campden tablets

[nman13]

Hi,

I was told that after first crushing your grapes add one campden tablet per gallon of must and shut the lit of the bucket for 24 hours for all yeasts and bacteria to be killed. Do I need to wait the full 24 hours? i wanted to add the wine yeast after around 12-16 hours and was wondering if i could or not. Thanks a lot.

Also after adding the campden tablets to my must i realized it changed from a purplish color to a brown one. Is this normal?

 

[DoctorCAD]

Campden does odd things to colors, so that is OK.

I'd still wait 24 hours to let the campden dissipate so it doesn't stun the good yeast, but 16 hours might be OK. Worst case is a longer time until the good yeast starts multiplying and making alcohol.

 

[shelly_belly]

From "The Home Winemakers Manual" by Lum Eisenman

Most winemakers add an initial dose of 30 to 50 milligrams of sulfur dioxide per liter when grapes are crushed to help control native yeast. Contrary to much home winemaking literature, sulfur dioxide added at crush does not kill native yeast, but it does greatly diminish their activity for several hours. Commercial wine yeast has considerable tolerance to sulfur dioxide and remains active in the presence of normal amounts of sulfur dioxide. When commercial yeast is added to juice containing reasonable amounts of SO2, a large population of the added yeast quickly develops while the native yeast is inactive. The commercial yeast then dominates the fermentation, and this is why all wine yeast manufacturers recommend adding yeast immediately after sulfur dioxide additions are made to juice or crushed grapes.

 

[KBentley57]

for anyone who is curious, each campden tablet weighs about half a gram. I suppose it's 10x mass is to account for it not being completely made of SO2

 

[DoctorCAD]

for anyone who is curious, each campden tablet weighs about half a gram. I suppose it's 10x mass is to account for it not being completely made of SO2

SO2 is a gas.

(from the interweb)

Potassium metabisulfite, K2S2O5, also known as potassium pyrosulfite, is a white crystalline powder with a pungent sulfur odour. The main use for the chemical is as an antioxidant or chemical sterilant. It is a disulfite and is chemically very similar to sodium metabisulfite, with which it is sometimes used interchangeably. Potassium metabisulfite is generally preferred out of the two as it does not contribute sodium to the diet.
Potassium metabisulfite has a monoclinic crystal structure which decomposes at 190 °C, yielding potassium oxide and sulfur dioxide:

 

[nman13]

hey thanks for your help. when i opened up the bucket i realized that only the top layer was brown and the rest was purple. Does this mean that i did not mix enough and the campden tablets did not get to the entire solution or am i okay?