Many people pay attention to ingredient pairing and seasoning when cooking, but overlook the crucial factor of oil temperature. In fact, temperature has a significant impact on the texture and nutritional value of a dish, and different dishes require different oil temperatures. Generally, cooking oil temperatures can be divided into three categories: hot pot with hot oil, hot pot with cool oil, and cold pot with cold oil. The "hot pot with hot oil" category further includes medium-hot oil, high-heat oil, and blazing oil.
Medium-hot oil. Commonly known as "five or six成热" (approximately 140°C~180°C). At this temperature, the oil surface ripples and churns towards the sides, with a hint of light smoke rising. When ingredients are added, a large number of bubbles appear around them, accompanied by a sizzling sound. Medium-hot oil is generally used for dishes like dry-frying and soft-frying, such as soft-fried shrimp, fried toon sprouts, dry-fried hairtail, and dry-fried pork tenderloin. Additionally, when stir-frying vegetables and meat dishes, the oil temperature should be controlled at five or six成热.
Dishes like dry-fried hairtail and dry-fried pork tenderloin require a second fry. This means the dish is fried until cooked, removed, and then fried again after the oil temperature has risen. For the second fry, an oil temperature of seven or eight成热 is needed to achieve a crispy outside and tender inside. Using medium-hot oil to stir-fry vegetables results in a beautiful color and minimal nutrient loss. If the oil temperature is too high, the ingredients may heat unevenly; if it's too low, vegetables tend to release water. When stir-frying meat dishes, first add the meat and stir-fry until it turns pale, then add scallions and ginger to continue stir-frying, and finally add other ingredients.
High-heat oil. Commonly known as "seven or eight成热" (approximately 190°C~240°C). At this temperature, the churning of the oil surface calms down, with light smoke visible. Stirring with a spoon produces a sound. When ingredients are added, a large number of bubbles appear, accompanied by a slight sizzling or popping sound. It is generally suitable for cooking methods like deep-frying, pan-frying, and stir-frying.
If you want a sunny-side-up egg with a golden, crispy outer skin and a runny yolk, you need to use seven成热 oil and cook for a short time. This temperature is also suitable for pan-frying tofu because if the oil is too cool, the tofu can break apart. After adding the ingredients, turn off the heat to set the outer skin with the high temperature, then use low heat to cook the inside through, and finally increase the heat to give it a golden color. This method is suitable for making dishes like candied yams and candied potatoes. Additionally, this temperature can be used to make crispy fried chicken, but you should not turn off the heat midway; maintain the temperature with continuous heating to achieve a crispy outside and tender inside.
Blazing oil. "Nine or ten成热" is also called blazing oil, with a temperature of about 250°C~300°C. It is dense with smoke, has a scorching hot air, and light smoke rises upwards, nearing its flash point. When ingredients are added, large bubbles surge up, accompanied by a loud popping sound. This oil temperature is only suitable for the final step of steamed dishes and boiled dishes, such as for boiled pork slices or scallion oil fish.
The method is to pour hot oil over shredded scallions, minced garlic, Sichuan peppercorns, and crushed chili flakes. This will create a sizzling sound, and the hot oil can splatter, so be careful.
Hot pot with cool oil. The oil temperature is three or four成热, approximately 90°C~130°C. The oil surface is calm, with no smoke or sound. When ingredients are added, a few bubbles appear with a light sizzling sound, and the oil temperature drops rapidly. This is used for making softer, more tender dishes, such as stir-fried pork tenderloin shreds and clear-fried shrimp.
To prevent the wok from dry-burning, you can first pour a small amount of oil into the wok, heat it to eight or nine成热, then pour the oil out. Next, add a suitable amount of cool oil and heat it to three or four成热. Dishes cooked using the "hot pot with cool oil" method are crispy and tender, and it also prevents sticking and nutrient loss.
Cold pot with cold oil. Add both oil and ingredients to the pot, then turn on low heat. This method is mainly used for deep-frying and is also called "swallow-frying".
Take fried peanuts as an example. First, put the peanuts and oil in the pot together, then gradually heat. Use low heat during the process. When you hear the peanuts popping and see their skins starting to crack and smell the aroma, immediately turn off the heat, pour out the oil, and quickly toss them in a strainer to release the heat. Sprinkle with salt and serve on a plate. Fried pine nuts and fried watermelon seeds are made using the same method.