Frying is a cooking technique in which food is cooked by submerging it in hot oil or hot liquid fat. It is a common cooking technique across cultures; however, it has got a bad reputation for being an unhealthy cooking technique as food that is fried absorbs excess fat. Frying cooks food fast and, as it involves no water, the technique is considered a dry one. Stir frying is a more popular form of frying today and extremely popular with the health conscious. The technique involves using very little oil, but food is cooked over high heat. This technique is traditional to Asia, but is now popular the world over.
How Frying Works?
When food is immersed in hot oil, it converts the moisture in the food into steam. The steam forms a barrier preventing the oil from penetrating. The barrier is also strengthened by the crisp browned exterior of the food, especially if it is dipped in a batter. The steam then cooks the food inside the crispy exterior.
Temperature control is the key to effective frying. If the oil temperature is too low, the moisture escapes slowly and surface will take longer to brown. If the exterior surface does not create a strong barrier, oil gets absorbed in the food and results in greasy food. If the oil is too hot, the outer surface will brown very fast, but the internal temperature will not rise enough to finish cooking and the food will remain undone. 
Frying is a delicious way to cook food and done smartly can even make it a healthy and flavourful cooking technique. Here are some tips:
- Use neutrally flavoured oil, such as safflower or peanut oil, as the food tastes best and retains most of its natural flavours.
- Avoid vegetable oil or shortening and lard, as both are fattening.
- Use enough oil so as to cover whatever item you intend to fry.
- Make sure you place the pot, pan or wok of oil over a high heat and let it heat well.
- The oil should be at 365°F or 185°C when you fry any food item.
- Oils will begin to burn between 400°F and 450°F or 200°C and 225°C, and can catch fire at a higher heat, so it’s important to monitor the temperature.
- When the oil is hot enough, reduce the heat marginally. Remember, when you add food the temperature will drop.
- Never drop too much food in the oil, or the oil’s temperature will drop dramatically, the food will stick together and be greasy.
- Use a mesh spatula to remove the cooked items and let them drain on paper towels or cooling racks.
- Use coatings on foods that are too moist to brown evenly on their own, such as fish and vegetables. Fried directly, these may burn before browning and turning crisp. The coating can range from a simple dusting to a batter.
- Almost anything can be fried in batter, be it thin slices of vegetables, meat, chicken, fish, fruit such as bananas, greens such as spinach, and even ice cream.
Is It Healthy?
Frying has a poor reputation in terms of health, but because it is one of the fastest ways to cook, vegetables high in vitamins, such as broccoli and carrots, often retain their nutrients, as well as their texture and colour.
Prolonged frying over high heat, however, can destroy nutrients. The key to ensuring that fried food in not unhealthy is to ensure that food is fried at the right temperature.
When oil reaches a very high temperature, it becomes toxic and be unfit for consumption. Oil that smokes should be thrown away. Other signs that oil is not fit for consumption are when it darkens, foams or becomes thick.
Is It Energy Efficient?
Frying can be an energy-efficient cooking technique, provided it is done in the right utensil. A Chinese wok or an Indian kadhai is the ideal shape to fry in, be it deep fry or stir fry. Such vessels use a small amount of intense heat to quickly fry food. The deep, rounded, conical shape distributes the heat well and makes ideal use of a gas burner. The flame reaches around the gently sloping sides and heats the utensil right up to the top. However, the wok cannot be used in an electric kitchen.
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