Development and validation of an assay method for phenolic flavor compounds in beer flavor standards

Analytical Session
Boris Gadzov, FlavorActiV Limited, Sanderum House, Oakley Road, Chinnor, Oxfordshire, OX39 4TW, United Kingdom
Co-author(s): Mark Powell, Quay Pharmaceuticals Limited, Deeside, UK; Dale Smith, FlavorActiV Limited, Chinnor, UK

ABSTRACT: Flavor standards are a well-established means of training professional sensory panels for the beer and beverage industries. The utilization of cyclodextrin encapsulated flavors provides a more representative and consistent sensory experience than raw flavor materials. Although sensory evaluation of the taste of flavor standards is an important aspect of quality control, using instrumental methods is equally important. Data from instrumental methods of analysis afford a more traceable and less subjective means of assuring quality and batch-to-batch consistency compared to sensory evaluation techniques. This study describes the development and validation of an assay method for seven phenolic flavor compounds (2-methylphenol, 4-ethylphenol, 2,6-dichlorophenol, 2-bromophenol, 2,4,6-trimethylphenol, methoxy-4-vinylphenol, and 2-isopropylphenol) complexed with cyclodextrin for encapsulation as beer flavor standards. An isocratic reversed-phase HPLC method was developed that was capable of separating all seven compounds, using a mobile phase comprising 47% aqueous phosphoric acid (0.1%) and 53% methanol at a flow rate of 0.5 mL min–1. The column was an ACE C18 (150 mm × 4 mm, 3 µm d.p., Advanced Chromatography Technologies) maintained at 35°C. Detection was performed by UV absorbance at either 225 or 261 nm, and the run time was 20 min. Adequate specificity was established for all seven flavor compounds. Over the range of application, correlation coefficient (R2) values were equal to or better than 0.9995, and y intercept values were close to zero. Recovery values for cyclodextrin-complexed samples ranged from 97.4 to 106.9%, and the poorest value for method precision was 3.2% RSD. The method’s performance is considered to be more than adequate to control these seven compounds at concentrations relevant to their use as flavor standards.

Boris Gadzov is director of taster management at FlavorActiV Limited in the United Kingdom. Boris provides professional sensory training to taste panels throughout the world for FlavorActiV and to many of the biggest brewers and beverage producers. Boris holds a Ph.D. degree in food molecular microbiology and holds a doctorate in veterinary medicine. A talented linguist, Boris is fluent in a number of languages, including Macedonian, Russian, Croatian, Bosnian, Serbian, Bulgarian, Polish, and German.