Roast potatoes are a cornerstone of any good roast dinner, no meal would be complete without them; yet, everyone has their own intricate process for achieving the perfect crispy and crunchy exterior.

Various methods can include different types of oil, goose fat, beef dripping, and in some cases, unconventional ingredients like mayonnaise. However, one food writer from Simply Recipe explained that one store cupboard ingredient is the key for the perfect roastie. And it's one that you may use for household cleaning hacks.

Simply Recipes' Molly Adams explained baking soda is the missing ingredient you should be using when cooking roast potatoes. Taking inspiration from chef J Kenji Lopez-Alt, she explained that there's science behind using baking soda.

Molly said: "While it may sound strange, this is a trust-the-process type recipe. When it comes to innovative and science-backed recipe development, there is no one I trust more than J Kenji López-Alt, so when he shared a recipe for extra crispy Parmesan-crusted potatoes on The New York Times calling for baking soda, I knew I needed to try it."

Kenji's recipe adds half a teaspoon of baking soda to approximately two litres of water, which is enough to cook around three pounds (approximately 450g) of cubed potatoes. The potatoes are then par-boiled in the baking soda water.

Once boiled, drain away the potatoes and roast them in a hot oven. Molly wrote: "The potatoes come out of the oven extra crispy, thanks to the baking soda."

So how does it work? As baking soda is an alkali, by adding it to the water for the potatoes, it creates an alkaline environment that breaks down the potato's outer edges, releasing starches to form a starchy slurry that crisps up beautifully when roasted.

Molly continued: "Why is creating a starchy surface on the potatoes so important? This slurry-like coating is what makes the potatoes so crispy. Once the shaggy potatoes hit the hot oven, the exterior gets super crisp while the inside of the potato stays nice and fluffy."

So instead of using baking soda for baking or home hacks, consider using the ingredient when rustling up your next roast.