Analytical Quantification of Phenolic Compounds in Barrel-Aged Alcoholic Beverages as a Control Measurement in the Manufacturing Process

Importance of the topic

Quantification of phenolic tannin compounds in barrel aged alcoholic beverages is vital for quality control and authentication of spirits such as whisky rum brandy and tequila These compounds influence color aroma taste and mouthfeel and serve as markers of genuine oak aging preventing adulteration and fraud

Objectives and overview of the study

• Establish HPLC and UHPLC methods to separate and quantify seven key tannin markers from oak aging
• Apply the methods to four beverage matrices whisky brandy rum and tequila
• Correlate aging time and total tannin concentration as an authenticity control measurement

Methodology and instrumentation

Sample preparation involved direct injection of a serially diluted standard mix and minimal treatment of commercial spirit samples

• Standards vanillic acid caffeic acid vanillin p coumaric acid syringaldehyde scopoletin synapaldehyde
• Instrumentation Agilent 1290 Infinity II LC with Flexible Pump Multisampler Multicolumn Thermostat and Diode Array Detector
• Columns HPLC ZORBAX Eclipse Plus C18 4.6×150 mm 3.5 μm UHPLC ZORBAX Eclipse Plus C18 3.0×50 mm 1.8 μm
• Mobile phases A 0.1 percent formic acid in water B methanol C acetonitrile
• HPLC gradient runtime about 40 minutes flow 1 mL per minute UHPLC gradient runtime about 9 minutes flow 0.85 mL per minute column temperature 35°C sample temperature 19°C detection at 290 nm

Main results and discussion

Both methods delivered excellent precision with retention time RSD below 0.3 percent in HPLC and below 0.16 percent in UHPLC and area RSD below 1.5 and 0.94 percent respectively Calibration curves showed linearity with R2 values above 0.998

UHPLC reduced analysis time by over 75 percent and cut solvent consumption by using a narrower column

Matrix quantification revealed aging trends

• Rum under ten years below 2 μg per mL rising to about 10 to 12 μg per mL at thirty years
• Brandy ten years about 1 μg per mL twenty years about 12 μg per mL
• Tequila reposado above 0.5 μg per mL añejo between 9 and 15 μg per mL depending on cask
• Blended whisky twelve years 5.3 μg per mL fifteen years 9.3 μg per mL eighteen years 10.6 μg per mL thirty years 12.6 μg per mL
• Single malt special editions nineteen and twenty one years aged in rum casks around 5.3 μg per mL indicating barrel origin effects

Benefits and practical applications of the method

The approach is robust rapid and solvent efficient It can be implemented as a routine quality control test to monitor oak aging authenticity detect adulteration and ensure sensory consistency of high value alcoholic beverages

Future trends and possibilities

Advances may include coupling with mass spectrometry for structural confirmation integration with two dimensional liquid chromatography expansion of the marker panel online process monitoring and multivariate data analysis to improve traceability and automation in production lines

Conclusion

Validated HPLC and UHPLC methods enable precise quantification of seven oak aging markers in multiple spirit matrices UHPLC offers substantial time and solvent savings A clear correlation between tannin content and aging time supports implementation as a control measurement for authentication and fraud prevention in the alcohol industry

Reference

• Fenemma OR Food Chemistry Acribia third edition 1130
• Praven K et al Journal of Pharmacognosy and Phytochemistry 2012 Vol 1 issue 3 2278-4136
• Wikipedia Tannin accessed December 2014
• Munoz Munoz A et al Journal of Chromatography A 2008 1213 218-223