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The potato

Introducing our special guest,Solanum tuberosum, the “humble tuber”

that spread from its Andean birthplace across six continents, staving off hunger,

fuelling economic developmentand changing the course of world history

12 International Yearof the Potato 2008New light on a hiddentreasure

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flowers

fruit

compound leaf

lateral stem

main stems

stolons

tuber

mother tuber

roots

The tuber

As the potato plant grows, its compoundleaves manufacture starch that is transferredto the ends of its underground stems (orstolons). The stems thicken to form a few oras many as 20 tubers close to the soil surface.The number of tubers that actually reachmaturity depends on available moisture andsoil nutrients. Tubers may vary in shape andsize, and normally weigh up to 300 g each.

At the end of the growing season, theplant’s leaves and stems die down to the soillevel and its new tubers detach from theirstolons. The tubers then serve as a nutrientstore that allows the plant to survive the cold,and later regrow and reproduce. Each tuberhas from two to as many as 10 buds (or“eyes”), arranged in a spiral pattern aroundits surface. The buds generate shoots whichgrow into new plants when conditions becomefavourable once more.

A raw potato tuber is rich in micro-nutrients – the vitamins and minerals that

The plant

The potato (Solanum tuberosum) is aherbaceous annual that grows up to 100 cm tall and produces a tuber – also calledpotato – so rich in starch that it ranks as theworld’s fourth most important food crop, aftermaize, wheat and rice. The potato belongs tothe Solanaceae – or “nightshade”– family offlowering plants, and shares the genusSolanum with at least 1000 other species,including tomato and eggplant. Recentresearch indicates that S. tuberosum isdivided into two, only slightly different,cultivar groups: Andigenum, which is adaptedto short day conditions and is mainly grownin the Andes, and Chilotanum, the potato nowcultivated around the world. Also known asthe “European” potato, the Chilotanum groupis believed to have developed from Andeancultivars introduced first into Chile and fromthere, during the 19th century, into Europe.

Chemical composition of the potato tuber

water 72-75% starch 16-20%

protein 2-2.5%

fibre 1-1.8%

fatty acids 0.15%

14 International Yearof the Potato 2008New light on a hiddentreasure are essential to health. A medium-size potato

contains high levels of potassium and nearlyhalf the daily adult requirement of vitamin C.It is also a good source of B vitamins,and minerals such as phosphorusand magnesium.

Andean heritage

The story of the potato begins about 8 000 years ago near Lake Titicaca, which sitsat 3 800 m above sea level in the Andesmountain range of South America, on theborder between Bolivia and Peru. There,research indicates, communities of huntersand gatherers who had first entered the SouthAmerican continent at least 7 000 yearsbefore, began domesticating wild potatoplants that grew around the lake inabundance.

Some 200 species of wild potatoes arefound in the Americas. But it was in theCentral Andes that farmers succeeded inselecting and improving the first of what wasto become, over the following millennia, astaggering range of tuber crops. In fact, whatwe know as “the potato” (Solanum speciestuberosum) contains just a fragment of thegenetic diversity found in the four recognizedpotato species and 5 000 potato varieties stillgrown in the Andes.

Although Andean farmers cultivated manyfood crops – including tomatoes, beans andmaize – their potato varieties provedparticularly suited to the quechua or “valley”zone, which extends at altitudes of from 3 100to 3 500 m along the slopes of the CentralAndes (among Andean peoples, the quechuawas known as the zone of “civilization”). Butfarmers also developed a frost-resistant potatospecies that survives on the alpine tundra ofthe puna zone at 4 300 m.

The food security provided by maize andpotato – consolidated by the development of

Micronutrients(one raw potato, including skin, 213 g)Minerals

potassium 897 mgphosphorus 121 mgmagnesium 49 mgiron 1.66 mg

Vitamins

vitamin C 42 mgniacin 2.2 mgvitamin B6 0.62 mgthiamine 0.17 mg

Source: United States National Nutrient Database

irrigation and terracing – allowed for theemergence around 500 AD of the Huaricivilization in the highland Ayacucho basin.Around the same time, the city state ofTiahuanacu rose near Lake Titicaca, thankslargely to its sophisticated “raised field”technology – elevated soil beds lined withwater canals – which produced potato yieldsestimated at 10 tonnes perhectare . At its height, around800 AD, Tiahuanacu andneighbouring valleys arebelieved to have sustained apopulation of 500 000 or more.

Meteoric rise. The collapse ofHuari and Tiahuanacu between1000 and 1200 led to a period ofturmoil that ended with themeteoric rise of the Incas in theCusco valley around 1400. Inless than 100 years, they createdthe largest state in pre-Columbian America, extendingfrom present-day Argentinato Colombia.

The Incas adopted andimproved the agriculturaladvances of previous highlandcultures, and gave special

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The dawn of agricultureIncan myths relate that the Creator, Viracocha, causedthe sun, moon and stars to emerge from Lake Titicaca.He also created agriculture when he sent his two sonsto the human realm to study and classify the plants thatgrew there. They taught the people to sow cropsand how to use them so that they would never lack food.

Lake Titicaca,a centre of Andeancivilization

importance to maize production. But thepotato was fundamental to the food security oftheir empire: in the Incas’ vast network ofstate storehouses, potato – especially a freeze-dried potato product called chuño – was oneof the main food items, used to feed officials,soldiers and corvée labourers, and as anemergency stock after crop failures.

The Spanish invasion, in 1532, brought anend to the Incas – but not to the cultivation ofpotatoes. For, throughout Andean history, thepotato – in all its forms – was profoundly a“people’s food”, playing a central role theAndean vision of the world (time, forexample, was measured by how long it took tocook a pot of potatoes).

Farmers in some parts ofthe high Andes still measureland in topo, the area a familyneeds to grow their potatosupply – a topo is larger athigher altitudes, where plotsneed to lie fallow for longer.They classify potatoes not onlyby species and variety, but bythe ecological niche where thetubers grow best, and it is notunusual to find four speciescultivated on a single, smallplot of land.

Planting tubers remainsthe most important activityof the farming year near LakeTiticaca, where the potatois known as Mama Jatha,or mother of growth. Thepotato remains the seedof Andean society.

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“The potato eaters” (1885) by Vincent Van Gogh

potato was poisonous. At the same time,however, Europe’s “Age of Discovery” hadbegun, and among the first to appreciatepotatoes as food were sailors who took tubersto consume on ocean voyages. That is how thepotato reached India, China and Japan earlyin the 17th century.

The potato also received an unusuallywarm welcome in Ireland, where it provedsuited to the cool air and moist soils. Irishimmigrants took the tuber – and the name,“Irish potato” – to North America in theearly 1700s.

Long summer days. The widespread adoptionof the potato as a food crop in the northernhemisphere was delayed not only byentrenched eating habits, but by the challengeof adapting a plant grown for millennia in theAndes to the temperate climate of the north.Only a drop of the rich potato gene pool hadleft South America, and it took 150 yearsbefore varieties suited to long summer daysbegan to appear.

Those varieties arrived at a crucial time. Inthe 1770s, much of continental Europe wasdevastated by famines, and the potato’s valueas a food security crop was suddenlyrecognized. Frederick the Great of Prussiaordered his subjects to grow potatoes as

Diffusion

The diffusion of the potato from the Andes tothe rest of the globe reads like an adventurestory, but it began with a tragedy. The Spanishconquest of Peru between 1532 and 1572destroyed the Inca civilization and caused thedeaths – from war, disease and despair – of atleast half the population.

The conquistadores came in search ofgold, but the real treasure they took back toEurope was Solanum tuberosum. The firstevidence of potato growing in Europe datesfrom 1565, on Spain’s Canary Islands. By1573, the potato was known to be cultivatedon the Spanish mainland. Soon after, tuberswere being sent around Europe as exotic gifts– from the Spanish court to the Pope inRome; from Rome to the papal ambassador inMons; and from there to a botanist in Vienna.Potatoes were grown in London in 1597and reached France and the Netherlandssoon after.

But once the plant had been added tobotanical gardens and herbalists’encyclopaedias, interest waned. Europeanaristocracy admired its flowers, but the tuberswere considered fit only for pigs and thedestitute. Superstitious peasants believed the


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“Potato famine”. But the potato’s successproved a double-edged sword. For the tubersthat were being cloned and cultivated acrossNorth America and Europe belonged to a few,genetically similar varieties. That meantthey were highly vulnerable: a pest or diseasethat struck one plant could spread quicklyto the rest.

The first sign of impending disaster camein 1844-1845, when a mould disease, lateblight, ravaged potato fields acrosscontinental Europe, from Belgium to Russia.But the worst came to Ireland, where potatosupplied 80 percent of calorie intake. Between1845 and 1848, late blight destroyed threepotato crops, leading to famines that causedthe deaths of one million people.

The Irish catastrophe led to concertedefforts to develop more productive anddisease-resistant varieties. Breeders in Europeand North America, drawing on new potatogermplasm from Chile, produced many of themodern varieties that laid the foundation formassive potato production in both regions formost of the 20th century.

Meanwhile, European colonialism andemigration were taking the potato to allcorners of the globe. Colonial governors,missionaries and settlers introduced potatogrowing to the floodplains of Bengal andEgypt’s Nile delta, the Atlas Mountains ofMorocco, and the Jos plateau in Nigeria.Emigrant farmers took the potato to Australiaand even to South America, establishing thepotato in Argentina and Brazil.

In the Asian heartland, the tuber movedalong more ancient routes, finding its wayfrom the Caucasus to Turkey’s Anatolian

insurance against cereal crop failure, while theFrench scientist Parmentier succeeded inhaving the potato declared “edible” (aroundthe same time, on the other side of the Atlantic,the President of the United States, ThomasJefferson, served French fries to White Houseguests).

After initial hesitation, European farmers –even those in Russia, where the potato wascalled the “devil’s apple” – began growingpotatoes on a large scale. The potato becameEurope’s food reserve during the Napoleonicwars, and by 1815 it had become a staple cropacross northern Europe. By then, the IndustrialRevolution was transforming agrarian societyin the United Kingdom, displacing millions ofrural people into crowded cities. In the newurban environment, the potato became the firstmodern “convenience food” – energy-rich,nutritious, easy to grow on small plots, cheap topurchase, and ready to cook without expensiveprocessing.

Increased potato consumption during the19th century is credited with helping to reducethe scourge of diseases such as scurvy andmeasles, contributing to higher birth rates andthe population explosion in Europe, the UnitedStates and the British Empire.

Papa, patata, potato...While the Incas called it papa (as do modern-day Latin Americans), the Spaniards calledthe potato patata, apparently confusing itwith another New World crop, the sweetpotato (known as batata). In 1797, theEnglish herbalist Gerard referred to the sweetpotato as “common potatoes”, and for manyyears S. tuberosum was known as the “Virginiapotato” or “Irish potato” before finallydisplacing batata as the potato.

highlands of Cameroon, Kenya, Malawi and Rwanda.

The potato has an extraordinarily richpast, and a bright future. While production inEurope – the potato’s “second home” for fourcenturies – is declining, the potato has ampleroom for expansion in the developing world,where its consumption is less than a quarterthat of developed countries.

Today in mountainous Lesotho, manyfarmers are shifting from maize to potato,assisted by an FAO project for production ofvirus-free seed tubers. In China, agricultureexperts claim that a staggering 30 percentincrease in potato yields is within reach.

And in the Andes, where it all began, theGovernment of Peru created in July 2008 anational register of Peruvian native potatovarieties, to help conserve the country’s richpotato heritage. That genetic diversity, thebuilding blocks of new varieties adapted to theworld’s evolving needs, will help write futurechapters in the story of Solanum tuberosum.

plateau, from Russia to western China, andfrom China to the Korean Peninsula. In themountain valleys of Tajikistan, some potatotypes have been grown long enough to beconsidered “old local varieties”.

The 20th century saw the potato finallyemerge as a truly global food. The SovietUnion’s annual potato harvest reached 100 million tonnes. In the years following the Second World War, huge areas of arableland in Germany and Britain were dedicatedthe potato, and countries like Belarus andPoland produced – and still do – morepotatoes than cereals.

The potato came into its own as a snackfood. The invention in the 1920s of themechanical potato peeler helped make potatocrisps America’s top-selling snack. Arestaurant chain founded by the McDonaldbrothers in the United States in 1957 spentmillions of dollars to “perfect the French fry”.A Canadian firm, McCain, that began makingfrozen French fries in 1957, expanded to open57 production facilities on six continents andnow supplies one third of all French friedpotatoes produced internationally.

Exploding demand. From the 1960s,cultivation of the potato began to expand inthe developing world. In India and Chinaalone, total production rose from 16 milliontonnes in 1960 to almost 100 million in 2007.In Bangladesh, potato has become a valuablewinter cash crop, while potato farmers inSoutheast Asia have tapped into explodingdemand from food industries. In sub-SaharanAfrica, potato is a preferred food in manyurban areas, and an important crop in the


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However, it is also vulnerable to a number of pests and diseases. To prevent the build-upof pathogens in the soil, farmers avoidgrowing potatoes on the same land from yearto year. Instead, they grow potatoes inrotations of three or more years, alternatingwith other, dissimilar crops, such as maize,beans and alfalfa. Crops susceptible to thesame pathogens as the potato (e.g. tomato)are avoided, in order to break thedevelopment cycle of potato pests.

With good agricultural practices, includingirrigation when necessary, a hectare of potatoin the temperate climates of northern Europeand North America can yield more than 40 tonnes of fresh tubers within four months

of planting. In mostdeveloping countries, however,average yields are much lower– ranging from as little as 5 to 25 tonnes – owing to lackof high quality seed andimproved cultivars, lower ratesof fertilizer use and irrigation,and pest and disease problems.

Cultivation

Potato is grown in more than 100 countries,under temperate, subtropical and tropicalconditions. It is essentially a “cool weathercrop”, with temperature being the mainlimiting factor to production: tuber growth issharply inhibited in temperatures below 10°Cand above 30°C , while optimum yields areobtained where mean daily temperatures arein the 18 to 20°C range.

For that reason, potato is planted in earlyspring in temperate zones and late winter in warmer regions, and grown during thecoolest months of the year in hot tropicalclimates. In some sub-tropical highlands,mild temperatures and high solar radiationallow farmers to grow potatoes throughout the year, and to harvest tubers within 90 daysof planting (in temperate climates, such as in northern Europe, that can take up to 150 days).

The potato is a very accommodating andadaptable plant, and will produce well evenwithout ideal soil and growing conditions.

Potato fieldsin central Java,Indonesia

Selecting seed potatoSeed potato is usually the mostexpensive input to potatocultivation, accountingfor from 30 to50 percent ofproduction costs.In areas ofdeveloping countries where noformal seed supply system exists,farmers have devised their ownad hoc method for selecting seedtubers: they sell the largestpotatoes for cash, eat the medium-sized ones at home, and keep thesmallest as future plantingmaterial.

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to farmers’ own seed, but expected profitsmust offset the higher cost.

The planting density of a row of potatoesdepends on the size of the tubers chosen, whilethe inter-row spacing must allow for ridgingof the crop (see below). Usually, about twotonnes of seed potatoes are sown per hectare. For rainfed production in dryareas, planting on flat soil gives higher yields (thanks to better soil waterconservation), while irrigated crops aremainly grown on ridges.

Crop careDuring the development of the potato canopy,which takes about four weeks, weeds must becontrolled in order to give the crop a“competitive advantage”. If the weeds arelarge, they must be removed before ridgingoperations begin. Ridging (or “earthing up”)consists of mounding the soil from betweenthe rows around the main stem of the potatoplant. Ridging keeps the plants upright andthe soil loose, prevents insect pests such as thetuber moth from reaching the tubers, andhelps prevent the growth of weeds.

After earthing up, weeds between the

Soil and land preparationThe potato can be grown on almost any typeof soil, except saline and alkaline. Naturallyloose soils, which offer the least resistance toenlargement of the tubers, are preferred, andloamy and sandy loam soils that are rich inorganic matter, with good drainage andaeration, are the most suitable. Soil with a pHrange of 5.2 – 6.4 is considered ideal.

Growing potatoes involves extensiveground preparation. The soil needs to beharrowed until completely free of weed roots.In most cases, three ploughings, along withfrequent harrowing and rolling, are neededbefore the soil reaches a suitable condition:soft, well-drained and well-aerated.

PlantingThe potato crop is usually grown not fromseed but from “seed potatoes” – small tubersor pieces of tuber sown to a depth of 5 to 10 cm. Purity of the cultivars and healthy seed tubers are essential for a successful crop. Tuber seed should be disease-free, well-sprouted and from 30 to 40 g in weight.Use of good quality commercial seed canincrease yields by 30 to 50 percent, compared


1. Planted seed tuber 2. Vegetative growth 3. Tuber initiation 4. Tuber bulking

Stages in crop development

Potato varietiesAlthough the potato cultivated worldwide belongs to just one botanical species, Solanum tuberosum, the tubers come in thousands of varieties with great differencesin size, shape, colour, texture, cooking characteristics and taste.Here is a small sample of potato diversity:

1. Atahualpa

Bred in Peru, a highyielding variety goodfor both baking andfrying

2. Nicola

Widely grown Dutchvariety, one of the bestfor boiling, also good insalads

3. Russet Burbank

The classic Americanpotato, excellent forbaking and French fries

4. Lapin puikula

Grown in Finland forcenturies, in fieldsbathed in the light ofthe midnight sun

5. Yukon Gold

A Canadian potato withbuttery yellow fleshsuitable for frying,boiling, mashing

growing plants and at the top of the ridge areremoved mechanically or by using herbicides.Ridging should be done two or three times atan interval of 15 to 20 days. The first shouldbe done when the plants are about 15-25 cmhigh; the second is often done to cover thegrowing tubers.

Manuring and fertilizationThe use of chemical fertilizer depends on thelevel of available soil nutrients – volcanicsoils, for example, are typically deficient inphosphorus – and in irrigated commercialproduction, fertilizer requirements arerelatively high. However, the potato canbenefit from application of organic manure at

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6. Tubira

CIP-bred variety grownin West Africa. Whiteflesh, pink skin

7. Vitelotte

A gourmet Frenchvariety prized for itsdeep blue skin andviolet flesh

8. Royal Jersey

From the Isle of Jersey:the only Britishvegetable with an EUdesignation-of-origin

9. Kipfler

Hails from Germany.Elongated with creamflesh, popular in salads

10. Papa colorada

Brought to the CanaryIslands by passingSpanish ships in 1567

11. Maris Bard

Bred in the UnitedKingdom, a whitevariety with a soft waxytexture good for boiling

12. Désirée

Red-skinned, withyellow flesh and adistinctive flavour

13. Spunta

Another popularcommercial tuber, goodfor boiling and roasting

14. Mondial

A Dutch potato withsmooth good looks.Boils and mashes well

15. Unknown

One of more than 5 000native varieties stillgrown in the Andes

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22 International Yearof the Potato 2008New light on a hiddentreasure the start of a new rotation: it provides a good

nutrient balance and protects the structure ofthe soil. Crop fertilization requirements needto be correctly estimated according to theexpected yield, the potential of the variety andthe intended use of the harvested crop.

Water supplyThe soil moisture content must be maintainedat a relatively high level. For best yields, a 120to 150 day crop requires from 500 to 700 mmof water. In general, water deficits in themiddle to late part of the growing period tendto reduce yield more than those in the earlypart. Where supply is limited, water should bedirected towards maximizing yield per hectarerather than being applied over a larger area.

Because the potato has a shallow rootsystem, yield response to frequent irrigation is considerable, and very high yields areobtained with mechanized sprinkler systemsthat replenish evapotranspiration losses everyone or two days. Under irrigation in temperateand subtropical climates, a crop of about 120 days can produce yields of 25 to 35 tonnes/ha , falling to 15 to 25 tonnes/hain tropical areas.

Pests and diseasesA few basic precautions against diseases –crop rotation, using tolerant varieties andhealthy, certified seed tubers – can help avoidgreat losses. There is no chemical control forbacterial and viral diseases but they can becontrolled by regular monitoring (and whennecessary, spraying) of their aphid vectors.The severity of fungal diseases such as lateblight depends, after the first infection, mainlyon the weather – persistence of favourableconditions, without chemical spraying, canquickly spread the disease.

Insect pests can wreak havoc in a potatopatch. Recommended control measuresinclude regular monitoring and steps toprotect the pests’ natural enemies. Evendamage caused by the Colorado potato beetle,a major pest, can be reduced by destroyingbeetles, eggs and larvae that appear early inthe season, while sanitation, crop rotationsand use of resistant potato varieties helpprevent the spread of nematodes.

HarvestingYellowing of the potato plant’s leaves and easyseparation of the tubers from their stolonsindicate that the crop has reached maturity. If the potatoes are to be stored rather thanconsumed immediately, they are left in the soil to allow their skins to thicken – thickskins prevent storage diseases and shrinkagedue to water loss. However, leaving tubers for too long in the ground increases theirexposure to a fungal incrustation called black scurf.

To facilitate harvesting, the potato vinesshould be removed two weeks before the

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potatoes are dug up. Depending on the scaleof production, potatoes are harvested using aspading fork, a plough or commercial potatoharvesters that unearth the plant and shakeor blow the soil from the tubers. Duringharvesting, it is important to avoid bruising orother injury, which provide entry points forstorage diseases.

StorageSince the newly harvested tubers are living tissue – and therefore subject todeterioration – proper storage is essential,both to prevent post-harvest losses of potatoesdestined for fresh consumption or processing,and to guarantee an adequate supply of seedtubers for the next cropping season.

For ware and processing potatoes, storageaims at preventing “greening” (the build upof chlorophyll beneath the peel, which isassociated with solanine, a potentially toxicalkaloid) and losses in weight and quality.The tubers should be kept at a temperature of6 to 8°C degrees, in a dark, well-ventilatedenvironment with high relative humidity (85to 90 percent). Seed tubers are stored, instead,under diffused light in order to maintain theirgermination capacity and encouragedevelopment of vigorous sprouts. In regions,such as northern Europe, with only onecropping season and where storage of tubersfrom one season to the next is difficultwithout the use of costly refrigeration, off-season planting may offer a solution.

Uses of potato

Once harvested, potatoes are used for a varietyof purposes, and not only as a vegetable forcooking at home. In fact, it is likely that lessthan 50 percent of potatoes grown worldwideare consumed fresh. The rest are processedinto potato food products and foodingredients, fed to cattle, pigs and chickens,processed into starch for industry, and re-usedas seed tubers for growing the next season’spotato crop.

Food uses: fresh, “frozen”,dehydratedFAO estimates that just over two-thirdsof the 320 million tonnes of potatoesproduced in 2005 were consumed by peopleas food, in one form or another. Home-grownor purchased in markets, fresh potatoes

are baked, boiled or fried and usedin an astonishing range of recipes:mashed potatoes, potato pancakes, potatodumplings, twice-baked potatoes, potato soup,potato salad and potatoes au gratin,to name a few.

However, the global consumption of potatoas food is shifting from fresh potatoes toadded-value, processed food products.

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Potatoes awaiting salein La Plata, Argentina

24 International Yearof the Potato 2008New light on a hiddentreasure One of the main items in that category goes

by the unappetizing name of frozen potatoes,but includes most of the French fries (“chips”in the United Kingdom) served in restaurantsand fast food chains worldwide. Theproduction process is fairly simple: peeledpotatoes are shot through cutting blades,parboiled, air dried, par fried, frozen andpackaged. The world’s appetite for factory-made French fries is estimated at more than11 million tonnes a year.

Another processed product, the potato crisp(“chips” in the United States), is the long-standing king of snack foods in manydeveloped countries. Made from thin slices ofdeep-fried or baked potato, they come in avariety of flavours – from simple salted to“gourmet” varieties tasting of roast beef andThai chili. Some crisps are produced using adough made from dehydrated potato flakes.

Dehydrated potato flakes and granulesare made by drying a mash of cooked potatoesto a moisture level of 5 to 8 percent. Flakes areused in retail mashed potato products, asingredients in snacks, and even as food aid: as part of its international food assistance, the United States has distributed potato flakesto more than 600 000 people. Anotherdehydrated product, potato flour, is groundfrom cooked, whole potatoes and retains adistinct potato taste. Gluten-free and rich instarch, potato flour is used by the foodindustry to bind meat mixtures and thickengravies and soups.

Modern starch processing can retrieve asmuch as 96 per cent of the starch found inraw potatoes. A fine, tasteless powder with“excellent mouth-feel”, potato starch provides

higher viscosity than wheat and maizestarches, and delivers a more tasty product. Itis used as a thickener for sauces and stews,and as a binding agent in cake mixes, dough,biscuits and ice-cream.

Finally, in eastern Europe andScandinavia, crushed potatoes are heated toconvert their starch to fermentable sugars thatare used in the distillation of alcoholicbeverages such as vodka and akvavit.

Non-food uses: Glue, animal feedand fuel-grade ethanolPotato starch is also widely used by the

pharmaceutical, textile,wood and paper industriesas an adhesive, binder,texture agent and filler, andby oil drilling firms to washboreholes. Potato starch is a100% biodegradablesubstitute for polystyrene

and other plastics and used, for example, indisposable plates, dishes and knives.

Potato peel and other “zero value” wastesfrom potato processing are rich in starch thatcan be liquefied and fermented to producefuel-grade ethanol. A study in Canada’spotato-growing province of New Brunswickestimated that 440 000 tonnes of processingwaste could produce 4 to 5 million litres ofethanol.

One of the first widespread uses of thepotato in Europe was as farm animal feed. Inthe Russian Federation and other EastEuropean countries, as much as half of thepotato harvest is still used for that purpose.Cattle can be fed up to 20 kg of raw potatoes

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a day, while pigs fatten quickly on a daily dietof 6 kg of boiled potatoes. Chopped up andadded to silage, the tubers cook in the heat offermentation.

Seed potatoes: renewing the cycle...Unlike other major field crops, potatoes are

reproducedvegetatively, fromother potatoes.Therefore, a part ofeach year’s crop – ranging from 5 to

15 percent, depending on the quality of theharvested tubers – is set aside for re-use in thenext planting season. Most farmers indeveloping countries select and store theirown seed tubers. In developed countries,farmers are more likely to purchase disease-free “certified seed” from dedicated suppliers.More than 13 percent of France’s potatogrowing area is used to produce seed potatoes,and the Netherlands exports some 700 000tonnes of certified seed a year.

Potatoesin the kitchen

What has made the “humble tuber” theworld’s No. 4 food crop is not only itsnutritional value but its amazing versatility inthe kitchen. Potatoes are the world’s mostpopular vegetable, and have been welcomedinto the cuisines of countries around theglobe. Potatoes are used in curries in Indiaand in pasta in Italy, stewed with bananas inCosta Rica, baked with rice in Iran, stuffedwith liver in Belarus, stir-fried with greenbeans in Ethiopia, and simmered withsmoked haddock in winter soups in Finland.

The secret of the potato’s success is its greatdiversity: in Peru, a potato salad may includethree or four different types. While the choiceof tubers is more limited elsewhere, modernvarieties of Solanum tuberosum offer a widerange of cooking characteristics suitable forhundreds of different dishes. Some give soupsa creamy density, providing a delicate tastethat highlights other ingredients. Otherpotatoes are great when baked, served as asimple snack or with a filling as a completemeal. Roast potatoes – crisp and goldenoutside and fluffy inside – are the perfect

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Traditional dishof the CanaryIslands

accompaniment to roast meat. Smooth,creamy, mashed potato is said to be the“ultimate comfort food”, while “new”potatoes, steamed or boiled, are considered aspecial delicacy.

Most potato recipes are easy to prepare. Butchoosing the right potato variety is essentialfor a successful potato dish – in the kitchen,potatoes are classified according to theirstarch content, which determines how theyreact to cooking. Basically, the more starchthey contain, the more easily the tuber’sstarch cells burst when heated.

Choosing the “right potato”High-starch potatoes, also called “floury”potatoes, generally have coarse, corky skin

and a dry texture (due to lowerlevels of moisture). Boiled, theytend to fall apart. But they areunbeatable for baking, makingFrench fries, and yielding light,

fluffy mashed potato. Common high-starchvarieties are Russets, Bintje, King Edwardand Maris Piper.

Medium-starch (or “allpurpose”) potatoes includelong white, round white andyellow potatoes, such as YukonGold, German Butterball andNicola, as well as purple-

fleshed tubers. They are more moist thanbaking potatoes, but – some say – have ablander taste. Ideal for steaming, they go wellin stews and in baked, roasted, pan-fried and au gratin dishes.

Low-starch potatoes are called “waxy”for their glossy skins. These moist tubers keep

their shape during cooking,making them the best choicefor boiling, sautés, stews andsalads (in France, waxyvarieties are preferred for

making thick mashed potato). Use fingerlingand round reds, or “new” (immature, of anyvariety) potatoes.

Factsheets. To deepen understandingof the potato’s role in world agriculture,

the economy and global food security,FAO specialists compiled a series

of factsheets on key issuesin potato development.


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