Potatoes

The only edible part of the potato plant is the tuber, the swollen underground portion of the of the stem we know as the potato.  The rest of the this member of the nightshade family is poisonous.  Tubers act as food storage for the plant and and are highly productive compared to grains.  If the head of a wheat or rice plant grows too big, the plant will fall over, with fatal results. Growing underground, tubers are not limited by the rest of the plant. World record potatoes have grown to 25 pounds.

History

Potatoes are native to South America, having first been cultivated in Peru some 7000 years ago.  The Incas preserved the potato by dehydrating and mashing the potatoes.  The dried potato pulp was stored for up to 10 years.  Potatoes arrived in Europe in the 16th century after the Spanish conquest of the Incan Empire (1532-1570).    But in early modern Europe, the potato was a startling novelty, frightening to some, bewildering to others.  Some believed it an aphrodisiac, others a cause of fever and the fruit of the devil.  Coming from the strange New World, it was feared to cause leprosy because it resembled a leper’s deformed fingers and toes.   It would take nearly two hundred more years before the potato would reach acceptance throughout Europe.  

In 1744, Prussian King Frederick the Great, saved his people from a famine by ordering them eat potatoes.  Antoine-Augustin Parmentier, a French pharmacist introduced the potato to France. During multiple prison stints at the hands of the Prussians during the Seven Years’ War,  he was fed little but potatoes. He was surprised that the meager rations of potatoes kept him in such good health. He devoted the rest of his life to promoting the potato.  

He promoted the potato tirelessly; presenting an all-potato dinner to high-society guests (the story goes that Thomas Jefferson, one of the guests, was so delighted he introduced French fries to America); supposedly persuaded the king and queen to wear potato blossoms; and famously planted 40 acres of potatoes at the edge of Paris  He let it be known that this was the king’s garden, knowing that famished commoners would steal them eagerly.

By the end of the 18th century,  potatoes had become a staple in Europe.  Between 1845 and 1852 a million or more Irish people died in one of the deadliest famines in history.  At the time, nearly 40% of the population of Ireland ate no other solid food except the potato.  A mold destroyed most of the potato crop killing  1/2 the population and forcing two-million to leave Ireland.  About 75% of those fleeing the famine immigrated to the United States.

Types of Potatoes

Like rice, potatoes are categorized by the type and amount of starch they have.  Potatoes with an abundance of amylopectin, are referred to as low starch or “waxy.”  Potatoes with amylose as their predominant starch are referred to as high starch or “mealy”.

High-starch potatoes have a light, mealy texture and are preferred for baking, mashing, and french-frying.  The cells of a high-starch potato separate when cooked producing fluffy baked potatoes and mashed potatoes that readily soak up milk and butter and hold plenty of air when whipped. But highstarch potatoes also absorb water, so they fall apart when boiled.  Russets or Idahos are the principal varieties.

Medium-starch potatoes are called all-purpose or chef potatoes. They’re moister than high-starch potatoes and hold their shape a bit better.  These potatoes are suitable for most applications except baking.  Varieties include Yukon Gold.

Low-starch potatoes or waxy potatoes, have a more cohesive cell structure and hold their shape better than other types of potato making them preferred for dishes like potato salads, soups, and hash browns.   They are high in moisture and higher in sugar.  Their higher sugar content make them unsuitable for frying.  Different varieties of waxy potatoes vary in their moisture content as do potatoes of differing growing and storage conditions.  Varieties include white, yellow, and red-skinned potatoes, and fingerling potatoes.

New Potatoes, are potatoes that are picked before they are mature.  Their skin is tender and thin and their starch content is lower.

Storing Potatoes

Store potatoes in a cool, dark, dry, well-ventilated place.  Think root cellar.  Don’t refrigerate raw potatoes, some of their starches convert to sugar.  Don’t expose potatoes to sunlight.  The light activates a toxic compound called solanine and turns the potato green and bitter.

Solanine is a toxin found in plants of the nightshade family, such as eggplants, potatoes, tomatoes, and the infamous deadly belladonna.  Leaves, roots, flowers, stems, and fruits can all contain solanine in varying levels.

This toxin has neurological and gastrointestinal effects. When it is ingested in large enough quantities, it can cause nausea, cramps, vomiting, and diarrhea, in addition to symptoms like confusion, dizziness, difficulty walking, and slurred speech. Eventually, the body will become overloaded with the toxin, causing organs to fail and eventually leading to death or severe injury. 

Usually, the solanine levels in things like eggplant, potatoes, and tomatoes are too low to cause health problems. However, there are circumstances in which solanine can be elevated. Unripe tomatoes tend to have higher levels of the toxin, as do potatoes which have been damaged or exposed to the sun, because the plants form more solanine in response to perceived threats. Sprouts of potatoes and tomatoes also have high levels of the toxin.

Avoid unripe tomatoes and potatoes which have started to turn green, as the green color indicates that the potato has been exposed to the sun.  Solanine is heat resistant and isn’t altered or removed by most cooking methods.

Potato Varieties

Fingerling Potatoes 
Fingerling potatoes are small (2-4 inches in length), narrow and elongated like a finger. They are known for their smooth, creamy texture and a rich, nutty flavor.  Fingerlings are low in starch and grow in a variety of colors, including red, purple-pink and yellow. Fingerling potatoes are ideal for roasting, boiling or steaming. 

Purple Potatoes or Purple Peruvian Potatoes
Blue or purple potatoes originated in Peru. The color can become lavender when cooking. The starch level is medium, so purple Peruvians are an all-purpose potato. They are moist and earthy-tasting, sometimes with a nutty flavor; and the color is very dramatic. Purple potatoes also have higher levels of polyphenol antioxidants.

Red Potatoes
Red potatoes, commonly found in supermarkets, have red skin and smooth and waxy white flesh. A firm, smooth and moist potato that holds its shape when cooked.  Red potatoes are best steamed, boiled, roasted or scalloped. They are popularly used in potato salads and gratins.  Red potatoes can be substituted for white in any recipe that requires waxy potatoes.

Russet Potatoes, Idaho Potatoes, or Baking PotatoesRusset Burbank potatoes are the most commonly used potatoes in the U.S. They are grown year-round. With their large, oblong shapes, they are the ideal baking potato. As a floury potato, they are not recommended for making potato salads, because they lose their shape when cooked.  Being high in starch, they are light and fluffy when cooked and the preferred potato for French fries and mashed potatoes.  Their skin is thick and dark brown, low in moisture. It is flavorful and usually left on.

White Potatoes, Chef Potatoes or All-Purpose Potatoes
White potatoes are round to long shape with white or tan skin and white flesh.  They are a medium starch potato, slightly creamy, slightly dense with a thin, delicate skin.   They are preferred for mashed potatoes, salads, steaming/boiling,  or frying.  White potatoes hold their shape well after cooking. Their delicate, thin skins add just the right amount of texture to a velvety mashed potato dish without the need for peeling. Grilling whites brings out a more full-bodied flavor.

Yellow Potatoes
Yellow potatoes, such as Klondike Gold, Milva, Yellow Fin and Yukon Gold, are all purpose potatoes. They are creamy and dense with yellow flesh, ideal for either mashing or baking. They are also great for frying, and are one of the most popular all-purpose potatoes.

New Potatoes
New potatoes are immature potatoes harvested in the spring and early summer. Their skin is thinner and more delicate than mature potatoes. New potatoes are low in starch and high in moisture.  They have a shorter shelf life than mature potatoes and must be used up quickly. 

Sweet Potatoes
Sweet potatoes are yellow or orange elongated tubers with ends that taper to a point and are of two dominant types. The paler-skinned sweet potato has a thin, light yellow skin with pale yellow flesh which is not sweet and has a dry, crumbly texture similar to a white baking potato. The darker-skinned variety has a thicker, dark orange to reddish skin with a vivid orange, sweet flesh and a moist texture.  Sweet potatoes are erroneously referred to as yams.

Yams
The yam is a tuber, not related to the sweet potato, that has a brown or black skin which resembles the bark of a tree and off-white, purple or red flesh, depending on the variety. They are found in tropical climates, primarily in South America, Africa, and the Caribbean. 

Sweet Potato vs. Potato

Sweet Potato vs. Potato

• Calorically, sweet potato and potato are pretty similar. Nutritionally, sweet potato has 50% more fiber, a dramatically higher level of Vitamin A, and more Vitamins C and B6, but less potassium than potato.
• Numbers are only part of the story. Not shown here are the various phytonutrients contained in both sweet potato and potato, which have shown strong antioxidant and anti-inflammatory properties.  The orange hues in sweet potato are due to the super antioxidant beta-carotene, and a unique storage protein called sporamin has been shown to have its own antioxidant properties. There is also a purple-colored variety of sweet potato containing high levels of anthocyanins.  Some potato varieties have been shown to contain phenolic compounds that rival those in broccoli or Brussels sprouts, and some varieties have high levels of Vitamin C and quercetin.

Sizes
Russet potatoes are sized by count, the number of potatoes in a 50-pound box.  120-count would be 114-126 potatoes per box weighing 4 to 8 ounces each.  90-count would be 86-95 potatoes per box weighing 7-12 ounces each.

Other potatoes:

• Jumbo: 3½” diameter potato or larger
• Premium: 2½” to 3½” diameter.
• A-size: 40% or more of potatoes are 2 ½” diameter. Typically used in consumer bags.
• B-size: 1 ½” to 2 ¼” diameter range. Commonly call “new” potatoes or baby reds.
• C-size: Less than 1 ½” in diameter. The smallest potatoes available.

Grades

Discoloration
Potatoes, like apples, begin to turn brown or oxidizes after the peel is removed, due to an enzyme called tyrosinase. When you cut an apple or potato, you open up some of the cells, so that the tyrosinase in them has access to oxygen in the air and starts the enzymatic browning reaction.

To prevent sliced or shredded potatoes from turning brown, cover them with cool water to minimize exposure to air and oxygen.

Adding an acid, such as vinegar or lemon juice, to the water will delay browning even further.

Also, cooking the potatoes as soon as possible after you shred them will give them less time to oxidize. Heat denatures the enzyme, inactivating it.

(Incidentally, tyrosinase also exists in humans, and plays a part in producing melanin, which is what gives our skin and hair their color! Humans who lack tyrosinase are known as albinos.)

If potatoes are turn brown or grey when cooked, it may be they were stored at too cold a temperature. Potatoes should be kept in a cool, dark place, but never stored in the refrigerator.