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Wine (alt.food.wine) Devoted to the discussion of wine and wine-related topics. A place to read and comment about wines, wine and food matching, storage systems, wine paraphernalia, etc. In general, any topic related to wine is valid fodder for the group. |
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![]() I would like to find out what my TCA sensitivity tresshold is (wouldn't you also, by the way)? I have read that some folk are sensitive to concentrations as low as 1 ng/l (nanogram per liter), or possibly even lower, and that others couldn't detect TCA unless they were swimming in a vat of the stuff. Wondering where I can get some ready-made TCA solutions of different concentrations in the range found in corked bottles. Alternative, I guess we can start with, say, a 1000 ng/l solution and dilute it by half, then by half again, etc. I am just concerned that the serial dilution approach increases the error as one goes on, which could be significant if doing it with bad equipment. While we are at it, would the serial dilution be acceptable if done using a 100 ml volumetric flask and a 200 ml volumetric flask? I would take 100 ml of concentration X, put it in the 200 ml flask and fill to volume, resulting in 0.5X. Then, take 100 ml of 0.5X, put it in the 200 ml flask and fill it to volume, resulting in 0.25X, etc., etc. First things first, where can I get a solution of known concentration of TCA (in water and suitable for human sipping and spitting)? Thanks. -- ================================ Check out the MiamiWine blog. http://MiamiWine.com ================================ |
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![]() While we are at it, does anyone know of a lab that will analyse wine samples for TCA contamination for a reasonable price? From time to time, I run into wine that feels contaminated to me but not to other folk. Thus, would like to test them to see whether the TCA sensation is on my nose and tongue or only in my head. On Fri, 10 Nov 2006 15:47:54 GMT, Leo Bueno > wrote: > >I would like to find out what my TCA sensitivity tresshold is >(wouldn't you also, by the way)? > >I have read that some folk are sensitive to concentrations as low as 1 >ng/l (nanogram per liter), or possibly even lower, and that others >couldn't detect TCA unless they were swimming in a vat of the stuff. > >Wondering where I can get some ready-made TCA solutions of different >concentrations in the range found in corked bottles. > >Alternative, I guess we can start with, say, a 1000 ng/l solution and >dilute it by half, then by half again, etc. I am just concerned that >the serial dilution approach increases the error as one goes on, which >could be significant if doing it with bad equipment. > >While we are at it, would the serial dilution be acceptable if done >using a 100 ml volumetric flask and a 200 ml volumetric flask? > >I would take 100 ml of concentration X, put it in the 200 ml flask and >fill to volume, resulting in 0.5X. Then, take 100 ml of 0.5X, put it >in the 200 ml flask and fill it to volume, resulting in 0.25X, etc., >etc. > >First things first, where can I get a solution of known concentration >of TCA (in water and suitable for human sipping and spitting)? > >Thanks. -- ================================ Check out the MiamiWine blog. http://MiamiWine.com ================================ |
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Leo Bueno wrote:
> I would like to find out what my TCA sensitivity tresshold is > (wouldn't you also, by the way)? I dunno. If I was still (blissfully) unaware of my TCA sensitivity, would I be any less happy than I am today? Sounds a bit like the old saw of the tree in the forest (or was that the Pope in the woods?). > Wondering where I can get some ready-made TCA solutions of different > concentrations in the range found in corked bottles. Good question. I'd try a local hobby shop that deals in chemistry sets (if any still exist) or a good pharmacy. As a last resort, if you strike out with that approach, send me an email with a mailing address and I'll send you a bit (it's not trivial for me to send chemicals to private addresses, but it can be done). > > Alternative, I guess we can start with, say, a 1000 ng/l solution and > dilute it by half, then by half again, etc. I am just concerned that > the serial dilution approach increases the error as one goes on, which > could be significant if doing it with bad equipment. > > While we are at it, would the serial dilution be acceptable if done > using a 100 ml volumetric flask and a 200 ml volumetric flask? Serial dilution is a staple of molecular biology labs, Leo. All it takes is an accurate measuring device for liquid volume. I'd do my dilutions by a factor of 10, BTW: twofold is overkill. I'd start with a 10 ppm solution and make 5 tenfold dilutions, giving you a concentration range of 10 ppm down 0.1 ppb. That should cover the full range of physiological response. Get yourself a 10 mL volumetric and a 100 mL volumetric. > > I would take 100 ml of concentration X, put it in the 200 ml flask and > fill to volume, resulting in 0.5X. Then, take 100 ml of 0.5X, put it > in the 200 ml flask and fill it to volume, resulting in 0.25X, etc., > etc. That's the general idea; I'd just change the dilution factor and volumes. Keep in mind that you need all of about 10 microliters of each sample for your test. > > First things first, where can I get a solution of known concentration > of TCA (in water and suitable for human sipping and spitting)? Don't sip it. Just smell it. The "taste" of TCA is almost entirely due to retronasal olfaction anyway, so the smell is all you need to focus on. That also removes the need for USP grade TCA, which would cost you 1000 times as much as reagent grade. Also keep in mind when searching for TCA that it also is the abbreviation for trichloroacetic acid and you _do not_ want to conduct your trials with that! HTH Mark Lipton |
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Leo Bueno wrote
> I would like to find out what my TCA sensitivity tresshold is > (wouldn't you also, by the way)? Yes, I'd like to. One thing comes to mind: a good level of TCA perception starts when you are able to distinguish between corked wines who can be drank and corked wines to pour down the sink. The drinkable ones are those where the TCA hasn't already demaged the wine, killing most of it's aromas, and the undrinkable ones are those who just smell TCA and alcohol. -- Vilco Think pink, drink rose' |
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On Sat, 11 Nov 2006 15:04:02 +0100, "Vilco" >
wrote: >Leo Bueno wrote > >> I would like to find out what my TCA sensitivity tresshold is >> (wouldn't you also, by the way)? > >Yes, I'd like to. One thing comes to mind: a good level of TCA >perception starts when you are able to distinguish between corked >wines who can be drank I don't believe such wines exist, unless your definition of drinkability is radically different from mine. >and corked wines to pour down the sink. A bottle of corked wine should be taken back to where you bought it, if at all practical. If they won't take it back, find another place to buy your wine. >The >drinkable ones are those where the TCA hasn't already demaged the >wine, killing most of it's aromas, See earlier comment >and the undrinkable ones are those >who just smell TCA and alcohol. I'll drink to that. Vino |
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Vino wrote
>> Yes, I'd like to. One thing comes to mind: a good level of TCA >> perception starts when you are able to distinguish between corked >> wines who can be drank > I don't believe such wines exist, unless your definition of > drinkability is radically different from mine. I drank a bottle of Pignoletto some days ago, the nose was eprfect and the palate too, at first tasting. After a second sip I didn't notice anything and then smelled the cork: it smelled bad, so I tried the wine again, there was only a very far cork note in the mouth, while the aroma and taste of the wine were still presente. This wine was, I guess, in an initial stage of contamination, which left a very small trace of TCA and hadn't enough time to spoil the wine. The cork taste was very hard to feel, I had to concentrate on it and after this I could drink the wine wothout feeling cork. This is what I consider a corked wine which can be poured in glasses instead of sinks. -- Vilco Think pink, drink rose' |
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On Sun, 12 Nov 2006 22:36:07 +0100, "Vilco" >
wrote: >Vino wrote > >>> Yes, I'd like to. One thing comes to mind: a good level of TCA >>> perception starts when you are able to distinguish between corked >>> wines who can be drank > >> I don't believe such wines exist, unless your definition of >> drinkability is radically different from mine. > >I drank a bottle of Pignoletto some days ago, the nose was eprfect and >the palate too, at first tasting. After a second sip I didn't notice >anything and then smelled the cork: it smelled bad, so I tried the >wine again, there was only a very far cork note in the mouth, while >the aroma and taste of the wine were still presente. This wine was, I >guess, in an initial stage of contamination, which left a very small >trace of TCA and hadn't enough time to spoil the wine. The cork taste >was very hard to feel, I had to concentrate on it and after this I >could drink the wine wothout feeling cork. This is what I consider a >corked wine which can be poured in glasses instead of sinks. The wine in a corked bottle is never going to be as good as the same wine from a botle that is not corked. So you are not getting the wine that you paid for. That, to me, is reason enough to return the bottle (if that is practical). Drinkability is a matter of personal taste. There have been times where I have gotten partway into a bottle before realizing it was corked. There is no way I could enjoy the remainder of the bottle. It's like getting an "off" taste from a piece of meat or fish. Maybe it's only one spot, but the rest of the piece won't taste the same after that. vino |
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On Fri, 10 Nov 2006 11:12:11 -0500, Mark Lipton >
wrote: > >> Wondering where I can get some ready-made TCA solutions of different >> concentrations in the range found in corked bottles. > >Good question. I'd try a local hobby shop that deals in chemistry sets >(if any still exist) or a good pharmacy. As a last resort, if you >strike out with that approach, send me an email with a mailing address >and I'll send you a bit (it's not trivial for me to send chemicals to >private addresses, but it can be done). > No need to go through the trouble. Sigma Aldrich will sell a 1ml solution for about $45. I would prefer to pay less, but what the heck. -- ================================ Check out the MiamiWine blog. http://MiamiWine.com ================================ |
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