Thursday, October 25, 2012

TCA Cork Taint and How did Trichloroanisole get in my Wine?

Trichloroanisole is found produced by fungus, often on
corks. 
Ever bought a bottle of over-price old wine and found that the bottle was spoiled? The fungus growing on the cork produces trichloro-anisole which wine-jocks say smells like wet dog or damp basement.

This brings up several issues: why arn't the corks sterilized? And where does the chlorine come from to make the trichloro-anisole? And most importantly, how poisonous is trichloro-anisole?

Why are natural corks sterilized? I am sure people try but cork is even worse than wood for sterilization. Cork might be quant, but it isn't a very good material, and probably should not regarded as food grade. Old fashion traditionalists need to grow up.

Some say that the source is chlorine-containing air pollutants on the trees that grow the cork. It is more likely that it is due to the wood preservative trichloro-phenol that is used with wood barrels. Another source of chlorine is from the use of bleach and related oxidizers as cleaning agents.

Chlorine bleach reacts with wine residue and living microbes to make chlorinated byproducts -- some of which may be carcinogenic. You need to rinse a lot after using bleach, and dirt that reacts with bleach may be hard to see -- but still could contain chlorinated compounds that are harmful. Trichloro-anisole is not carcinogenic however -- so don't worry.

The alternative to chlorine bleach is sulfite containing materials, and these make a familiar rotten eggs smell if over used. Not as dangerous as trichloro-anisole, but less appetizing too. The best is using ozone but that is not practical at home, or is barely practical. More on that later. Another non-toxic sterilization agent is hydrogen peroxide.



Sunday, October 7, 2012

2012 French Colombard

Went to the wine store, and as is my custom, I walked around and looked at the grapes first. I wanted white grapes, and it was picked over as it is late in the season. They had seedless Muscato which I did not want and French Colombard. I tasted the French Colombard grape, and it was delicious. I bought four cases and brought them home.

When I got home I looked up French Colombard, and found it is popular, but not highly regarded. On the other hand it did taste good to me. It seems it is easy to grow but critics don't think it works well as a varietal wine.

I crushed and pressed the grapes. I took the raisins in the crates, and soaked them overnight in water to extract the sugar. I want to stress the citrus and floral notes so I added orange rind and columbine tea.

Sugar content of the juice with the raisin water was 24.3% which was determined from the 1.095 g/ml density and the 22.6 degree Brix refractive index. My target alcohol content for this wine is 12.5% alcohol which corresponds to 24.3% sugar so I added 2.1% cane sugar (710 g = 2.1/100*8gal*3.8L/gal*1.09g/L).

2012 French Colombard Wine Recipe

144 lb French Colombard Grapes (crushed)
9 g potassium sulfite (to kill wild yeast)
710 g cane sugar
10 g Pectic enzyme for clarity
6 g potassium carbonate (to reduce acidity)
Rind from three oranges
8 Celestial Seasonings Columbine tea bags
6 Twinings Echinacea & Raspberry tea bags
16 g yeast energizer
1 Packet Red Star Pasteur Cote des Blanc yeast

After one week of fermentation, I put 32 liters into glass for aging. Fermentation was nearly done, and the gas bubbling was pretty slow at 7 days. 

I have thought a lot about how to make the wine more floral, and herbal tea sees sensible. I am a little concern as I think the Columbine tea really tastes like straw more than flower, so we will see.


========================== 2 week update=================
I waited six days before transferring it to my glass demijohn, but now it is barely bubbling (fermenting.) I am worried that the fermentation has stopped.