Light-induced sensory and chemical changes in aquavit

Abstract

Aquavit in clear bottles was stored in sunlight, in fluorescent light and in the dark under conditions relevant for the retail trade. Every 2 wk over a 6 mo period, the odour and taste of the aquavit were characterized by descriptive sensory analysis and concentrations of volatile compounds were determined together with tristimulus colour analysis. Formation of geranium-leaf odour and taste were the most pronounced light-induced sensory changes. The colour of the samples stored in light was determined less green and yellow and the samples were bleached. Concentrations of many of the volatile compounds characteristic of aquavit, including carvone, decreased in light. Carvonecamphor and limonene photoproducts were formed by photochemical reactions of carvone and limonene, respectively. None of these photoproducts had geranium-leaf odour by gas chromatography-olfactometry, but a compound with low odour threshold had. The compound could not be detected by flame ionization. A photochemical reactor suitable for accelerated light storage of beverages was constructed. The sensory and chemical changes found after 8h irradiation in the reactor were similar to those taking place in aquavit stored for 4 mo in sunlight.