The sizzling secrets of frying: Sound Bites with Swetha Sivakumar

BySwetha Sivakumar
Aug 04, 2023 09:16 PM IST

Most oil isn’t absorbed by food while it is submerged; it’s absorbed later. Bubbles hold the key to how much oil is sucked in. Why? Take a look.

Why is it that baked goods never have the flavours, textures and aromas of fried snacks?

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The temperature isn’t the issue. Ovens easily go as high as 160 to 200 degrees Celsius, which is the range at which most frying occurs. So what is it that changes, when heat is conducted by air (as in an oven), rather than by oil (as when frying)?

Another way to frame the question, one that also hints at the answer, is: Why we can put our hands in a hot oven, but not in boiling oil?

The answer is that the molecules in air are not bound as closely to each other as the molecules in liquid oil. As a result, while the ambient temperature in an oven may be 200 degrees Celsius, the food is not experiencing these temperatures across its surface at all times. This is why oven-roasting also takes longer than frying. (The extended exposure to dry heat is also why ingredients dry out in an oven, ending up with a less-desirable mouthfeel, rather than the juiciness of many fried foods.)

The big problem with frying, of course, is the vast amounts of fat that one is forced to consume. Studies have shown, interestingly, that only a fraction of that oil , sometimes as little as 20% , soaks in while the food is immersed; most is sucked in after the item has been taken out of the pan. This is why manufacturers use massive metal spinning tubs to “de-oil” their snacks. At home, this is why our parents laid out paper towels or put such snacks in strainers to drip-dry as they cooled.

Why is most of the oil absorbed post-frying? To understand this, we must zoom in on what’s happening in the pan. Since temperatures here are much higher than the 100 degrees Celsius boiling point of water, as soon as food is submerged in hot oil, the water inside begins to turn to steam. The steam carries a lot of energy. It travels both inward, cooking the inner layers, and outward, as bubbles that leave tiny craters behind.

As long as there is moisture in the food, the bubbles will continue to form. The jets of steam pushing out from the surface actually prevent oil from entering. Once the bubbling stops, however, the oil on the surface is sucked in, in a process called vacuum absorption.

This is why snacks coated with a wet batter, such as bhajjias and bondas, absorb more oil than drier foods such as papad. Watery batters make for more steam, more bubbles, and more pores. You can almost squeeze the oil out of these snacks when they’re done.

Raise the amount of protein and insoluble dietary fibre in the dough, and it instantly alters how much oil is absorbed. Add about 14 gm of a high-fibre flour such as wheat or oat bran to 100 gm of refined wheat flour for puris, for instance, and oil absorption can drop by up to 20%. (The condition of the oil makes a difference too. Click herefor more on this.)

The worst thing one can do, is double-fry foods (something that is increasingly popular with everything from vadas to French fries, as a way to get that added crunch). With two cooling-off periods, oil absorption is maximised in foods that are cooked in this manner. Follow the double-fry method often enough, and one might as well simply sip the oil from a cup.

(To reach Swetha Sivakumar with questions or feedback, email

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