Making sparkling wine: disgorging and bottling Pet Nat

The last stage of sparkling wine production often involves a process called disgorgement. The second fermentation has happened in bottle, creating the bubbles. This leaves a lot of dead yeast, and these are collected in the neck of the bottle where they form a plug. This is then frozen, and the crown cap is removed. The pressure expels the frozen plug, and then the wine is topped up and bottled. This is at the Folias do Baco winery in Portugal's Douro wine region.