June 5, 2013
When made just right, mashed potatoes are the ultimate comfort food: smooth, creamy, warm and filling.
But how to get them perfectly smooth and creamy?
Recently our research chefs perfected a modernist method that yields an amazingly smooth and slightly sweet potato puree, and all without adding any butter, milk or cream. The secret is to deploy a little trick of biochemistry that converts the starch in the potatoes into sugar.
The key is an enzyme known as diastase. Don't let the fancy name put you off; this ingredient is quite natural ( it is derived from malted grain) and you can buy it online or at stores that sell brewing and baking ingredients. It's typically is sold in a ready-to-use form called diastatic malt powder.
When you eat a starchy food such as bread or potatoes, enzymes in your gut help break down the starch into simpler carbohydrates (such as sugars) that your body can burn or store for energy. By adding diastase to our mashed potatoes, we're simply getting a jump on the process.
The trickiest part about diastatic malt powder is measuring the right amount. It's poten, so you really should measure ingredients by weight. After you have peeled and cubed the potatoes, weigh them. For every 100 grams of potatoes, measure out 1 gram of diastatic malt powder.
Now fill a pot with water and add 2 grams of sugar and 3 grams of salt for every 100 milliliters of water. Simmer the potato cubes until they are tender, 30 to 40 minutes, then drain. Stir the diastatic malt powder into the potatoes, then pass the mixture through a ricer.
The riced potatoes next get sealed in a zip-close plastic bag, which is set in a pot of hot tap water (about 125 F) for a half hour. The warmth activates the enzyme. When the 30 minutes is up, empty the bag into a pot, then heat the puree to at least 167 F (75 C) to halt the enzymatic activity.
That's it. Even with no butter or cream, the result is sweet and amazingly smooth. If you are avoiding dairy or limiting your intake of fats, this technique may just renew your love affair with the potato.
The Cooking Lab explores the delicious side of food science. It runs biweekly in Food.
MODERNIST POTATO PUREE
Yield: 4 cups
2 1/2 pounds Yukon gold potatoes 30 grams (2 tablespoons) salt, plus additional for seasoning 20 grams (1 1/3 tablespoons) sugar 10 grams (1 tablespoon) diastatic malt powder
Fill a large pot halfway with hot tap water. Set the pot over very low heat. Maintain the water temperature at 125 F. To hold this temperature, you may need to turn the heat on and off occasionally.
Meanwhile, peel the potatoes and cut them into 1-inch cubes. Measure out 1 kilogram (2.2 pounds or about 7 1/3 cups) of the potato cubes. Reserve any excess for another use. Place the potatoes in a second large pot with 2 liters (about 2 quarts) of water. Add the salt and sugar, then bring to a boil. Reduce the heat to maintain a simmer and cook until the potatoes are very tender, 30 to 40 minutes.
Drain the potatoes, then transfer them to a food processor. Add the malt powder, then process until smooth and sticky. Transfer to a large zip-close plastic bag, pressing out as much air as possible before closing. Place the bag of potatoes in the pot of 125 F water and cook in this manner for 30 minutes.
Empty the potatoes from the bag into a clean pot, then heat gently to at least 167 F. Season with salt and serve immediately.
NOTE: As with most modernist recipes, accuracy is key. We've provided volume equivalents of most ingredients, but for best results use a digital scale and weigh things out. Diastatic malt powder is the secret to making these dairy-free pureed potatoes smooth and creamy. It is widely available online, as well as at brewing supply shops.