According to chef Vu Nhat Thong from Eric Cooking Class, when food comes into contact with sufficiently hot oil (above 170 degrees Celsius), the water inside the ingredients instantly evaporates, creating a continuous outward steam flow.

This steam acts as an invisible protective barrier, preventing oil from soaking back in. Simultaneously, the Maillard reaction occurs rapidly within the first few seconds, helping to form a sealed, crispy crust on the surface.

Conversely, when the oil has not reached the standard temperature (below 160 degrees Celsius), water in the ingredients evaporates slowly, allowing oil to easily penetrate and fill the food's empty spaces. The outer crust also forms slowly and thinly, making it insufficient to prevent absorption, resulting in a dish that is both oily and not crispy.

Chicken is often double-fried for extra crispiness and less greasiness. *Photo: AI*

Standard temperatures for different ingredients

However, chef Vu Nhat Thong also advises that high heat does not necessarily mean the oil is hot enough, and each type of food requires a different temperature for perfect cooking:

- 160 - 165 degrees Celsius: Suitable for vegetables, tofu, and thin, easily cooked ingredients. A sign of this temperature is when the oil gently ripples if a wooden chopstick is dipped in.

- 170 - 175 degrees Celsius: The standard temperature for chicken, shrimp, and fried spring rolls. When tested with a wooden chopstick, bubbles will immediately rise evenly.

- 180 - 185 degrees Celsius: Used for frying potatoes or foods requiring a thick, crispy crust. Bubbles will rise strongly and continuously around the chopstick.

- Above 190 degrees Celsius: At this excessively high temperature, the food's outer crust can easily burn while the inside remains undercooked. Additionally, if unrefined oils are used, this is their smoke point, causing the oil to ignite and produce acrolein and other harmful compounds.

Double-frying technique

To ensure food remains crispy for longer, like in restaurants, professional kitchens often use the double-frying method, especially for fried chicken.

In the first fry, food is cooked at 160 degrees Celsius for 6-8 minutes to cook the interior and form the outer crust. Afterward, the ingredients are removed and allowed to rest for 3-5 minutes. This process allows residual heat from within to continue spreading outwards, naturally drying the surface.

In the second fry, the oil is heated to 185 degrees Celsius and the food is fried quickly for 2-3 minutes. This high temperature evaporates any remaining moisture, helping the crust turn golden and crispy without absorbing new oil, as the surface was already sealed from the first fry.

Temperature control is the rule that determines the quality of a dish. Only when fried at the correct temperature will food truly be less greasy.

Bao Nhien