Too much Misinformation is Spread About Deep-Frying and it is Time to Look at the Facts
Sam Sinha set out to write a short paragraph on the misconceptions surrounding deep-frying but found there was a lot to be said in defence of the technique
I understand the concerns
Hot oil and flame is a lethal combination. Deep-frying can be smelly and messy. Fried foods can be greasy, full of fat and high in calories.
So why am defending the deep-fat fryer?
The wording is important. This is a defence not an outright endorsement. I’m not suggesting that frying is the answer to all our problems and will make us all slim and healthy. But far too much is said about frying without any basis in fact.
I think there is a place for frying in our lives and seek to enlighten cooks everywhere to the joys and benefits of deep-frying. It can be an easy, clean, healthy and refined way to produce good, tasty food.
Let’s take a look at the science of frying
Deep frying in fact has more in common with baking than with pan frying. Hot oil comes into direct contact with the surface of the food but internally, it is hot water vapour that is doing the cooking. In an oven, the same thing is happening only it is the hot air, instead of oil, that contacts the surface of the food. In both cases the heat source completely surrounds the food providing even cooking to the surface. Except that a conventional oven is much more susceptible to hot and cold spots; as is a frying pan.
When pan-frying, the heat only comes from below. Even cooking is what we are looking for; this gives consistent temperature transfer and ensures even doneness through to the core.
This is why deep-frying is the only way to get an even, crispy, golden crust
There is a misconception that deep-frying is a lowly kitchen technique but when done right it can be produce beautiful results. A good example of this is battered fish. Fish should always be cooked with great care as it starts to overcook at about 60°C.
Amazingly, battering the fish and deep-frying, even at 200°C, is a great way to achieve a perfectly and gently cooked piece of fish. The batter actually protects the fish from the intense heat of the oil while inside, the fish is cooked by its own moisture.
The temperature of the water vapour inside is far lower than that of the oil so the fish steams gently while the batter turns golden brown and crispy in contact with the oil. The stream escapes from the fish through the hot oil and this can be seen as bubbles in the oil and “smoke” rising from the surface. By using the right thickness of fillet, the result can be a perfectly cooked piece of fish that reaches around 55°C at its core just as the batter turns golden brown.
Deep-frying can also be useful for crisping foods that have already been cooked to a desired temperature. This is how chips are made to be fluffy and soft on the inside and crisp on the outside. They are “blanched” in oil at 140°C until soft then quickly fried at a high temperature to crisp the outside.
The same technique can be used to achieve perfectly cooked meat, fish and vegetables with crispy exteriors. The foods can be poached in water, cooked sous vide at low temperatures or steamed to cook through and then fried at a higher temperature of 200°C to achieve a golden caramelised crust. This is a technique employed by some of the best regarded restaurants in the world so should not be overlooked through misinformed snobbery.
What about the safety issue?
Chip pan fires are extremely dangerous and I do not take the risks lightly. However, there is no reason that deep-frying cannot be enjoyed, perfectly safely at home, with minimum effort and mess. There are a few key points to get right.
Use a heavy bottomed, high sided pot
Oil gets a lot hotter than water and a weak pot may not be able to take the high temperatures. High sides mean the oil is less likely to overflow or spit everywhere.
Do not overfill the pot!
The food you put in will displace the oil and if the pot is too full it will overflow when the food is placed inside. Very hot oil spilling onto gas flames is very bad. Use enough oil so that the food will be generously covered. If needs be fill the pot with water and dip the food in to see where the water level end up. Then you will know how much oil to use.
Use a thermometer
You don’t want to fry above 200°C so if the oil goes much beyond this just slide it off the heat until the temperature goes down. Oil retains heat very well so does not need to be on the flame constantly to stay hot. If you don’t have a thermometer you can test the temperature by adding a little piece of batter or whatever you have and see how it reacts. You should be able to tell when it is ready to cook by how much steam comes off etc. If the oil is smoking it is too hot.
When you’re finished leave the oil to cool in the pan.
Later it can be strained and decanted back into its container but plastic doesn’t deal well with hot oil.
Use the right oil
Commonly used are blends of vegetables oils or sunflower oil. These are ideal as they are relatively inexpensive and have high smoke and flash points. This means they won’t turn your kitchen into an inhospitably smoky environment or catch fire when heated to cooking temperature.
Olive oil and rapeseed oil have smoke and flash points above 200°C as well though, so really it comes down to a choice of how much money you want to spend versus the flavour imparted into the food. Olive oil will give off more flavour than a vegetable oil blend.
Another consideration is the melting point if the fried food is to be served cold. This will affect the mouthfeel of the food when eaten. For foods like vegetable crisps, you want a melt-in-the-mouth feel which means the oil’s melting point should be at or below our body temperature (around 37°C). Any vegetable oil like sunflower, olive, or grapeseed oil will achieve this. However, for something like a glazed donut, an oil with a high melting point should be used so that the glaze does not crack or run.
Is deep-frying always bad for me?
Whilst it’s true that deep-frying can add calories to your food, there’s a lot that can be done to minimise this. Some foods will take on a lot of the oil when being fried, things like battered foods and chips undoubtedly soak up oil. But frying can be an excellent way to cook vegetables or meats which when sliced thinly, will crisp up and cook through quickly but won’t retain very much of the oil they were cooked in.
Simply maintaining the oil temperature and draining the food properly after cooking can reduce the amount of fat soaked up dramatically
Maintaining the oil temperature is important as this is what creates the right environment for the outside of the food to crisp. The temperature of the oil will drop dramatically if cold food is added. It will take time to recover and the desired effect of frying the outside to a golden crisp won’t be achieved. This will result in soggy food that takes on more of the oil.
The solution is to bring food up to room temperature before frying and get the oil to a slightly higher temperature than you want to cook so that when it drops, it drops to the desired temperature.
Draining on paper means the food sits in the oil saturated paper and will leave you with a soggy exterior and more fat left in the food. Its better to drain on a wire rack with paper underneath so that the oil can drip away and the food dries in the air and stays crispy.