Anyone have any idea what the taste threshold concentration (in ppm) for
free SO2? I would imagine that bound SO2 would not be a factor since it
is tied up with other molecules.

Thanks!

Joe

"Joe Giller" > wrote in message
...
> Anyone have any idea what the taste threshold concentration (in ppm) for
> free SO2? I would imagine that bound SO2 would not be a factor since it
> is tied up with other molecules.
>
> Thanks!
>
> Joe

Joe,

I don't know a simple answer to your question.

In wine, free SO2 exists in three forms, molecular SO2, bisulfite (HSO3-)
and sulfite (SO3--). The fraction of free SO2 in each form depends on the
pH of the wine. Practically all of the offensive smell (and taste) is
produced by the molecular SO2.

The taste (smell) threshold of molecular SO2 for some people seems to be
about 1.2 mg/l (ppm). But, data from many taste panels indicates
excessive amounts of SO2 may detract from wine quality even when the SO2
smell is not detectable.

To get an idea of the amount of free SO2 needed to produce 1.2 mg/l of
molecular SO2 as a function of wine pH, go down the page here
http://home.att.net/~lumeisenman/chapt6.html
to the pH/SO2 table and multiply the values by 1.5.

lum

Joe,

Lum has really said it all and everything I've read or heard is that
there is tremendous individual variation in the ability to detect free
sulfite, primarily through smell and secondarily through taste.

As one author stated there are some people that have an unusual
sensitivity and have "difficulty finding wines without a detectable
trace of sulfur."

Glen Duff
------------

Lum wrote:

> "Joe Giller" > wrote in message
> ...
>
>>Anyone have any idea what the taste threshold concentration (in ppm) for
>>free SO2? I would imagine that bound SO2 would not be a factor since it
>>is tied up with other molecules.
>>
>>Thanks!
>>
>>Joe
>>
>
> Joe,
>
> I don't know a simple answer to your question.
>
> In wine, free SO2 exists in three forms, molecular SO2, bisulfite (HSO3-)
> and sulfite (SO3--). The fraction of free SO2 in each form depends on the
> pH of the wine. Practically all of the offensive smell (and taste) is
> produced by the molecular SO2.
>
> The taste (smell) threshold of molecular SO2 for some people seems to be
> about 1.2 mg/l (ppm). But, data from many taste panels indicates
> excessive amounts of SO2 may detract from wine quality even when the SO2
> smell is not detectable.
>
> To get an idea of the amount of free SO2 needed to produce 1.2 mg/l of
> molecular SO2 as a function of wine pH, go down the page here
> http://home.att.net/~lumeisenman/chapt6.html
> to the pH/SO2 table and multiply the values by 1.5.
>
> lum
>
>
>

Lum and Glen,
Thanks much! I appreciate your wisdom.

Joe