Measuring Preservatives and Organic Acids in Wine and Spirits

The profile of organic acids present in a wine can be extremely informative, revealing key elements of the manufacturing process. It is also one of the most important parameters to determine wine authenticity.

In whiskey, brandy, cognac, or other spirits, the presence of some organic acids may indicate that maturation or distillation processes have been violated. Alternatively, their presence may indicate a proclivity to precipitate during storage.

Certain organic acids, such as ascorbic, benzoic, or sorbic acids, may be used as preservatives. The presence of these is subject to strict regulations. Even though sorbic acid may occur in certain alcoholic beverages naturally, its presence in others may suggest that the technological process has been severely violated or even completely falsified.

To help with the determination of important organic acids, Lumex Instruments provides a specially designed Organic Acids Chemical Kit_Wines. This is provided with a detailed analytical protocol, which enables the measurement of most critical organic acids in wines, spirits, and wine products – such as acetic, citric, tartaric, malic, succinic, and lactic acids.

This kit can also quantify certain other organic acids (such as oxalic, gluconic, and more), in addition to a range of preservatives including ascorbic, benzoic, and sorbic acids. The French Certification Committee, COFRAC, has certified the analytical method based on the protocol developed by Lumex Instruments.

Measurement Method

In the determination of organic acids, the capillary electrophoresis method is based on these acids’ differential migration and separation in fused silica capillary, driven by an electric field. Samples undergo simple dilution with water, and CE separation takes place in under 7 minutes.

Equipment and Reagent

For these measurements, the CAPEL-105M capillary electrophoresis system is used, while a personal computer that runs under the Windows® XP/7 operating system (with the dedicated software package ELFORUN also installed) is used for the acquisition of data, collection, processing, and output. All reagents used should be of analytical grade or better.

Example of a Real Analysis

. .
BGE: from Kit_Organic Acids_Wines
Capillary: Leff/Ltot=40/50 cm, ID=50 µm
Injection: 300 mbar*sec
Voltage: -15 kV
Temperature: +20 °C
Detection: 190 nm, direct

 

Sample

  • Young rose wine (upper trace)
  • Old red wine (low trace)

Found

1 – succinic acid (0.47 g/L; 0.66 g/L)
2 – malic acid (2.2 g/L; n.d.)
3 – tartaric acid (2.1 g/L; 1.9 g/L)
4 – citric acid (0.19 g/L; n.d.)
5 – acetic acid (0.33 g/L; 1.4 g/L)
6 – lactic acid (n.d.; 1.6 g/L)
7 – sorbic acid (n.d.; 0.85 mg/L)

This information has been sourced, reviewed and adapted from materials provided by Lumex Instruments.

For more information on this source, please visit Lumex Instruments.

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