Potatoes are one of the best tasting carbohydrate-rich foods, when cooked. (Well, raw potatoes are hardly digestible, in the first place). This is especially true if they are fried (French fries, anyone?) A good reason for this is that cooked potatoes are rich in umami compounds. For a quick review, umami is the 5th basic taste that is best described as brothy, meaty, and savory. This taste is associated with seaweed, meat, mushrooms, aged cheeses, tomatoes, among others. For more on umami, visit this article.
To date, studies have identified at least 220 aromatic molecules that contribute to the flavor of a cooked potato. To bring out their best flavors, potatoes can be boiled, fried, mashed, and even roasted. But no matter the cooking method, it is advisable to soak them first in water. Sliced potatoes can be soaked in water for several hours up to a couple of days (in the refrigerator). And soaking them is for good reasons.
SOAKING OF POTATOES GET RID OF EXCESS STARCH
We do not cook whole potatoes, right? When we cut them into smaller pieces, we also release those components originally locked within the inside of the potato. But some of them may interrupt during the cooking process. To better explain this, let’s take a quick look at what comprises a potato.
According to the United States Department of Agriculture, a typical raw potato is 79% water and 16% starch. Starch is our main source of carbohydrate, the macronutrient that provides energy to our body. While sugar is a single carbohydrate, starch is a complex one—it is composed of a long chain of sugar molecules. When we slice a potato, we are exposing some of the starch, along with the other components. The problem is that excess starch may interfere during cooking, making the potato slices sticky on the outside.
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One type of starch in potatoes is amylose, the one responsible for the gluey texture of mashed potatoes. In the presence of water, amylose molecules break down, whereas amylopectin molecules, another type of starch in potatoes, remain compact. So during washing and soaking, amylose is what we are removing. If excess amylose is not removed, the potatoes may be cooked unevenly. During cooking, heat makes the starch to swell in a process called gelatinization. This makes the potatoes to more likely to stick together. But proper soaking will prevent this to happen, resulting in potatoes that cook or fry much better— not sticky, but crispier. Just make sure potatoes are soaked in cold water. Soaking them in hot water will only activate the starch. Remember that starch gelatinization activates in the presence of heat.
SOAKING ALSO REDUCES ACRYLAMIDE FORMATION
In 2002, a group of scientists was studying the Maillard reaction when they found acrylamide in foods. Acrylamide is a compound that forms when food is cooked at a temperature of 284 °F (120 °C). A product of the Maillard reaction, acrylamide usually forms when the amino acid asparagine and reducing sugars react. Studies have found it to occur in foods such as potatoes, biscuit, cereals, and coffee. However, acrylamide forms at high levels in highly processed food like French fries and potato chips. One study has found that French fries and potato chips can have up to 1325 and 2762 parts per billion of acrylamide, respectively.
Acrylamide is feared because it is a potentially carcinogenic compound. Although present studies have not yet known its full impact on the human diet. Since its discovery in 2002, efforts have been made to reduce its levels in various foods. The Food and Drug Administration (FDA) recommends cooking food until golden yellow. Generally, foods cooked until brown tend to contain more acrylamide. When toasting bread, a light brown color is better than dark brown color.
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Prior to cooking potatoes, one way to reduce acrylamide formation is soaking them in water. According to the FDA, soaking potatoes in water for 15 to 30 minutes is sufficient to reduce the levels of acrylamide during cooking.
In the March 2008 issue of the Journal of the Science of Food and Agriculture, a study involving soaking potatoes in water proved this to be true. The researchers washed and soaked raw French fries for 30 minutes, and then for 2 hours. This decreased the levels of acrylamide by 23% and 48%, respectively. But this is only achievable if the fries were lightly fried.
