Potatoes are a fundamental ingredient across Latin American cuisine. This tuber stars in countless dishes but can be technically challenging to cook to the ideal texture at home. Many home cooks try to recreate the restaurant finish—known for a crispy exterior and a tender interior. The secret appears to be an everyday ingredient that chefs began using successfully during the 2020 lockdown: baking soda.
American cook J. Kenji López-Alt, a leader in culinary experimentation, popularized this technique after studying British cooking habits. In Britain, cooks often parboil potatoes with added fat to create a starch film that browns and crisps in the oven.
Roast potatoes became popular in bars, often served with beer. Photo: Zak Chapman / Pexels
López-Alt substituted the fat with baking soda after identifying a key chemical reaction. As he explained on the food website Serious Eats, the solid compound breaks down pectin—the cellular “glue” that holds vegetables together. By weakening that structure during the boil, the pieces don’t fall apart prematurely and a starchy coating forms on the surface.
The method’s core is adjusting the pH of the cooking water. López-Alt notes the process depends on an alkaline balance: “The lower the pH—that is, the more acidic—the less it will break down. Conversely, the higher the pH—that is, the more alkaline—the faster it will break down,” he explained in his technical analysis.
Based on that insight, he recommends adding just one tablespoon of baking soda to the water. The reaction creates an environment that speeds the surface breakdown of the tuber, producing the thin starchy layer needed for the desired oven crispiness.
However, the technique requires precision. The chef warned that how the potatoes are cut is crucial for success: pieces should be large and similar in size.
If the pieces vary too much, the alkaline water can work against the result and damage the dish’s integrity. The basic principle for the expert is simple: “Alkaline water helps the potato exterior break down more, creating more of the starchy paste that yields an extra-crispy exterior.”
The key to crisp roast potatoes is parboiling them with one tablespoon of baking soda added to the water (Source: Pexels)
This discovery, supported by food science, changed how cooks approach the bar staple side dish. Combining the baking-soda parboil with a high-heat finish in the oven achieves a texture that once seemed exclusive to professionals. The technique is simple, inexpensive, and effective for anyone wanting to improve home results by changing one basic step of the traditional cook.
Step-by-step method to make roast potatoes:
Cut the potato into pieces of the same size.
Start them in cold water so heat penetrates slowly toward the center; at the same time, add one tablespoon of baking soda to the water.
It is suggested to use one tablespoon of baking soda per two liters of water.
Bring the water to a boil and let it simmer for five minutes.
Remove from heat, drain, and place the potatoes in an oven dish.
Roast in a preheated oven at 200 °C (about 400 °F) for at least 20 minutes.
Remove and carefully turn the pieces to expose the und browned sides, then return to the oven for another 20 minutes or until fully golden.
Remove and season to taste.
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