So I'm staring at the results from a MLF test and I'm wondering if
there's a faint indicator of malic acid or it's just the lights.
Paper chromatography seems very qualitative - I'm 90% sure that malos
are complete as I don't see any dots for malic acid, but it's all very
blue/yellow/green and fuzzy. Even the testing documentation stated
that when there is no longer any dot there still may be some malic
acid left. When does one declare victory?

"Michael Brill" > wrote in message
om...
> So I'm staring at the results from a MLF test and I'm wondering if
> there's a faint indicator of malic acid or it's just the lights.
> Paper chromatography seems very qualitative - I'm 90% sure that malos
> are complete as I don't see any dots for malic acid, but it's all very
> blue/yellow/green and fuzzy. Even the testing documentation stated
> that when there is no longer any dot there still may be some malic
> acid left. When does one declare victory?

Hi Michael,

You're correct that paper chromatography is not sensitive enough to be
sure that all the malic acid is gone. To be sure, you need an enzyme test
from a lab or possibly the malic acid test strips from www.accuvin.com. (I
have some of the latter, but have not tested them against known standards
yet. ) What most people do is just confirm that malolactic is occurring and
has come near completion, then bulk age for about a year and assume the wine
is stable. Other options are sterile filtering and adding lysozyme before
bottling to be safe. I use the bulk age then lysozyme approach, but it's
expensive.

Happy Holidays,

John

"John DeFiore" > wrote in message >...
> You're correct that paper chromatography is not sensitive enough to be
> sure that all the malic acid is gone. To be sure, you need an enzyme test
> from a lab or possibly the malic acid test strips from www.accuvin.com. (I
> have some of the latter, but have not tested them against known standards
> yet. ) What most people do is just confirm that malolactic is occurring and
> has come near completion, then bulk age for about a year and assume the wine
> is stable. Other options are sterile filtering and adding lysozyme before
> bottling to be safe. I use the bulk age then lysozyme approach, but it's
> expensive.
>
I wonder how accurate the various accuvin tests are. Even though you
haven't benchmarked them, do you have a feel for their accuracy?
Doing it at a lab will cost a few hundred dollars for all of my wines
(about 10) and if the answer is no, then I'd have to do it again.

> Happy Holidays,
>
Thanks, I'm off to wrap presents now... wonder if people will like
mostly complete MLF, green, slightly stinky, 3 month old wine? ;-)

....Michael

"Michael Brill" > wrote in message
om...
> >
> I wonder how accurate the various accuvin tests are. Even though you
> haven't benchmarked them, do you have a feel for their accuracy?
> Doing it at a lab will cost a few hundred dollars for all of my wines
> (about 10) and if the answer is no, then I'd have to do it again.

I don't have a feel for the accuracy- Each of their products is based on a
different approach- The PH strips seem fairly accurate, though I only use a
very good PH meter with a high quality probe. The TA measurement kit I did
benchmark against titration with NaOH, and the Accuvin test gives a good
general indication. I don't think anybody can say how good the malic acid
test kits are without running some controlled tests or without some data
from the manufacturer. The attractive thing is that the claimed sensitivity
is much better than paper chromatography, so perhaps this year I'll break
down and do some benchmarks. I'll post the results if I do.

Best wishes,

John

One declares victory when the cost of the wine per bottle is less than 30%
of the cost of testing. Paper chromatography has been shown to be the least
expensive way of testing, but the most expensive in terms of lighting needs.
Replace the bulb by which you read the strip with a 30 watt appliance light;
the fuzzy stuff will go away. Reynad Gallo knew this technique.

--
Bob Helgoe

"Michael Brill" > wrote in message
om...
> So I'm staring at the results from a MLF test and I'm wondering if
> there's a faint indicator of malic acid or it's just the lights.
> Paper chromatography seems very qualitative - I'm 90% sure that malos
> are complete as I don't see any dots for malic acid, but it's all very
> blue/yellow/green and fuzzy. Even the testing documentation stated
> that when there is no longer any dot there still may be some malic
> acid left. When does one declare victory?

Just a quick comment from a newbie. This paper chromatography sounds
like a technique used in chemistry--thin layer chromatography. Place
a drop of your sample on a small sheet and run it in a solvent,
visualize with UV or an indicating reagent. All types of
chromatography are sensitive to concentration so red, for example, may
show up as orange or yellow depending on how much 'stuff' you have.
No spot may appear because there is too little indicator (not usually
the case) or the compound is in very low concentration. What remains
constant (in a given solvent system) is the distance that a compound
will travel on the paper. Everything else is qualitative.

If you have big fuzzy spots (as it sounds like you do), dilute the
solution a little bit before you apply it to the paper. I'm guessing
that your referring to a UV lamp in which case, UV is pretty sensitive
so you should be able to see more clearly with a less concentrated
solution.

On 23 Dec 2003 22:16:41 -0800, (Michael Brill)
wrote:

>So I'm staring at the results from a MLF test and I'm wondering if
>there's a faint indicator of malic acid or it's just the lights.
>Paper chromatography seems very qualitative - I'm 90% sure that malos
>are complete as I don't see any dots for malic acid, but it's all very
>blue/yellow/green and fuzzy. Even the testing documentation stated
>that when there is no longer any dot there still may be some malic
>acid left. When does one declare victory?