Showing posts with label wine chemistry. Show all posts
Showing posts with label wine chemistry. Show all posts

Tuesday, January 18, 2011

Wine Fact #2 - It's not broken glass!



Many years ago when I was working in an un-named three hat restaurant in Melbourne, I was confronted during service with what can only be described as one hysterical woman who single handedly brought service to a screeching halt! The problem you ask, and I quote, “Ohh my GGGGOOOODDD!! (God not good people) There are smashed shards of glass in my wine. Ohhhh GGGOOODDD, someone call an ambulance!!!”

A good 15 minutes later said woman had composed herself and had sheepishly decided not to sue ‘the pants’ off of said restaurant. What were initially thought to be shards of glass were merely soluble crystals of Potassium Bitartrate, or KOCO(CHOH)2COOH for all you science geeks out there. From here I’ll let Mr. Rankine take over from 'Making Good Wine',





When the wine is cooled the solubility limit of potassium bitartrate is exceeded and some comes out of solution as a crystalline deposit. When this happens to white wine in the bottle the deposit is unsightly and may be mistaken by the uninitiated for broken glass .... Potassium bitartrate is present in the grapes, partially precipitates as argols during fermentation because of its low solubility in alcohol, and is present in the young wine as a saturated or even a super-saturated solution in excess of its normal solubility.”

The crystals are usually present on the under-side of corks and sometimes will settle at the bottom of the wine bottle.

So there you go. Doesn’t exactly say it’s not going to kill you, but when Rankine refers to it as “unsightly”, well “Sex in the City 2” was unsightly but that didn’t kill anyone – no-one we know of anyway. And that’s a wine fact.