As I set about to run some trials in disgorging and adding dosage to riddled bubbly—two critical steps in the méthode champenoise (aka traditional method) production of bottled-fermented sparkling wine—I was reminded of an interesting question asked by an attendee at my seminar at the last WineMaker Magazine Conference in Napa Valley: “Why not simply place bottles upside down in carton boxes instead of having to riddle each bottle every day for 21 days?”
Tough question to answer without looking at the physics of what is actually happening during riddling—the process of channeling bottle-fermentation lees down to the neck portion of the upside-down bottle to allow the lees to be expelled by disgorgement and produce a crystal-clear bubbly. A poorly riddled bottle can spell disaster, and turning bottles over to let the lees flocculate without proper riddling simply won’t work.
If bottles are turned over in a case, yes, most of the lees volume will find its way to the neck; but “most” is not good enough. The problem is that some lees particles will cling to the glass—just hold up the bottle against a strong light source and you will see what I mean. These fine lees particles now become nucleation sites for the dissolved carbon dioxide gas. Once the bottle is disgorged and the lees are removed, microbubbles will rapidly form and nucleate at these sites, and then quickly rush up to the surface of the wine in the bottle, and cause the wine to gush out uncontrollably. This is further exacerbated when adding the dosage.
Let’s look at this phenomenon a little closer....