title: FTIR-ATR spectroscopy applied to quality control of grape-derived spirits.
abstract: The Fourier transform infrared (FTIR) spectroscopic method with attenuated total reflectance (ATR) was used for predicting the alcoholic strength, the methanol, acetaldehyde and fusel alcohols content of grape-derived spirits. FTIR-ATR spectrum in the mid-IR region (4000-400 cm(-1)) was used for the quantitative estimation by applying partial least square (PLS) regression models and the results were correlated with those obtained from reference methods. In the developed method, a cross-validation with 50% of the samples was used for PLS analysis along with a validation test set with 50% of the remaining samples. Good correlation models with a great accuracy were obtained for methanol (r(2)=99.4; RPD=12.8), alcoholic strength (r(2)=97.2; RPD=6.0), acetaldehyde (r(2)=98.2; RPD=7.5) and fusel alcohols (r(2) from 97.4 to 94.1; RPD from 6.2 to 4.1). These results corroborate the hypothesis that FTIR-ATR is a useful technique for the quality control of grape-derived spirits, whose practical application may improve the efficiency and quickness of the current laboratory analysis.
authors.affiliation: Instituto Politécnico de Castelo Branco, Apartado 119, 6001-909 Castelo Branco, Portugal; Centro de Estudos Florestais, Instituto Superior de Agronomia, Universidade de Lisboa, 1349-017 Lisboa, Portugal. Electronic address: ofelia@ipcb.pt.
authors.forename: Ofélia
authors.initials: O
authors.lastname: Anjos
authors.affiliation: Centro de Estudos Florestais, Instituto Superior de Agronomia, Universidade de Lisboa, 1349-017 Lisboa, Portugal.
authors.forename: António J A
authors.initials: AJ
authors.lastname: Santos
authors.affiliation: CIMO - Mountain Research Center, Department of Biology and Biotechnology, Agricultural College of Bragança, Polytechnic Institut of Bragança, Campus Santa Apolónia, E 5301-855 Bragança, Portugal.
authors.forename: Letícia M
authors.initials: LM
authors.lastname: Estevinho
authors.affiliation: Instituto Nacional de Investigação Agrária e Veterinária-Unidade Estratégica de Investigação e Serviços de Tecnologia e Segurança Alimentar - Laboratório de Enologia - Unidade de Investigação de Viticultura e Enologia, Dois Portos, Quinta da Almoínha, 2565-191 Dois Portos, Portugal; ICAAM - Instituto de Ciências Agrárias e Ambientais Mediterrânicas, Universidade de Évora, Pólo da Mitra, Apartado 94, 7002-554 Évora, Portugal.
authors.forename: Ilda
authors.initials: I
authors.lastname: Caldeira
mesh_terms: D000079:Acetaldehyde / Q000032:analysis; D000434:Alcoholic Beverages / Q000032:analysis*; D000431:Ethanol / Q000032:analysis; D005638:Fruit / Q000737:chemistry*; D016018:Least-Squares Analysis; D000432:Methanol / Q000032:analysis; D011786:Quality Control; D015203:Reproducibility of Results; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*; D027843:Vitis; D014920:Wine / Q000032:analysis
chemical_list: D000431:Ethanol; D000079:Acetaldehyde; D000432:Methanol
keywords: Alcoholic strength; Attenuated total reflectance; Fourier transform infrared spectroscopy; Fusel alcohols; Grape-derived spirits; Methanol