The Sweet Potato: An International Investigation

From the Irish Potato Famine to French Fries, this simple tuber has made impressive and unrivaled intercontinental sociopolitical statements for hundreds of years. It was first cultivated in South America somewhere in southeastern Peru and northern Bolivia from 3-7,000 years ago, but probably grew wild as far back as 13,000 years prior. Spanish conquistadors discovered and brought them to Spain in the late 1500s, after which a slow steady spread across Europe saw the potato in Ireland, Holland, France and Germany by the mid 1600s. There isn’t a more versatile or sought after root crop whose cultivars continue to gain popularity and recognition around the world, most recently the sweet potato.

Why is there so much variation in flavor, texture and color? This confusion stemmed from a haphazard observation of my potato consumption during the past year, as I moved from the fall season in Southern France to winter in Berlin, then spring in New York. When I tried to prepare them the same way as I had in previously, these potatoes were dull in color and nearly flavorless, sort of flat tasting. It was confusing since I (naively?) imagined the birthplace of the potato being the source of the tastiest ones. I really wanted it to be true. Maybe I never noticed it before, but after living abroad and coming back it was a pretty sharp contrast. I missed the vibrant, almost florescent orange, with a rich, complex smell and taste. So I went down a rabbit hole because there was so much I didn’t know and needed to understand in order to try to answer this.

WHO IS POTATO

Part of the tuber family, it grows underground as essentially a food reserve or main organ for the leafy plant that emerges above. It’s a hardy, highly adaptable, nutrient dense vegetable, an ideal essential food that offers a variety of vitamins and minerals:, including vitamin A & C, potassium and fiber.

Tubers prefer well-drained, deep but loose soil, high in organic matter. Loam, a mix of sand/silt/clay in varying ratios, seems to be ideal and I found it to be commonly mentioned as the prominent soil structure for planting them across the US and EU. It makes sense that fluffy soil gives roots the wiggle room to dig and reach which is why dense, packed, clay-forward soils are not ideal.

A North Carolina Sweet Potato Farm

There are many varieties of sweet potato, some of which have yellow or orange flesh (generally from the US) and others have white flesh (from places like Israel, Honduras, China and Egypt). Since the EU imports the majority of their sweet potatoes from the US, the relevant popular types are: California, Beauregard and Georgia Jets. Strange to note that I don’t see any of these varieties here, rather Garnet or Jewel seem to be the common types available. But according to the the CBI, Georgia Jets and the American Covington are highest in demand in Northern Europe, so maybe I was eating one of those and the difference is simply in the varietal itself.

REGULAR TUBER VS. SWEET POTATO VS. YAM

It turns out that the sweet potato is part of the morning glory family and the regular potato is part of the nightshade family, so they’re only distantly related. Furthermore, yams are also a completely different species as they are part of the monocot family, which are related to grasses and lilies. While yams and sweet potatoes sometimes taste similar in sweetness, their origins, size variation and climate needs still vary.

Temperature plays a big role too: the sweet potato is actually a hot summer crop, growing best when daytime temperatures range from 75 to 95 degrees Fahrenheit (so more of a tropical climate) whereas the regular potato is more of a winter crop, preferring temperatures between 50 and 70 degrees Fahrenheit. This means Germany is not currently an ideal place to grow sweet potatoes, so the ones I was eating in Berlin were most likely imported, but from where?

GLOBAL POTATO

I’m going to try to narrow this down as best I can. America is the number one supplier of sweet potatoes in Europe. Although they’re grown in many states, the biggest production comes from North Carolina (unlike Washington and Idaho for the regular potato). Within Europe, the UK and the Netherlands are the top American suppliers, while Portugal followed by Spain, Italy and Greece the top European producers. It seems that as the demand increases (and climate changes permit), Northern Europe is slowly starting to cultivate them too.

It seems there are 3 options: France and Germany are either buying locally from very small sweet potato farmers, importing American from the Netherlands, or buying produce directly from Portugal. It should be said that the sweet potato specifically is NOT very popular in Europe, compared to practically anywhere else in the world; from China to Nigeria, Indonesia to Vietnam, India to Tanzania. While they’re gaining popularity through health consciousness and curiosity, it was actually pretty random of me to eat sweet potato in Europe. I think it had to do with the fact that we were in lockdown and I was doing a lot of home cooking, so I bought a mix of traditional, local produce and things that were familiar to me.

On a side note, here’s a very cool current map of the top potato varieties and where they’re grown around the world. I just wish someone would further add all the varieties and all the locations to see if and where the sweet potato is grown in say, France or Germany on a smaller scale.

US ORGANIC VS. EU ORGANIC

If the sweet tubers in Europe are American, why do they taste different on either side of the ocean? If we go with the theory I was eating European grown potatoes, then according to the international scientific journal PLOS ONE, “apart from the chemical and physical parameters of soil, different field sites differ in the composition of the soil microbiota, which is the main reservoir of microorganisms colonizing plants. This raises the question of to what extent do the microorganisms that colonize potato tubers have an impact on the sprouting behavior of the potato tubers?” If you really want to get into that, you can read the whole article The Bacterial Community in Potato is Recruited from Soil and Partly Inherited Across Generations. Basically, even if the same strain tuber is planted in another place with similar soil composition, weather patterns and care, the native microorganisms will still have an impact on the potato’s character. This is also true for grape vines, humans… any organic matter, really. It makes sense.

Another important thing to consider is what organic really means and to whom. This is relevant whether the potatoes in Europe were imported or produced locally. The US FDA regulations vs EU approved organic legislation have some overlap, but there are a ton of discrepancies between both continents and countries. For example, pesticide residues are one of the crucial issues for fruit and vegetable suppliers. To avoid health and environmental damage, the European Union has set what they call Maximum Residue Levels (MRLs) for pesticides in and on food products. Products that have more pesticides than the maximum allowed are withdrawn or rejected from the European market. What’s more, buyers in several EU Member States, such as the United Kingdom, Germany, The Netherlands and Austria, use MRLs which are stricter than the MRLs laid down in the general European legislation. Supposedly within that, supermarket chains are the strictest and manage 33-70% of the legal MRL. But smaller organic markets and chains, such as the German Bio Company or Sir Plus where I frequently got produce, may not have such a thorough regulation process, but purchase direct from smaller producers who practice minimal intervention farming. It’s a mess to figure out.

Most likely, I was eating either imported American, French or Portuguese sweet potatoes, bought from organic or local markets. But to keep this as straightforward as possible, we could assume it was American all along, in France, Germany and NY. What if they were all from North Carolina, too? Given there is an annual International Sweet Potato Week hosted by the North Carolina Sweet Potato Commission (NCSPC) in several Northern European Countries including Germany, it’s especially plausible. Could it also be that they would taste better overseas, and if so, why?

PRESERVATION OF POTATO

I read that the US only consumes 1/3 of their annual production and freezes the rest. It seems that the EU is more strict about buying seasonal produce, and although the organic sweet potato is still considered to be a niche market, the demand is increasing and so is supplier competition, which means that the US may not always be the lead exporter to the EU. Southern France’s Fruits Union is developing the Beauregard with the intention to slowly take over all imports, offering a “zero residue” potato to France and beyond.

Is it possible that the quality of the exported tuber is higher than the one bought at Whole Foods or Trader Joe’s? If the residue requirements are stricter at Bio Company in Kreuzberg than Whole Foods on E. Houston, maybe the delicate skins do not absorb as many toxins and leave the flesh in a happier, fuller life state, even transported in containers over the ocean. There is nothing inherently better in Portuguese loam soils than North Carolina’s; in fact at one point they were all connected as the same super continent, Pangea.

But when I consider how many food and health products are unavailable in the US, the reason is almost always because they don’t fit regulation requirements for MORE preservatives, not less. This distinction has a huge impact not only on our produce but our minds and lives, maybe in more subtle ways than we realize, but they accumulate nonetheless. We’re way overdue to reexamine why exactly we infuse everything with a cocktail of fillers and additives. Is it an embedded psycho-societal need for control? Can we let it go? Maybe the microbes, the local and naturally occurring ones, are not as scary as we imagine them to be. Maybe they do the job of preserving just fine, as they have since forever, long before we came into existence as a species.

Postnote

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