Light-induced sensory and chemical changes in aromatic bitters

Abstract

Every month for a year, samples of aromatic bitters stored in clear and green bottles under conditions relevant to the retail trade, (1) in sunlight, (2) in fluorescent light and (3) in the dark, were characterized by descriptive sensory analysis, tristimulus colorimetry and by the concentrations of 13 flavour compounds. Aromatic bitters stored in light developed a higher intensity of sweet and solvent-like odour, described by the assessors as catty-like or ribes. Bitters stored in light had a stronger tendency to become turbid and these samples had a fortified-wine-like flavour and were less bitter and less astringent. A new method in this context, growth curve analysis, was used successfully to detect significant time and treatment effects in the sensory data. By partial least-squares analysis only a minor part of the light-induced sensory effects in bitters could be accounted for by the concentration of flavour compounds.