Thin‐layer chromatography–surface‐enhanced Raman spectroscopy and chemometric tools applied to Pilsner beer fingerprint analysis

Abstract

This work proposes a novel use of thin‐layer chromatography with detection by surface enhancement Raman spectroscopy (SERS) to generate chromatographic and spectral fingerprints of complex samples, aiming toward samples classification. Ten commercial beer brands were analyzed in order to verify clusters related to each brand and the brewery location. The samples were eluted in thin‐layer chromatography plates and sprayed by gold nanoparticles colloidal solution using a simple and cheap lab‐made apparatus. The plates were analyzed by SERS, so, at the end of the measurement, one SERS‐chromatogram matrix was acquired for each sample. The high sensitivity of the SERS analysis allows the detection of compounds in low concentrations, unseen via common thin‐layer chromatography detection procedures, increasing the information for fingerprint analyses. Because of the high complexity of the sample, coelution problems and slight shifts in chromatographic peaks might appear in this kind of analysis; it was necessary to use chemometric tools for data analysis. Two chemometric methods of data deconvolution were compared, multivariate curve resolution–alternating least squares and independent component analysis. From the chromatographic peaks recovered by both methods, it was possible to perform a fingerprint analysis using principal component analysis, which allowed identifying patterns among the samples according to the brands and brewery location of Pilsner beers produced in Brazil. Copyright © 2017 John Wiley & Sons, Ltd.

Insights into chemical and sensorial aspects to understand and manage beer aging using chemometrics

“…Within chemometric approaches, classification techniques aim to recognize patterns in data and sort observations into categories. Pattern recognition methods have been widely applied in beer science to discriminate among: geographical origin (Alcazar et al, 2012;Li et al, 2007;Tan et al, 2015), brand authenticity (Cajka et al, 2010;Di Egidio et al, 2011;Soares et al, 2017), beer style, and ingredients (Duarte et al, 2004;Giannetti, Mariani, Torrelli, & Marini, 2019;Perez-Rafols and Saurina, 2015). Furthermore, many classification methods have been used for discrimination between fresh and aged beer (Table 2).…”

“…Beer fingerprints can be defined as a group of molecules that together represent a specific state, condition, or type of beer, allowing for its discrimination (Medina, Pereira, Silva, Perestrelo, & Câmara, 2019). In beer science, many techniques can be employed to fingerprint a beer, such as nuclear magnetic resonance (NMR) (Rodrigues, Barros, Carvalho, Brandão, & Gil, 2011), near‐infrared spectroscopy (NIR) (Ghasemi‐Varnamkhasti & Forina, 2014), electric‐nose (e‐Nose) (Ghasemi‐Varnamkhasti et al., 2011), Raman spectroscopy (Soares, Ardila, & Carneiro, 2017), liquid chromatography‐mass spectroscopy (Mattarucchi et al., 2010), and gas chromatography coupled with mass spectrometry (GC‐MS) (Jiao et al., 2011; Rendall et al., 2015). Regardless of the approach, to be able to combine and extract useful inferences to understand beer aging from several data inputs and distinct variables, such as chemical and sensory data, there is a need to employ a set of statistical and mathematical tools known as “chemometrics” (Brereton et al., 2017).…”

Recent advances in linear and nonlinear Raman spectroscopy. Part XII

“…Soares, Ardila, and Carneiro used thin‐layer chromatography (TLC)‐SERS and chemometrics to carry out fingerprint analysis of the Pilsner beer. The high sensitivity of the SERS analysis allows the detection of compounds in low concentrations, unseen via common TLC detection procedures, increasing the information for fingerprint analyses . Soualmia et al studied aminomethyl coumarin as a potential SERS@Ag probe for the evaluation of protease activity and inhibition.…”

“…The high sensitivity of the SERS analysis allows the detection of compounds in low concentrations, unseen via common TLC detection procedures, increasing the information for fingerprint analyses. [42] Soualmia et al studied aminomethyl coumarin as a potential SERS@Ag probe for the evaluation of protease activity and inhibition. Band-Target Entropy Minimization (BTEM) analysis was successfully used to validate the present SERS approach.…”