Sur Lie, meaning "on the lees."
Perhaps because various wineries release products labeled "Koshu Sur Lie," it is a term widely recognized even among Japanese wine fans.
However, many people might only have a vague understanding of what Sur Lie actually is.
Here, let us take another look and think about Sur Lie.
What is Sur Lie?
Sur Lie is a winemaking technique where wine is kept on its lees after fermentation finishes to impart umami, flavor, and other qualities through the autolysis of yeast.
Normally, white winemaking involves racking off the lees immediately after fermentation, but the Sur Lie method means it is a winemaking method where that "racking" is not performed...
As mentioned at the beginning, while the term Sur Lie itself may be familiar to Japanese wine fans, it is not a method unique to Japanese wine.
Sur Lie is a winemaking technique adopted around the world, and the Loire region in France is particularly famous for it.
For now, let us keep this in mind as basic knowledge.
The Loire and Sur Lie
As mentioned earlier, the Loire region is famous for Sur Lie.
However, Sur Lie is only permitted for "Muscadet" and "Gros Plant" in the Pays Nantais area downriver along the Loire.
Since it does not seem to be adopted throughout the entire Loire region, please note that not all white wines from across the Loire region are made with Sur Lie.
Now, let us explain the general winemaking process of Sur Lie (in the case of Muscadet).
Stirring & Débourbage
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Fermentation at 18–20°C
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Cold stabilization (tartrate removal) without malolactic fermentation
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No racking until bottling the following spring (Sur Lie)
In Japan, Sur Lie is mainly used for Koshu wines, and although there are slight variations, they are believed to be bottled and shipped following almost the same general flow.
Sur Lie imparts umami and flavor to wine.
Like Koshu, Muscadet is an elegant grape variety with a mild personality, which may be why Sur Lie has been traditionally adopted.
*Though not always publicized, Sur Lie is also used in high-end Burgundy wines and Champagne, so it would be interesting to look into that as well.
What Sur Lie Brings to Wine
Up to this point, we have covered the basics of Sur Lie as typically described in wine-related textbooks.
Since we are here, let us dig a little deeper.
Regarding Polyphenols
Most wines made using Sur Lie are crisp and slightly effervescent.
First, through Sur Lie, amino acids and polysaccharides such as colloidal mannoproteins are generated (from the yeast cell bodies).
Because these polysaccharides adsorb oak-derived polyphenols leached from barrels and form complexes, it is thought that the astringency caused by polyphenols like tannins related to mouthfeel may be softened.
For example, tannins are perceived as astringency when they bind to proline-rich and histidine-rich proteins in the mouth.
If these do not remain, the wine loses its harshness, and it is easy to imagine that it results in a crisp, refreshing drinking experience.
Also, the secret behind the slight effervescence is that yeast that has not fully completed fermentation remains during Sur Lie, leading to refermentation.
Since alcoholic fermentation is a mechanism that breaks down sugar to generate alcohol and carbon dioxide gas, it is thought to finish in a state where a slight effervescence remains as a result.
Impact on Appearance and Aroma
Wines that have undergone Sur Lie tend to have a pale appearance in color and offer a fresh aroma in many cases.
First, regarding appearance, as mentioned earlier, polyphenols in the wine decrease because they are adsorbed by polysaccharides and other compounds during Sur Lie.
Since the browning of white wine is linked to polyphenols in the wine, it is easy to understand that its appearance becomes paler as a result compared to white wine that has undergone typical barrel aging.
Next is aroma.
Generally, because the lees are stirred during Sur Lie, changes occur in reductive sulfur compounds and other elements in the wine, and amino acids released from the yeast cell bodies react with various components in the wine, which is believed to create new flavors.
Furthermore, because the yeast metabolizes oak-derived aroma components such as vanillin into alcohol, suppressing the woody aroma may also be the secret behind achieving a crisp fragrance.
Additionally, there is an interesting study showing that performing long-term Sur Lie on Sauvignon Blanc brings out varietal characteristics well.
It is said that the citrus nuances of Sauvignon Blanc are associated with volatile thiols such as 3MH, and white wines that have undergone Sur Lie somehow carry a hint of citrus nuances. (Though perhaps not all...)
The aroma of Koshu Kiiroka is also related to volatile thiols, and it may be that Sur Lie and Koshu were once again a well-matched pairing.
Sur Lie Is a Wonder
The phrase "Koshu Sur Lie."
Being from Yamanashi Prefecture, it is a term very familiar to me, but delving deeper into it has made me realize its "greatness" all over again.
Sur Lie is a wonder.
It might sound a bit exaggerated, but it has made me want to try various "Koshu Sur Lie" wines again for the first time in a while.
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