The Man Who Ate Everything - Jeffrey Steingarten [25]
I used only large mealy Idaho russets in my mashed potato experiments. Avoid recipes that fail to specify which type of potato to use. Also avoid recipes that call for something like “six medium potatoes” without giving their total weight. Potatoes vary in size even more than human beings. If the cookbook specifies neither potato type nor total weight, discard it immediately.
Peeling and cutting your potato. The potato-peel lobby would have you believe that all the nutrients are in the skin. Nothing could be farther from the truth. The peel does contain a disproportionate share of vitamins and minerals compared to its negligible weight, but most of the nutrients are nonetheless found in the flesh of the potato and not in the peel. Cooking a whole potato in its peel does prevent some vitamins and flavor from leaching out into the salted water, but cooking any potato whole, whether you peel it or not, leads to uneven cooking when the rounded ends and outside layers become overcooked before the inside is ready. Overcooked cells will rupture.
If you peel your potatoes and cut them into pieces of the same size, they will cook evenly and quickly. Tiny pieces cook fastest but lose more nutrients and flavor because their total exposed surface area is larger. The best compromise is to cut peeled potatoes into slices between five-eighths and three-quarters of an inch thick. Wash them under cold water to rinse off any free starch released when you cut open the cells in peeling and slicing.
Cooking your potato. This is where we part company from all domestic mashed potatoes that have gone before us.
Years ago the instant mashed potato industry found that if you precook potatoes in 163-degree water for twenty minutes (twice as long for waxy varieties) and cool them, the amount of free starch in the final mash will be reduced by half. Without this discovery the instant mashed potato industry would today be manufacturing laundry starch.
I have experimented with both techniques and am guardedly optimistic that precooking may be the answer to our prayers. It appears to work like this. Cooking a potato is a two-stage process. The starch swells and gelatinizes within the cells when the potato reaches 160 degrees; then, nearer to the boiling point, the pectic cement between the cells degrades, and the potato can be safely mashed. Precooking separates these steps. Cooling the potato slices after the starch has gelled causes a process called retrogradation to take place; the starch molecules bond to one another and lose much of their ability to dissolve again in water or milk, even if you later rupture the cells through ricing or mashing and even if you overdo the final cooling a bit. Retrogradation retards gumminess.
For the first time anywhere industrial precooking and retrogradation can now be brought into the home kitchen. The use of a thermometer is vital. Put the peeled and washed slices into a pan of 175-degree water. Keeping the pan on a low flame and adding a little cold water now and then, you will find it easy to maintain the water within a few degrees of 160 for the next twenty or thirty minutes as you go about your other tasks. The slices will become tough and resilient and lose their translucent appearance. Drain the potatoes and transfer them to a bowl into which you run cold tap water until the slices feel cool to the touch, and leave them there for the next half hour. Then proceed to the final cooking, either simmering or steaming. Some recipes have you put your potatoes into cold salted water before bringing them to the boil. An elaborate Swedish study has shown that potatoes cooked this way produce a stickier final mash and sometimes develop an odd flavor. Other studies demonstrate that more vitamin C is lost if you start with cold water. Better drop your potato slices into actively boiling salted water and lower the heat to just above a simmer.
Last night I tested four versions of mashed potato on my guests. The precooked version came in first. It was smooth, not gummy, and had