title: A powerful methodological approach combining headspace solid phase microextraction, mass spectrometry and multivariate analysis for profiling the volatile metabolomic pattern of beer starting raw materials.
abstract: The volatile metabolomic patterns from different raw materials commonly used in beer production, namely barley, corn and hop-derived products - such as hop pellets, hop essential oil from Saaz variety and tetra-hydro isomerized hop extract (tetra hop), were established using a suitable analytical procedure based on dynamic headspace solid-phase microextraction (HS-SPME) followed by thermal desorption gas chromatography-quadrupole mass spectrometry detection (GC-qMS). Some SPME extraction parameters were optimized. The best results, in terms of maximum signal recorded and number of isolated metabolites, were obtained with a 50/30 μm DVB/CAR/PDMS coating fiber at 40 °C for 30 min. A set of 152 volatile metabolites comprising ketones (27), sesquiterpenes (26), monoterpenes (19), aliphatic esters (19), higher alcohols (15), aldehydes (11), furan compounds (11), aliphatic fatty acids (9), aliphatic hydrocarbons (8), sulphur compounds (5) and nitrogen compounds (2) were positively identified. Each raw material showed a specific volatile metabolomic profile. Monoterpenes in hop essential oil and corn, sesquiterpenes in hop pellets, ketones in tetra hop and aldehydes and sulphur compounds in barley were the predominant chemical families in the targeted beer raw materials. β-Myrcene was the most dominant volatile metabolite in hop essential oil, hop pellets and corn samples while, in barley, the predominant volatile metabolites were dimethyl sulphide and 3-methylbutanal and, in tetra hop, 6-methyl-2-pentanone and 4-methyl-2-pentanone. Principal component analysis (PCA) showed natural sample grouping among beer raw materials.
authors.affiliation: CQM - Centro de Química da Madeira, Universidade da Madeira, Centro de Ciências Exactas e da Engenharia da Universidade da Madeira, Campus Universitário da Penteada, 9000-390 Funchal, Portugal.
authors.forename: João L
authors.initials: JL
authors.lastname: Gonçalves
authors.affiliation: CQM - Centro de Química da Madeira, Universidade da Madeira, Centro de Ciências Exactas e da Engenharia da Universidade da Madeira, Campus Universitário da Penteada, 9000-390 Funchal, Portugal.
authors.forename: José A
authors.initials: JA
authors.lastname: Figueira
authors.affiliation: CQM - Centro de Química da Madeira, Universidade da Madeira, Centro de Ciências Exactas e da Engenharia da Universidade da Madeira, Campus Universitário da Penteada, 9000-390 Funchal, Portugal.
authors.forename: Fátima P
authors.initials: FP
authors.lastname: Rodrigues
authors.affiliation: ECM - Empresa de Cervejas da Madeira, PEZO, Parque Empresarial Zona Oeste, 9304-003 Câmara de Lobos, Funchal, Portugal.
authors.forename: Laura P
authors.initials: LP
authors.lastname: Ornelas
authors.affiliation: ECM - Empresa de Cervejas da Madeira, PEZO, Parque Empresarial Zona Oeste, 9304-003 Câmara de Lobos, Funchal, Portugal.
authors.forename: Ricardo N
authors.initials: RN
authors.lastname: Branco
authors.affiliation: CQM - Centro de Química da Madeira, Universidade da Madeira, Centro de Ciências Exactas e da Engenharia da Universidade da Madeira, Campus Universitário da Penteada, 9000-390 Funchal, Portugal.
authors.forename: Catarina L
authors.initials: CL
authors.lastname: Silva
authors.affiliation: CQM - Centro de Química da Madeira, Universidade da Madeira, Centro de Ciências Exactas e da Engenharia da Universidade da Madeira, Campus Universitário da Penteada, 9000-390 Funchal, Portugal. Electronic address: jsc@uma.pt.
authors.forename: José S
authors.initials: JS
authors.lastname: Câmara
mesh_terms: D001515:Beer / Q000032:analysis*; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D055432:Metabolomics / Q000379:methods*; D015999:Multivariate Analysis; D009930:Organic Chemicals; D052617:Solid Phase Microextraction / Q000379:methods*
chemical_list: D009930:Organic Chemicals
keywords: Beer; Global fingerprint; Multivariate statistical analysis; Raw materials; Solid phase microextraction (SPME); Volatile metabolites