e.Newsletter
February 2007

Potato Trade-Offs

Consider the lowly potato, the starchy staple of many different world cuisines.  This familiar tuber, fondly labeled la pomme de terre (“apple of the earth”) in France, is the most commonly eaten vegetable in the U.S.  The average American eats 130 pounds of potatoes a year, in many different ways:  boiled, mashed, roasted, steamed, fried or baked. 

Often, someone else does the prep work:  over half of the 20 million metric tons of potatoes grown in the U.S. each year are sold to food processors.  Many of these potatoes get turned into fast food French fries, wind up as frozen “tots” or get dehydrated into mashed potato mixes.  Another 12% of the potatoes sold to processors each year become potato chips. 

And we Americans eat them up:  over $6 billion worth of potato chips are sold in the U.S. each year.  How does the apple of the earth change as it makes its way from the farm to the snack food aisle?   Let’s take a look. 

Note: the figures used in the example below are derived from data provided by the USDA and the food processing industry.  The changes in nutritional content described are typical of the process, but individual potatoes and processing methods vary. 

Harvesting

In its just-picked state, a medium-sized (3 inches in diameter, say) raw potato doesn’t entirely deserve its “nothing but starch” reputation.   There’s about as much protein in there as in a cup of steamed spinach (4 grams), virtually no fat, and nearly 5 grams of fiber, which is about the amount you’d find in two slices of whole wheat bread.  Not to mention almost 900 milligrams of potassium (that’s roughly two banana’s worth), along with substantial amounts of vitamin C, vitamin B6, phosphorus and folate. 

And, of course, there are the carbs:  our medium-sized tater contains about 40 grams of total carbohydrates, the vast majority of which occur in the form of the particular combination of sugar molecules (amylose and amylopectin) popularly known as starch.   

There’s one substance, however, that potatoes contain in even greater amounts:  water.  As much as 80 percent of the weight of our raw potato is plain old H₂0.  

The potato now gets hefted, along with several thousand of its siblings, into a truck to be taken to the factory and inspected for rot and other defects.  If it passes muster, it’s loaded onto a conveyer belt and into a machine that removes any stones or bits of potato stalk that may still be hanging around. 

Peeling

Next, a series of whirling wire brushes speedily removes the skin.  In this one process, our mid-sized spud loses half of its protein and fiber.  It retains much of its water, however, along with most of its vitamin C and vitamin B6, folate, potassium, and phosphorus.   It also hangs on to a whopping 4/5 of its carbs and calories. 

Slicing

The peeled potato is now dumped into a hopper and fed into a machine with several blades.  There, our medium-sized spud promptly yields about 40 very thin potato slices.  These slices are washed under running water and quickly dried.

Now these 40 raw slices, which collectively contain about 150 calories, are dumped into hot oil, where they stay for 4 to 6 minutes. As they fry, our 40 potato slices officially become 40 potato chips.  A thick cloud of steam rises from the oil, because this is the point at which the potato slices lose just about all of their water content and three-fourths of their weight.  But this is also the point at which they pick up some hitchhikers:  an additional 118 calories, and an astonishing 17 grams of fat.

Salting

Next the chips are salted, or doused in flavoring agents, or both. In the process, our 40 potato chips gain, collectively, about 284 milligrams of sodium. 

If all 40 of the chips from our original raw potato make it all the way through the process without being discarded for reasons of quality, they might end up divided between two small “snack-size” bags.  (A typical “snack size” bag of chips contains an ounce, or about 23 grams, of chips, which is roughly 20 chips.) 

You’ve Come a Long Way, Tater

Potatoes remain a staple of the American diet.  They may not pack the same nutritional punch as sweet potatoes (which are higher in fiber and, especially, carotenoids), but they aren’t simply the “empty” calories some folks believe them to be. 

If, however, you find that most of the potatoes that end up on your plate have first been peeled, sliced, fried, salted and bagged, take another look at the above chart.  Simply substituting a steamed or baked potato for that bag of chips at lunch will pay off big:  you’ll feel fuller and get more protein, fiber, vitamins and minerals while making huge cuts in sodium, fat and calories.