific pleasant flavors which are pointed to be the most important organoleptic characteristic of mushroom prod- ucts (Maga, 1981). Pleasant aromatic compounds include almond-, or anise-like odors, and floral or fruity odors (pineapple, lemon or orange, among others) (Jong & Birmingham, 1993). These distinctive flavors, obtained by sensory evaluation, are frequently used for mush- room species identification (Courtecuisse, 1999; Courtecuisse & Duhem, 2005). For instance, the flour flavor is typical of some species such as Calocybe gambosa, Entoloma lividum and Clitopilus prunulus; the anise flavor is common to Agaricus silvicola and Clitocybe odora (Breheret, Talou, Rapoir, & Bessiere, 1996); whereas the turnip, apri- cot and swamp gas or coal tar are characteristic flavors of some species of the genera Hebeloma, Cantharellus and Tricholoma, respec- tively (Courtecuisse & Duhem, 2005). Due to the great subjectivity of this process, a few attempts have been performed to assess the possibility of using the volatile fungal compounds, as secondary metabolites, on species identification and taxonomic classification. Larsen and Frisvad (1995) were the first to demonstrate the use of fungal volatile metabolites to discriminate be- tween many species of Penicillium. Although some studies focusing the identification of key com- pounds directly responsible for fruiting bodies flavor have been Food Research International 54 (2013) 186–194 ⁎ Corresponding author. Tel.: +351 222078935; fax: +351 222003977. ⁎⁎ Corresponding author. Tel.: +351 273303332; fax: +351 273325405. E-mail addresses: pguedes@ff.up.pt (P. Guedes de Pinho), pbaptista@ipb.pt (P. Baptista). 0963-9969/$ – see front matter © 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.foodres.2013.06.010 Contents lists available at SciVerse ScienceDirect Food Research International journal homepage: www.elsevier.com/locate/foodres