What is it about?

Glass bottles played a key role in the wine industry and helped us to decrease or eliminate faults, increase quality and deliver wine to the consumers with recognizable aroma identity. That is why the wines in glass bottles became so popular. Traditionally, the color of the wine bottle was green or amber. However, lately, there are commercial demands on the wine industry to use lighter/thinner and flint glass bottles. According to the marketing rules: “the consumers want to see the wine that they are purchasing because they are better able to assess the color and determine if the food is of good quality.” A flint bottle seems to still be acceptable for a highly perishable product, such as a whole milk with a shelf life of 4-6 days. But what happens when a non-perishable beverage, such as a wine, is distributed in clear flint glass? For the scientists it is undoubted that light exposure can damage the quality of foodstuffs, shorten their lifetime, harm their nutritional value, and cause serious and irreversible sensorial problems. Already in the 70s, it has been proven that the lightstrike off-odor in wine is caused by chemical reactions induced by the light that passes through bottle glass. The work just published to PNAS demonstrated that several important wine aroma compounds, so far considered stable, are quickly degraded already after one or two weeks of shelf life in flint glass bottles. Dozens of volatile compounds, those bearing one or more double bonds in their chemical structure, are prone to photodegradation. Including several terpenes and norisoprenoids, key molecules modulating the flowery and fruity aroma of white wines. Therefore, losing such important aroma compounds, wine loses its identity and its ability to mask wine faults.

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Why is it important?

Winemakers do their best to deliver wines of high quality and recognizable identity. Till now they believed that temperature and oxygen are the main enemies of wine quality during its shelf life, but this study provided scientific evidence that the biggest wine quality enemy is light, when the bottle does not provide any protection. The discovery that light damages wine composition in such a dramatic way, will have a great impact on foodstuff, packaging and marketing research and production.

Perspectives

If the consumers and oenophiles want to fully appreciate the diversity of each wine, enjoying those pleasant and subtle sensory properties associated with the cultivar and terroir, they should consider purchasing wine bottled in colored glass (the darker the better). If national and international wine organizations want to protect wine denominations of origin, preserving the wine’s integrity, they should advise their members to avoid flint glass bottles.

Panagiotis Arapitsas
West Attica University

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This page is a summary of: Flint glass bottles cause white wine aroma identity degradation, Proceedings of the National Academy of Sciences, July 2022, Proceedings of the National Academy of Sciences,
DOI: 10.1073/pnas.2121940119.
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