Confirmation of brand identity of a Trappist beer by mid-infrared spectroscopy coupled with multivariate data analysis

NOTICE: this is the author’s version of a work that was accepted for publication in TALANTA. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in TALANTA, 2011, volume 99. DOI:10.1016/j.talanta.2012.06.005peer-reviewedAuthentication of foods is of importance both to consumers and producers for e.g. confidence in label descriptions and brand protection respectively. The authentication of beers has received limited attention and in most cases only small data sets were analysed. In this study, Fourier-transform infrared attenuated total reflectance (FT-IR ATR) spectroscopy was applied to a set of 267 beers (53 different brands) to confirm claimed identity for samples of a single beer brand based on their spectral profiles. Skewness-adjusted robust principal component analysis (ROBPCA) was deployed to detect outliers in the data. Subsequently, extended canonical variates analysis (ECVA) was used to reduce the dimensionality of the data while simultaneously achieving maximum class separation. Finally, the reduced data were used as inputs to various linear and non-linear classifiers. Work focused on the specific identification of Rochefort 8º (a Trappist beer) and both direct and indirect (using an hierarchical approach) identification strategies were studied. For the classification problems Rochefort versus non-Rochefort, Rochefort 8º versus non-Rochefort 8º and Rochefort 8º versus Rochefort 6º and 10º, correct prediction abilities of 93.8%, 93.3% and 97.3% respectively were achieved.European Union (EU) 6th Framework Programme (TRACE project