Effect of light on sparkling wines: sensory and chromatographic evaluation of different elaboration methods and maturation states

Sensory evaluation studies of light-struck flavour reported in the literature mostly concentrate on the onset of typical off-aromas related to sulfur-containing products However, some recent chromatographic studies have also confirmed the change in varietal aroma compounds during light exposure before attaining the sensory threshold for wine faults. In this study, we have looked for aroma changes by sensory evaluation prior to the onset of typical light-struck notes in sparkling wines of different composition, technology and duration of lees contact. Evaluations were done in two different settings: i) completely randomised blind tasting, and ii) a tasting of a series of samples of known identity without the knowledge of the randomised order of light exposure durations. Thus, we aimed to simulate the real-life experience of consumers who do not have information about the actual shelf life of sparkling wines they buy. The main results are that, after moderate light doses – prior to the onset of light-struck off-flavours – tasters cannot distinguish significant differences depending on the length of exposure. In some cases, they rated moderately illuminated samples even higher than the control, reporting pleasant mellow, honey-like notes. HS–SPME–GC–MS studies supported a non-monotonic change in the aroma profile, similarly to a few recent findings reported in the literature. We also found marked differences in these temporal evolution patterns depending on the composition, technology, and vintage of the sparkling wine samples. We conclude that a proper consumer protection protocol would entail the monitoring of the light exposure of the bottles and consequently not selling wines when the critical light dose has been absorbed, which ultimately triggers a perceptible light-struck flavour.