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.