Cooking tips from the world of food physics

Cooking tips from the world of food physics

The terms “crunchy” and “crunchy” are often used interchangeably to describe the texture of certain foods, but did you know that they are actually different?

Crunchy food — which tends to break down quickly and easily in our teeth — makes a high-pitched sound at the point of impact, says Sophia Rodrigues, a food physicist at the University of Waikato.

She talks to Jesse Mulligan about sharing tips for improving the texture of baked potatoes and pavlovas.

Grilled potato

Grilled potato
picture: Pixabay

Sofia Rodrigues - Food physicist at the University of Waikato

Sofia Rodrigues – Food physicist at the University of Waikato
picture: University of Waikato

Food physicists consider the things we eat “materials,” Rodriguez says, and their job is to figure out what happens when they are pressed between our teeth while we eat.

In the world of food physics, “crunchy” and “crunchy” are measured by the mechanical force needed to compress the food until it breaks into small pieces, how easily it breaks, and the fragility of the food itself.

Crunchy foods tend to be dry and hard, Rodriguez says. When we bite it – usually with the incisors – a relatively high-pitched sound is emitted.

Crunchy foods, on the other hand, tend to be dense and chewy. When we chew – usually with our molars – it “undergoes a series of fractures” and produces a relatively low-pitched sound.

As an aspect of food, they are among the most common “textural features” globally.

“Not everyone will like the chewy or dry texture…but with the crunch and crunch they say everyone usually likes it.”

“We usually associate the presence of crunch and crunch in a meal with high-quality cooking,” says Rodriguez.

“If it is present in the dish, it usually enhances or contrasts the texture to make it more interesting and enjoyable.

“If you are a fan of cooking shows like Chef Maybe this is not news to you. A lot of winning dishes will have more than one texture on the plate.”

To get the insides of baked potatoes “nice and soft and fluffy,” Rodriguez says, they should be parboiled before roasting them in the oven.

She recommends adding a little baking soda to the water you’re partially boiling it in.

“It helps break down the pectin. Pectin is like the glue that holds the cells of the vegetables together, (similar to) the mortar between bricks. You want to break down that pectin to form a starchy slurry on the outside of your potatoes that will then dry and form a crunchy coating when cooked.”

Rodriguez says cooking roast potatoes to 230 degrees Celsius should give them the perfect crispy outside.

Pavlova with rose cream, cardamom and salted caramel pieces

Pavlova with rose cream, cardamom and salted caramel pieces
picture: s

  • Cooking tip for pavlova: Add a little corn flour

Sometimes, a pavlova — also known as the “oven-fried egg shape” — can become sweaty due to humidity and its surface becomes soft and sticky, Rodriguez says.

To give your puff “a little more resistance to wet weather,” Rodriguez recommends adding a little cornmeal to your mixture.

“The starch will absorb any water in the pavlova.”

Fine, not granulated, sugar also improves the texture of the pavlova.

“When the sugar dissolves in the water of the egg white, it increases its viscosity. This is how this nice glossy meringue is formed instead of the brittle egg white shape. It strengthens the interaction between the air and water and allows you to create a smoother meringue. It disperses the air bubbles.”

“They say the more sugar you add, the thicker the pavlova will be and the crunchier it will be when baked. But of course, you don’t want it to get too sweet.”

Puffs are best baked low and slow, says Rodriguez. Think 110°C for at least an hour, maybe two hours.

“You dry the model slowly, you just evaporate the water out of it, you don’t supplement the sugar.”

    (tags for translation) Radio New Zealand 

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