Cork Taint - what one winery does

I just saw this and thought it interesting enough to share. Honig Vineyard & Winery (no relation that we know of, as they made clear when I asked for a discount ), explains on their blog how they work to prevent cork taint.

Honig winemaker, Kristin Belair, pre-screens each individual cork in a vodka-water solution overnight. The vodka is diluted to a concentration of about 13% ethanol alcohol to mimic wine conditions. After soaking the corks Kristin evaluates them for off aromas. If the corks have any off aromas, she rejects the entire lot. Our trials have consistently proved to us that natural or bark cork is the best closure for our red wines.

Read the whole thing. It's interesting.

Hmm, I reckon there's a typo in that article. It would make more sense to say:

"Honig winemaker, Kristin Belair, pre-screens each batch of corks by soaking a sample in a vodka-water solution overnight. The vodka is diluted to a concentration of about 13% ethanol alcohol to mimic wine conditions. After soaking the corks Kristin evaluates them for off aromas. If the corks have any off aromas, she rejects the entire lot."

As the article stands, she'd need a very small bottling run, a lot of vodka, a lot of glasses, or sense of smell that doesn't get attenuated by constant exposure to TCA (or a combination of the preceeding)

As Nayan said, it looks like this blog was sloppily written and what this winemaker is doing is evaluating incoming batches of corks by testing samples for cork taint. Assuming that's the case, this is a fairly common approach. The assumption is that tainted corks are distributed randomly through the batch, so testing a statistically sufficient sample can establish with a certain statistical confidence that the whole batch is taint-free. It is highly unlikely that she's testing every cork.

It's pefectly clear from the blog, but you need to read the sentence before the para quoted in this thread: "Cork Supply sends us fifty corks from each lot of ten thousand corks prior to selling them to us." It is these corks that are tested individually, and the lots of 10,000 that are potentially rejected (before they are delivered). So it's a 0.5% sample that's tested.

It's pefectly clear from the blog, but you need to read the sentence before the para quoted in this thread: "Cork Supply sends us fifty corks from each lot of ten thousand corks prior to selling them to us."

I totally missed that sentence when I read through

Having said that, I wouldn't (and don't) trust a supplier to send me a randomised sample.

Having said that, I wouldn't (and don't) trust a supplier to send me a randomised sample.

Yes I was thinking that. And what do you think happens to the rejected batches?

And what do you think happens to the rejected batches?

Judging by recent tastings I reckon they end up in India and China

This is fairly standard practice these days for most wineries that use a lot of cork. One thing that would be interesting to see is exactly how many batches they reject? And what percentage of corked wines do they STILL have and can they trace these back to specific lots to see if they were simply off . . .

I also like the final statement about this process confirming that cork closures are right for them . . . Why?

There are visible batch numbers on the corks, presumably. All of them, not just the 50 you get sent. And the cork supplier has over-printed all 10,000 corks with the batch number before they send you the 50, yes?
Or is the winery so trusting...?
cheers,
Graeme

Graeme - you took the words right out of my mouth. What is the provable connection between the samples and the entire batch?

I think this is great, that the cork suppliers (reputable ones anyway) are cooperating and accepting the wine producers request. This shows that they are now seriously trying to reduce the chance of TCA tainted wines. First I think one should note that the cork industry is “tightening their belt” especially when it comes to QC. They have ISO regulations when it comes to inspection. Surely instead of using sensory analysis they have moved on to gas chromatography-mass spectrometry. Upon request they have to supply the buyer of the corks with C of C and inspection report.
The issue here is that instead of doing an individual cork soaks (just too expensive) they use a sample consisting of a 50 cork group soak. The number of samples taken is determined by the number of bales in a lot (1 bale = 5,000 corks, a lot can not exceed 50 bales, 250,000 corks). They use a two stage inspection or analysis, initial and secondary. If the initial analysis is questionable they perform a secondary analysis taking additional samples (the number of additional samples (1 sample = 50 cork group soak) taken will again be determined by lot size). What the wine makers are afraid of is that when doing group soaks you might get “lower” results because “clean” corks will absorb some TCA. So they rather just “double-check” using “old-faithful” and the traditional method of detecting TCA, their own noses and the sensory analysis.

Salute

Many thanks for that Victorwine. I have many questions, but probably more than can sensibly be discussed here. Do you have any more detailed (publically accessible) references on QC of corks? As technical as you like - I have no fear of chemistry and statistics. Cheers, Steve.