NMR spectroscopy in wine authentication: An official control perspective

Abstract

Wine authentication is vital in identifying malpractice and fraud, and various physical and chemical analytical techniques have been employed for this purpose. Besides wet chemistry, these include chromatography, isotopic ratio mass spectrometry, optical spectroscopy, and nuclear magnetic resonance (NMR) spectroscopy, which have been applied in recent years in combination with chemometric approaches. For many years, 2H NMR spectroscopy was the method of choice and achieved official recognition in the detection of sugar addition to grape products. Recently, 1H NMR spectroscopy, a simpler and faster method (in terms of sample preparation), has gathered more and more attention in wine analysis, even if it still lacks official recognition. This technique makes targeted quantitative determination of wine ingredients and nontargeted detection of the metabolomic fingerprint of a wine sample possible. This review summarizes the possibilities and limitations of 1H NMR spectroscopy in analytical wine authentication, by reviewing its applications as reported in the literature. Examples of commercial and open‐source solutions combining NMR spectroscopy and chemometrics are also examined herein, together with its opportunities of becoming an official method.

A Review of Wine Authentication Using Spectroscopic Approaches in Combination with Chemometrics

“…Initially, site-specific natural isotopic fractionation NMR (SNIF-NMR) spectroscopy was proposed as a tool for detecting the biochemical origin of ethanol according to the natural distribution of deuterium [49], which can reveal the unauthorised use of chaptalisation (sugar addition) in winemaking, for example [50]. NMR spectroscopy can be applied for qualitative analysis to determine molecular structures and for compositional profiling of a sample [51], as well as for quantitative analysis of analytes such as amino acids, alcohols, sugars, carboxylic acids and their derivatives, and phenolic compounds [50]. NMR can be based on acquisition of 1 H, 2 H, or 13 C spectra; for wine authentication, 1 H NMR spectroscopy is most advantageous as data acquisition is fast and highly reproducible compared to other techniques [33].…”

“…NMR can be based on acquisition of 1 H, 2 H, or 13 C spectra; for wine authentication, 1 H NMR spectroscopy is most advantageous as data acquisition is fast and highly reproducible compared to other techniques [33]. Moreover, NMR with advancements such as automation of analysis has been introduced commercially and adapted to wine authentication (e.g., Bruker's WineScreener TM ) [50]. Using the possibilities of NMR spectroscopy, different aspects of wine authenticity have been addressed (Table 5).…”

“…Among the most mature forms of spectroscopy for food and beverage classification, NMR has been applied to wine authentication for decades. Initially, site-specific natural isotopic fractionation NMR (SNIF-NMR) spectroscopy was proposed as a tool for detecting the biochemical origin of ethanol according to the natural distribution of deuterium [ 49 ], which can reveal the unauthorised use of chaptalisation (sugar addition) in winemaking, for example [ 50 ]. NMR spectroscopy can be applied for qualitative analysis to determine molecular structures and for compositional profiling of a sample [ 51 ], as well as for quantitative analysis of analytes such as amino acids, alcohols, sugars, carboxylic acids and their derivatives, and phenolic compounds [ 50 ].…”

Nuclear Magnetic Resonance Metabolomics with Double Pulsed-Field-Gradient Echo and Automatized Solvent Suppression Spectroscopy for Multivariate Data Matrix Applied in Novel Wine and Juice Discriminant Analysis

“…It has identified possible counterfeit products by monitoring the presence of specific metabolites within a sample [ 2 ]. This technique has also identified possible adulterations in coffee [ 3 , 4 ], tea bags for herbal infusions [ 5 , 6 , 7 , 8 ], vodka [ 9 , 10 ], milk and dairy products [ 11 , 12 , 13 ], honey [ 9 , 14 , 15 ], beer [ 9 , 16 ], oil [ 7 , 17 , 18 ], wine [ 2 , 19 , 20 , 21 , 22 ], juice [ 2 , 23 , 24 ]; vinegar [ 2 , 9 , 25 ], tequila [ 9 , 25 , 26 ], rum [ 9 ], and whiskey [ 9 ], amongst others. Spectroscopic and spectrometric techniques combined, in some cases, with chromatographic methods are useful to assure the food quality to avoid adulterations and fraud and determine the geographical origin of the constituent ingredients, because consumers consider this data as one of the principal quality indicators [ 27 ].…”

“…Despite the restricted Limits of Quantification (LOQ) and Detection (LOD), 1 H-NMR has been a useful method for the geographical origin authentication of several food matrices, with clear advantages of being nondestructive, fast, reproducible, and reliable, compared to chromatography coupled with MS techniques [ 19 , 20 , 29 , 30 , 31 ]. The combination of high-reproducible, noninvasive, rapid, and simple-use proton Nuclear Magnetic Resonance Spectroscopy ( 1 H-NMR) with Multivariate Statistical Analysis (MSA) for foodstuff metabolomics has emerged over the last decades for the implementation of models to trace the food quality, origin, manufacture, or authenticity [ 32 ].…”