Chemical and sensory effects of storing sauvignon Blanc wine in colored bottles under artificial light

Impact of light on protective fractions of Cu in white wine: Influence of oxygen and bottle colour

Cu(II)-organic acid (fraction I) and Cu(I)-thiol (fraction II) complexes can suppress sulfhydryl off-aromas in wine. This study investigated the impact of light exposure on the protective fractions of Cu of bottled white wine. Fluorescent light-exposed Chardonnay with two initial concentrations of dissolved oxygen (0.5 and 10 mg/L) was stored in different coloured bottles and concentrations of Cu fractions and riboflavin, a photo-initiator at 370-440 nm, were measured during 110 days storage. Light-exposed wines with lower oxygen concentrations resulted in a 100-fold decrease in the Cu fraction I half-life, and a 60-fold decrease for Cu fractions I and II combined. The half-life for Cu fraction I decay during light exposure was extended 30-fold with the use of brown compared to flint glass. Light exposure can rapidly exhaust the protective Cu fractions in wine, and bottles with less light transmission below 440 nm can slow this loss.

Effect of storing conditions (lighting, temperature and bottle color) on rosé wine attributes

The majority of rosé wines are bottled in clear bottles as color is an important factor in consumer preference. Post-bottling wine can be exposed to UV-visible light and temperature fluctuations resulting in quality degradation. This study investigated the impact of bottle color (flint and antique green), light exposure (darkness, LED and fluorescent bulb), and temperature (12 °C and 22 °C) on rosé wine quality using a full factorial design with three different wines (Grenache, Pinot noir and Zinfandel). The impact on chemical composition, color, phenolics and aromatics was determined. Projective mapping was carried out for sensorial analysis. Changes in the aromatics, color and phenolic composition were detectable after three months and more noticeable after six months of storage. Overall, all variables studied impacted rosé wine characteristics significantly. However, higher temperature in combination with clear glass bottles under fluorescent light were the most detrimental conditions.

Flint glass bottles cause white wine aroma identity degradation

Due to marketing recommendations, white wines are often bottled in flint glass to improve aesthetics and showcase wine color. Although this practice is known to cause a wine fault, the influence of light on the fruity and flowery aromatic profile of wine is unknown. The aim of this study was to investigate the changes to the white wine volatilome under typical supermarket shelf conditions, using 1,052 bottles of 24 white wines. After only 7 d of shelf life in flint glass bottles, a dramatic loss in terpenes (10 to 30%) and norisoprenoids (30 to 70%) was recorded, whereas colored glass bottles did not evidence such behavior even after 50 d, and darkness preserved the wine's fruity and flowery aromatic integrity. We also proposed an alternative mechanism for the insurgence of the lightstrike off-odor, which takes the varietal aroma loss into account. In light of this understanding of the flint glass negative impact on white wine aroma identity and sensorial character, this packaging should be strongly discouraged. The same findings should be valid for a wide range of several daily consumed foodstuff where transparent packaging is used.

Combined effects of sulfur dioxide, glutathione and light exposure on the conservation of bottled Sauvignon blanc

Oxygen exposure may trigger a series of changes that could be detrimental to the quality white wines. This study evaluated the combined effects of sulfur dioxide, glutathione and light exposure on the chemistry and sensory perception of bottled Sauvignon blanc. The wines were manually bottled into clear bottles, closed with low oxygen transfer rate stoppers, and stored for three months, either exposed or protected from light. The wines exposed to artificial light showed higher rates of sulfite loss and oxygen consumption, were significantly darker in color, exhibited significant changes in the concentration of phenolics and volatile compounds, were perceived as less fruity/floral, and had higher nuances of solvent, earthy and honey aromas than the ones protected from light. The treatments with higher amounts of initial sulfites and glutathione were able to delay some of these changes but were less significant than protecting the wines from artificial light.

Effects of light exposure on chemical and sensory properties of storing Meili Rosé wine in colored bottles

The changes of chemical compositions and sensory characteristics of Meili rosé wine in flint, antique green and amber bottles were studied under continuous illumination for 160 days in two light sources (white fluorescent light, UV light). The results showed that light exposure caused significant changes in free sulfur dioxide content, Fe(III):Fe(II) ratio and Malvidin-3-O-glucoside content, responsible for the accelerated color evolution of Meili rosé wine during bottle storage. Some notable aroma-related changes were also observed for sensory characteristics, particularly for wines in flint bottles, boiled-like odor and oxidized odor appeared. Bottle color played a key role in preventing rosé wine from light exposure, following the order: amber bottle > green bottle > flint bottle. Besides UV light, white fluorescent light did have negative effects on rosé wine quality, considering its ubiquitous presence and long-term exposure in practice. The underlying mechanisms related to photochemical reactions in wine were further discussed.

Investigating the Role of Antioxidant Compounds in Riboflavin-Mediated Photo-Oxidation of Methionine: A 1H-NMR Approach

Riboflavin (RF) is a well-known photosensitizer, responsible for the light-induced oxidation of methionine (Met) leading to the spoilage of wine. An NMR approach was used to investigate the role of gallic acid (GA) and sulfur dioxide (SO₂) in the RF-mediated photo-oxidation of Met. Water solutions of RF and Met, with and without GA or SO₂, were exposed to visible light for increasing time in both air and nitrogen atmospheres. Upon light exposure, a new signal appeared at 2.64 ppm that was assigned to the S(O)CH₃ moiety of methionine sulfoxide. Its formation rate was lower in a nitrogen atmosphere and even lower in the presence of GA, supporting the ability of this compound in quenching the singlet oxygen. In contrast, SO₂ caused relevant oxidation of Met, moderately observed even in the dark, making Met less available in donating electrons to RF. The competition of GA versus Met photo-oxidation was revealed, indicating effectiveness of this antioxidant against the light-dependent spoilage of wine. A pro-oxidant effect of SO₂ toward Met was found as a possible consequence of radical pathways involving oxygen.