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