A cautionary tale of mice, microbes, and mechanical harvesting

Short: A recent medical report indicates that fresh juice from mechanically harvested grapes can (on very rare occasions) carry infectious diseases from animals picked up and crushed by harvesting machinery.

Long: Winery work is dangerous. Especially (but not only) during harvest, wineries are production facilities with heavy objects, slippery floors, potentially hazardous chemicals, machinery with moving parts and, often, forklifts. The positive side of that situation is that winemaking professionals know that winemaking — like any similar form of factory or food production work — is dangerous, and they take steps to mitigate risks. An enormous part of mitigating risks is knowing what those risks are, which is why a recent letter to the editor about mechanical harvesting in the New England Journal of Medicine is worth knowing about.

Potential dangers of mechanical harvesting are usually discussed in terms of dangers to the grape vines (of being beaten up by the machines), to the wine (though mechanical harvesting is far from being always a bad thing for quality) or, maybe, to vineyard soil compressed by heavy machinery or animals caught by harvesting equipment. Endangering animals, however, might on rare occasion also endanger humans — and not just if a harvester has an inadvertent run-in with a neighbor’s cat. Some critters commonly found around vines can carry diseases that affect humans.

When six of 29 harvest workers employed at a vineyard in Rhineland-Palatinate, Germany, came down with the same symptoms — trouble swallowing, swollen lymph nodes in the neck, diarrhea, general aches and chills — regional specialists worked them up for infectious disease and came down with a diagnosis of tularemia. Tularemia is what happens to humans when infected by a bacteria, Francisella tularensis, carried by some rabbits and rodents. Most cases occur in hunters. Symptoms vary with how the bacteria entered the body, but the bacteria are never transmitted from human to human, only from animal to human. Or, in this case from animal to grape juice to human. All six workers who became sick remembered drinking fresh juice from the same load of mechanically harvested grapes before becoming sick. Epidemiologists found DNA from F. tularensis and from common field mice in the freshly fermented wine made from that batch of grapes.* Their concluding hypothesis was that an infected mouse or two had been picked up by the harvester and crushed along with the fruit, contaminating the fresh juice.

The wine was confiscated and prohibited from sale, needless to say, though probably without real cause. Infectious disease transmission via wine is unheardof, thanks to the combination of high alcohol and low (acidic) pH that makes wine an inhospitable environment for could-be pathogens. Though I don’t know (and I’m not sure anyone knows) about F. tularensis‘s ability to survive in wine, it’s important to note that the epidemiologists found F. tularensis DNA in the wine, not intact infectious bacteria, and that workers suffered from drinking grape juice, not wine.

The authors of the NEJM letter — most of them German public health officials — concluded that “raw food stuff should be treated before consumption.” If that means “we recommend that you don’t drink fresh juice from mechanically harvested grapes,” that sounds pretty reasonable. Like recommendations about not eating raw cookie dough, many will choose to accept the risk; a lot of us will accept the very small chance of getting ill from bacteria in raw eggs or raw flour for the sake of the certain pleasure of enjoying delicious cookie dough. But, importantly, we know that the risk exists, and if we become sick we might even think to tell our physician about what we ate, which could speed up receiving appropriate treatment.

Tularemia is endemic but rare across the United States and Europe (it’s mostly a Northern Hemisphere disease), with only a few hundred cases per year across the United States. The lesson here would NOT seem to be “don’t drink fresh mechanically harvested grape juice or you might get tularemia” but, rather, “know enough about your environment to have a clue about what might have happened on the very, very rare occasions that something goes wrong.” Also, watch out for mice.


*Did any of the harvest workers remember seeing field mice in the vinyard, and did anyone in the cellar see a dead mouse or two pour into a fermenting vat? Unfortunately, the public health officials who wrote the report didn’t say.

Does (diet-branded) Cense wine make sense?

The marketing story: Cense Marlborough sauvignon blanc is the first Weight Watchers-branded wine, made by Truett-Hurst, a holding company for California-based wine production and branding operations. Cense has 85 calories per 5 oz glass,* equating to 3 Weight Watchers’ “points.” The partners expect to add other wines to the brand line-up including (surprise, surprise) a rosé.

The numbers: Cense is a reduced alcohol wine. The brand also hooks its diet-friendly message on claims about no added sugar, but dry table wines essentially never contain added sugar, and the small fraction of residual sugar in the vast majority of table wines makes an insignificant calorie contribution. “Lower calorie” is just alternate marketing for “lower alcohol.”

Since ethanol and sugar are the only signficant sources of calories in wine, estimating the calories in your glass of non diet-branded wine is simple.** (Color only matters in that whites are often, though not always lower in alcohol than reds.)

Calories in a 5 oz glass = (alcohol on the label as a decimal)(785) + (sugar in grams/liter) X (.568)

A 12% dry wine with .5% residual sugar clocks in at just about 100 calories per 5 oz. Make that 13.5% – the starting point for sauv blancs from Kim Crawford up to Cloudy Bay and Greywacke – and the same 5 oz glass comes up to 110 calories. By drinking Cense, you save about 35 calories per glass, the equivalent of about 5 almonds or one and a half medium-sized carrots.

The analysis: Does Cense make sense?

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Vegan wine: Do the yeast count?

The vegan wine conversation usually goes like this:

“So, I’m looking for a vegan wine…”

Wait; isn’t all wine vegan?”

Dude, no. A lot of wine is clarified using egg whites, or gelatin, or a milk protein called casein, or this stuff from fish bladders called isinglass. Wine isn’t just fermented grapes, you know. Winemakers can use a bunch of other stuff for processing steps, and they often don’t have to put it on the label.”

Wow. I never knew that. I don’t want animal products in my wine! So, are any wines really vegan?”

Yes! Not all winemakers use those products. Some use a kind of powdered clay called bentonite, and some just let the wine sit for a longer time so the particles settle out by gravity. But all of that isn’t always on the label, so you have to look kind of carefully for “vegan friendly” or “no animal products” or “fined with bentonite” on the label or something like that. Some big brands, like Bonny Doon, are known for making only vegan wine, so that makes things a little easier.”

That whole dialogue sidesteps a crucial question: what counts as an animal? And what counts as exploiting it? Talking about whether wine is vegan, in other words, should sound more like talking about whether honey is vegan. Do the bees count? Do the yeast count? Are they being exploited?

A Slate article about the vegan honey question way back in 2008 makes the central point: “any vegan who eats honey but avoids milk is making the tacit assumption that the pain experienced by a bee counts for something less than the pain experienced by a cow.” From caring about bees, it’s a short and slippery slope to caring about silkworms, or yeast or, heck, plants. And then where does that put the conscientious vegan?

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