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In Vino Veritas? – How Amino Acid Analysis Can Reveal Wine Adulteration

Team TFS
Team TFS


Wine consumption increased globally over the past years but interestingly, the global wine market dipped during the COVID-19 pandemic in 2020, despite an increase in offsite consumption, mainly due to many countries being on lockdown, restaurant closures, and the cancellation of events.

With the pandemic being a somewhat time-limited phenomenon, the worldwide wine market is expected to recover and projected to grow from $364.25 billion in 2019 to $444.93 billion by 2027 at a compound annual growth rate (CAGR) of approx. 6%.

The market growth is reported to be predominantly driven by:

  • Emergence of e-commerce shopping

  • Increasing alcohol socialization among consumers

  • Trend for wine premiumization

Increasing demand for a premium product not only requires proof the quality really meets the price point but opens the door for food fraud. As a result, the number of adulterated wines on the market may increase and the quality can be compromised.

While wine connoisseurs claim they’ll detect any affected organoleptic properties by tasting, sniffing, or by watching the wine in the glass, the average wine lover (as well as winemakers) may want to rely on a more objective approach.

There are many ways to check what’s in your wine glass and identify top wine spoilers. A recently published application note explores a simple, yet reliable and robust method addressing the question about the premium status of wine by analyzing amino acids with HPLC and mass detection.

How Amino Acid Content Affects Wine Aroma

Various reports show the correlation between the amino acid composition in vine and grape varieties, geographical origin, vintage year, and other features. While the amino acid content in the grape must is influenced by the growing techniques, terroir, and the grape variety, the wine produced is primarily determined by the selection of yeast strains and treatments used during fermentation.

Amino acids in the grape must serve as a nitrogen source and precursor for the formation of aromas by yeast, which is specialized for aroma development. The resulting wines show a characteristic amino acid pattern. Analysis of the amino acids in wine is used to detect these characteristic patterns in both the must and the finished vine, not only for quality control as well as to identify product adulterations, but also to differentiate products and verify advertised features.

With society’s growing demand for high-quality whites, reds, and rosés comes an increased need for a simple, yet accurate analysis of amino acids during manufacturing, fermentation, and aging of wine.

Challenges in Amino Acid Analysis with HPLC-UV

The traditional HPLC-UV method checks most of the boxes for a simple, reliable, and reproducible analysis. But, when looking at amino acids, there are a couple of points consider.

Most amino acids lack strong chromophores and as a result, the absorption of UV-Vis light is poor, except for aromatic amino acids (tryptophan, phenylalanine, and tyrosine) which absorb well at 280 nm. HPLC-UV detection is therefore not ideal for accurate detection and quantification of amino acids. Additionally, there are challenges with the retention of hydrophilic amino acids on reverse-phase (RP) columns.

To solve these problems, HPLC-UV methods involve pre- or post-column derivatization of the amino acids. While derivatization increases the sensitivity and boosts the separation efficiency of polar amino acids, these protocols have limits and require additional steps in sample preparation. Any additional manual step affects the robustness and reproducibility of the method due to the risk of errors.

Besides, many derivatization reagents are toxic and may complicate the sample matrix, which can result in interfering peaks in the target chromatogram.

With these disadvantages, is there a better solution to accurately analyze amino acid content in wine?

Yes! The answer is hydrophilic interaction liquid chromatography (HILIC), which allows for underivatized analysis of the amino acid profiles.

Benefits of Using HILIC-MS to Analyze Amino Acid Patterns

To combat the limitations of HPLC-UV analysis methods, winemakers and brewers can now turn to a simplified and more eco-friendly method: HILIC coupled with mass detection.

The use of HILIC-MS methods for analyzing amino acid patterns in grape must and wine are beneficial because:

  • Elimination of the need for derivatization of AA in a sample before analysis, which reduces systematic and random errors in sample preparation, and saves time

  • Reduction of the complexity of the sample matrix

  • Minimized exposure to toxic derivatization reagents

  • Coupling this method with MS gives accurate quantification when full separation is not possible due to the complex sample mixture.

HILIC-MS Methods Ensure Quality Control in Wine Production

To consistently produce top-shelf wines year-after-year you must have quality control over not only the grapes and grape must, but also tight control of the fermentation and aging process. This type of control always begins with a simple, reliable, reproducible, and robust analytical test method like HILIC-MS.

This improved method will help winemakers meet the increasing demand for premium wines and keep wine adulteration and potential food fraud at bay, which is great news for all wine lovers out there!

Do you want to learn more about wine testing? Check out our dedicated wine testing webpage for tips and tricks.
1 Comment
Involved Contributor II
Involved Contributor II

Very nice article @melanie-helmle . (I´d like to see this done in an Orbitrap also!)