Fruit and roots for days – Physics World

Taken from the March 2020 issue of Physics World. Members of the Institute of Physics can enjoy the full issue via the Physics World app.

Is “biodynamic wine” is stuff or nonsense? In this article (originally published in Lateral Thoughts, Physics World’s regular column of humorous and offbeat essays, puzzles, crosswords, quizzes and comics, which appears on the back page of the print edition) Caitlin Duffy takes a scientific look at the agricultural process popular in the wine industry

(Courtesy: iStock/bluejayphoto)

As an undergraduate student at the University of St Andrews from 2015 to 2019, my thirst for knowledge, and fine beverages, was quenched by two part-time jobs. The first was as a tour guide at Kingsbarns whisky distillery, and the second was as a retail assistant in a local drinks shop. Indeed, I would frequently joke that I was actually paid to drink, but both jobs gave me a plethora of skills profoundly useful for physics – I gained confidence in public speaking, learnt time management, and got used to dealing with challenging people. What’s more, I always know which beverage to choose for any occasion.

One evening in the shop during our organic and vegan wines month, my boss – a sponge of booze information – set about educating us on the world of “biodynamic” wine-making. The idea is that wine-makers plant, grow and even advise consumption depending on the phases of the Moon with respect to the Sun, constellations and the planets. Biodynamic agriculture was pioneered by Austrian philosopher and esotericist Rudolf Steiner, in the 1920s. Its application to the wine industry is credited to German enthusiasts Maria and Matthius Thun, who practised biodynamic gardening. They eventually applied their 50 years of research and experimentation to publish the first “biodynamic wine calendar” in 2010.

Days are split into four distinct categories: fruit days, root days, leaf days and flower days. In brief, fruit days are those on which the Moon rises through “fire” constellations – they correspond to both good harvesting and optimal drinking days. Flower days – when the Moon rises through “air” constellations and plants should be left to their own devices – benefit aromatic wines. Leaf days are those on which the Moon rises through “water” constellations, and plants should be watered on these days. Finally we have root days, when the Moon rises through “Earth” constellations and all the “lunar energy” is concentrated in the roots of the plant – these are the worst of all for drinking wine.

I was sceptical and craved some scientific evidence – surely, given that large supermarket chains, and even some Grand Cru Bordeaux vineyards, are coming out as biodynamic converts, there must to be some credibility to these biodynamic claims. My scientific intuition was telling me that it was as much a genuine prospect as homeopathy or astrology, and was perhaps evidence of a large-scale placebo effect. Still, as an open-minded scientist, I was prepared to give biodynamic wine the benefit of the doubt.

To my surprise, there was only one legitimate peer-reviewed paper on the subject published in PLOS One in 2016, alongside many biased individual studies. The paper, entitled “Expectation or sensorial reality? An empirical investigation of the biodynamic calendar for wine drinkers”, tested 19 professional New Zealand wine critics, who tasted 12 pinot noirs on two fruit and two root days. The study found that while the wines tasted different on each day, there was no correlation between a more negative experience and root days, or vice versa, as suggested by the biodynamic calendar.

Critics of the paper within the biodynamics community claimed that pinot noir was too dull a grape to have any marked differences, and that the study would have benefited from an aromatic white that would “sing” on fruit days; or a tannic red to taste astringent on root days. The biodynamic enthusiasts’ studies were entirely dependent their preconceptions: there was a suspicious correlation between calendar followers tasting a difference and sceptics not; there was even some divide within the followers themselves with some admitting “wine doesn’t taste bad on root days, it just tastes better on fruit days” (with no evidence provided). Additionally, there are some obviously fundamental flaws in both the experiment and the calendar itself: are four tasting days in total sufficient? How were uncontrollable variables accounted for? Moreover, a fruit day can change into a root day at any minute; would that mean that in an instant a wine would turn from tasting of blackcurrants to bell pepper?

In essence, there are many different variables that can influence the drinking of a wine. Due to the volatility of alcohol, factors such as poor weather and low atmospheric pressure temperatures have a significant impact on taste, such that aromatics taste stiff, and flavour is subdued. Also, drinking even the best of wines in a foul mood never bodes well for true appreciation. Furthermore, bottle storage and wine temperature will affect aromatics: a riesling might taste like burnt plastic when warm, like honey blossom at optimal temperature, and like acid when chilled. Most importantly, drinking should be done in good company and in a comfortable environment in order for you to feel most at ease; being anxious, irate or distracted will hurt the drinking experience.

Perhaps we should transfer our robust scientific methods from exoplanets and lasers to wine – if nothing else, these studies would make for an interesting social activity at conferences

With so few scientific studies, perhaps we should transfer our robust scientific methods from exoplanets and lasers to wine – if nothing else, these studies would make for an interesting social activity at conferences. Until the biodynamic way of drinking has been rigorously tested scientifically, I encourage you to drink whatever you want, whenever you want, and however you want (safely). It’s your wine and you shouldn’t have to wait until Jupiter’s four moons are visible and form a direct line to Orion’s belt to enjoy it.

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