Port Wine Information

Question: Whats the white powdery substance in between bottle cap of port wine and bottle head?

(Posted by: Cnl Delta on 2008-12-30 05:05:41)

I opened a capped bottle of port wine and noticed a white powdery substance on the ridges of the bottle where the cap twists onto the bottle. What is that white substance and is it safe if some of it flakes into a glass of wine while pouring the wine? The wine is stored on the shelf at 90 fahrenheit/ 32 celsius before opening. The external bottle looks fine. After uncapping the bottle, I noticed white fleck/ matter on the part of the bottle (ridges) where the cap screws onto the bottle.

Posted by: dogglebe on 2008-12-30, 06:25:51

The powder is either sodium metabisulphite or potassium metabisulphite. It's used to sanitize the bottle and cap, and also used to preserve the wine. It's harmless but, if you want, you can rinse it from the cap.

Posted by: Klaus on 2008-12-30, 06:16:49

The powder can only guess... But one thing can say sure, your storage temperature for the bottle was utterly too high, it should have been no more than around 16-18 Celsius degrees only. While opening the bottle, should sweep all suspicious dust from the bottle with paper or cloth before completely opening the bottle, to avoiding impurities from entering into the bottle.