Joe Sallustio wrote:

On May 15, 8:08 am, "Paul E. Lehmann"
wrote:
I always look for articles indicating positive
health benefits of drinking wine and indeed
there are many. I recently came across an
article in "Practical Winery & Vineyard" by
Robert Tracy with the heading of "Human health
concerns associated with wine microorganisms"
(pp 96-98).

The partial information I summarize below is
NOT an attempt to start religious wars over
technique or scare anyone but to raise some
concerns that we as wine makers/growers should
know.

Personally, I believe there are "probably" more
health related issues in a can of soda than
some of the material discussed below but
perhaps we can make better wine if we are aware
of some of these facts.

Summary and quotes:

"From a winemaking perspective, there are two
types of compounds produced by wine microbes
that have health implications for the consumer:
biogenic amines and ethyl carbamate. Biogenic
amines have been shown to cause negative
physiological effects in allergic humans (such
as headaches, nausea, hot flashes), while ethyl
carbamate is considered to be a probably
carcinogen to humans. The probable
carcinogenic properties of ethyl carbamate are
based on studies with experimental animals,
there is not direct evidence of it causing
cancer in humans."

"The concentration and type of biogenic amines
vary greatly in wines; however, generally red
wines contain significantly more than white
wines. In addition, there appears to be a
direct correlation between elevated biogenic
amines in wine, wine spoilage constituents
(such as acetic acid, ethyl acetate, butyric
acid, acetoin, and higher alcohol compounds),
and malolactic fermentation."

Because ethyl carbamate is a probable
carcinogen, it is becoming the focus of
international regulation, and so its formation
must be managed properly both in the vineyard
and during the winemaking process."

"Even though both yeast and bacteria can
generate precursors for ethyl carbamate
formation, urea produced from wine yeast is
thought to be the major precursor."

Factors that affect formation

"Throughout the winemaking process, a whole
host of factors can influence the formation of
biogenic amines including:

1) initial microbial populations present on
grapes;

2) presence of precursor amino acids in grape
juice;

3) ageing of wine on wither yeast lees (sur
lie ageing) or lees following malolactic
fermentation;

4) extended grape maceration;

5) spontaneous malolactic fermentation by
indigenous lactic acid bacteria;

6) number of lactic acid bacteria that are
decarboxylase-positive:

7) wine pH;

8) concentration of sulfur dioxide (SO2)
following malolactic fermentation and during
ageing;

9) winery sanitation practices;

10) yeast strain; and

11) fining practices (fining white wines with
bentonite may remove biogenic amines).

Among these factors, it has been demonstrated
that malolactic fermentation is the primary
stage for biogenic amine formation during the
winemaking process.

Ethyl carbamate formation is affected by the
following factors:

1) argine content of grapes;

2) concentration of ethanol;

3) nutrient additions to must, during both
alcoholic and malolactic fermentaitons;

4) yeast straiin;

5) spontaneous malolactid fermentaion by
indigenous lactic acid bacteria;

6) ageing wine on yeast (lees (sur lie ageing);

7) temperature of iwne during ageing and
shipment;

8) duration of wine ageing;

9) wine pH; and

10) wineery sanitation practices."

"Recommendations to prevent formation of
biogenic amines and ethyl carbamate

Biogenic Amines

if possible periodically monitor microbial
populations on grapes to determine risk for
biogenic amine producers.

if possible, assess concentration of primary
precursor amino acids in grapes and must.

avoid spontaneous alcoholic fermentations and
use commercial strains of Saccharomyces
cervisiae that lack or have minimal
decarboxylase activity.

Avoid extended ageing of wine on yeast or
malolactic lees.

Try to minimize extended grape maceration.

Avoid spontaneous malolactic fermentations and
use commercial strains of Oenoccus oeni that
lack or have minimal amino acid decarboxylase
activitry.

Try to avoid higher pH wines (above 3.7) since
they allow proliferation of Lactobacillus and
Pediococcus.

When pH of wine is high, lysozyme can be added
to remove the natural lactic acid bacteria.

Immediately following malolactic fermentaion
and during wine ageing, maintain molecular SO2
levels of at least 0.4 to 0.5 ppm to prevent or
minimize growth of lactic acid bacteria.

Maintan good sanitation practices during wine
production.

Ethyl Carbamate

Avoid argine content of 1000 mg/L in juice.

Avoid excessive nitrogen fertilization of
vineyards.

Periodically monitor nitrogen status of vines
and soil.

Test nitrogen status of juice.

Avoid adding excessive nitrogen supplements; do
not add urea.

Use commercial strains of Saccharomyces
cervisiae that are known to produce low levels
of urea (Premier Cuvee (PdM) or Lallemand 71B)
when juice has a high arginine content.

Avoid ageing wine on yeast lees (sur lie
ageing), which can liberate amino acids and
proteins.

Avoid spontaneous malolactic fermentatons and
use commercial strains of Oenoccus oeni that do
not have ability to produce high levels of
citrulline.

Avoid elevated temperatures during ageing and
shipment of wine.

If wines are going to be aged for an extendd
period of time, it is advisable to periodically
monitor ethyl carbamate levels.

Try to avoid higher pH ines (above 3.7) since
they allow proliferation of Lacto bacillus and
Pedioccus.

Immediately following malolactic fermentation
and during wine ageing, maintain molecular SO2
levels of at least 0.4 to 0.5 ppm to prevent or
minimize growth of lactic acid bacteria.

Maintain good sanitation practices during wine
production."

I realize that amateur winemakers do not have
the resources to monitor all of the above but
we can control a good amount of them.

I encourage anyone who is interested in the
topic
to pick up a copy of the magazine. There are
23
references cited at the end of the article. I
did not quote the article in the entirety but
tried to summarize the main points.

Paul

Fantastic post; thanks. I'll pick up a copy at
Presque Isle.

Joe

Thanks Joe.

I can think of a couple things that we as amateurs
might be able to do without too much trouble -
such as - if doing extended maceration, get a
setup that allows a blanket of Nitrogen or Argon
to be on top of the must.

As far as the aging on lees, I agree that aging on
heavy or gross lees is probably a problem in more
ways than one but I don't know if fine lees is
that much of a problem. The author did not
specify heavy lees or fine lees.

As for the cultured wine yeast and ML culture,
that seems obvious to me but some swear by the
old methods even though they may not produce the
best taste or results and now we know that there
are potential health risks as well. There was one
problem in the article. At one point he seemed
to indicate cultured ML to be a potential problem
but in the other parts he seemed to imply that
only or mostly the "natural" ML could be the
problem to consider.

The pH issue seems right on and my wines have
improved A LOT by maintaining my red wine pH
around 3.5

It was good to know about the problems of high
nitrogen levels both in the vineyard and in the
must creating problems. I think that perhaps
here in the Mid Atlantic some growers jack up
their fertilizer programs and maybe not to the
advantage they think.

I wish he or some other research person would
perform tests on wines with heavy oak and those
not so heavily oaked. I suspect but have not
verified that perhaps the heavy oak is what gives
some people headaches and such. I know some of
my friends say they can not drink red wines but
when they drink mine that have not seen any oak
or very light oak or aging in oak spent barrels
they seem to have no problems.

A lot of the wines at wine festivals around here
taste more like barrels than wine. I have
started to experiment with the oak spirals. My
barrels are long past the point of imparting much
oak. You can hook a stainless wire to them (the
spirals) and to a stainless eye screw in the
bottom of a silicon bung and easily take them out
of a barrel or carboy when it has just the right
amount of oak. This is a lot more difficult to
do with cubes or chips.