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