A chef or caterer who has a busy day ahead may cut potatoes for French fries and place them in a large container of ice water in the walk-in overnight. The next day when these potatoes are fried, they get very dark and look done but are raw in the center. These potatoes fried perfectly the day before. What happened?
When potatoes (or a number of starchy vegetables) stay chilled for a period of time, some of the starch breaks down into sugar. Now, these higher sugar content potatoes brown much faster. The sugar and protein content, along with the acidity, determine how fast a food will brown. If left at room temperature for a day or so, the sugars will join back together to form starch. If you have whole potatoes stored at a cool temperature, you may want to leave them at room temperature a day before frying.
Cooks can use this little bit of science to make better low-fat oven fries. One of the problems with making fake French fries by roasting potato strips in the oven is that they get not so very brown. If you soak cut potatoes overnight in ice water in the refrigerator (maybe even add a little sugar), steam them a few minutes to partially cook, then toss them in something alkaline (less acidic) like slightly old egg whites, lightly beaten and sprinkled generously with herbs, cayenne, salt, pepper and a small amount of Parmesan, these potatoes will brown nicely in a hot oven. Be generous with the seasonings. Remember, one of the great problems with low-fat cookery is lack of flavor.
Shirley O. Corriher is a writer, author, biochemist, teacher and lecturer. She writes a column for The Los Angeles Times' "Great Chefs" series as well as articles in the Journal of Biological Chemistry. Her book Cookwise: The Hows and Whys of Successful Cooking is received a James Beard award.