International Chef Day | Can you finish three bowls of the meal cooked by the chef? Don’t ignore the tricks behind the “delicious” meal!

Tired from school, tired from work, tired after waking up, tired after playing... How can we comfort ourselves from so much "tiredness"? The first choice, of course, is to enjoy (crazy) delicious (dry) food (meals).

October 20th of every year is International Chefs Day. For foodies, the delicious food made by chefs makes them salivate. There are a lot of traffic on the Internet for exploring restaurants and eating live broadcasts, and the voices of "so delicious" are heard everywhere.

But we often overlook:

Why does the food cooked by the chef taste so good?

Is “delicious” food nutritious?

What impact does it have on our health?

Today, we will reveal the secrets behind “delicious”.

01 Are stir-fried dishes really delicious? But the nutritional value suffers!

Why is the fried rice in restaurants always so fragrant? Why are the stir-fried dishes in fast food restaurants so flavorful?

Because chefs know how to use the technique of sautéing the wok.

For a fragrant Chinese stir-fry, put the ingredients into the wok and stir-fry until they are evenly cooked. At this point, most housewives will take the wok off the stove. However, if it is a chef, he will turn to high heat at the end, stir-fry quickly at high temperature, and suddenly the whole dish is full of fragrance.

The reason is the combined effect of high temperature and oil.

High temperature not only makes various seasonings absorb faster, but also makes food mature faster; the presence or absence of fat has a more obvious impact on the taste of dishes, such as: celery fried pork, garlic sprouts fried pork shreds are more delicious than just stir-frying celery or garlic sprouts. In summary, it is more oil and more fire. This is why you feel that the dishes cooked by chefs are more fragrant than the dishes cooked at home.

Stir-fried green onions and peppers (Photo source: Tuchong Creative)

Don’t smell it! Stir-frying food will destroy the nutrients in the ingredients!

● Water-soluble nutrients : During the sautéing process, a relatively high temperature is required, generally between 120 degrees Celsius and 170 degrees Celsius. Such a temperature will not only cause the loss of water-soluble nutrients, such as B vitamins and vitamin C;

●Fat-soluble nutrients : During the stir-frying process, fat-soluble nutrients such as vitamin A, vitamin D, vitamin E and vitamin K may be lost due to the high temperature. Fat-soluble vitamins are sensitive to oxidation and can be easily decomposed by long-term high-temperature cooking . For example, when frying carrots, high temperatures will cause the loss of vitamin A in carrots. To reduce the loss of fat-soluble nutrients, the cooking time should be shortened as much as possible and stir-frying should be used quickly.

● Protein : Protein may change quality due to heat and lose its biological activity.

● Oil : Stir-frying will also lead to oxidation of oil at high temperatures. Oxidation of oil will produce harmful substances that are harmful to human health, such as lipid peroxides and acrylamide. At high temperatures, oils are prone to reaching the smoke point and deteriorating, reducing their nutritional value. Therefore, to avoid oxidation of oil, you should choose oil with a higher smoke point and control the heat to reduce the generation of oil smoke, such as sunflower oil, peanut oil, etc.

02 Is it troublesome to stir-fry sugar color? Controlling blood sugar is the key!

It is said that braised pork has a bright color and is very popular. This actually involves a unique cooking technique - stir-frying sugar color, which is to heat white sugar or rock sugar in a pot to turn them into a dark brown liquid, and then use it to color or add fragrance to dishes.

Braised pork (Image source: Wikipedia)

Sounds simple? But in this process, many complex chemical reactions occur. The essence of frying sugar color is caramelization reaction, which is mainly divided into two steps:

●Heating: Thermal decomposition of sugar

Sugar molecules are organic substances composed of carbon, hydrogen, oxygen and other elements. Common sugar ingredients include white sugar, rock sugar, brown sugar, yellow sugar, etc. When sugar is heated, its molecular structure changes, and the carbon, hydrogen and oxygen atoms in the sugar molecules rearrange to produce new chemicals.

During the process of frying sugar color, the sugar ingredients will be heated at high temperature, and when the melting point of sugar is reached, it will begin to melt, and its internal molecular structure will change, and the sugar molecules will be reorganized into larger molecular structures. This process will release a lot of heat, causing the temperature of the sugar ingredients to rise rapidly .

●Coloring: Coking reaction

Next, as the temperature continues to rise, some of the carbon atoms in the sugar molecules will break away from the sugar molecules to form a mixture called caramel, which is called a carbon thermal chemical reaction, also known as a carboxylation reaction.

Caramel is a complex compound composed of a large number of carbon atoms, showing a special brown-red color, which contains a small amount of water and some low-molecular sugar alcohols. More importantly, during the caramelization reaction, smaller and more volatile molecules are produced , such as furan, maltol, ethyl acetate, diacetyl , etc. , which "contribute" a lot of aroma and flavor to caramel:

▶ Furan’s “contribution”: Nutty flavor

▶Maltol’s “contribution”: roasted flavor

▶Ethyl acetate’s “contribution”: fruity and aromatic

▶Diacetyl's "contribution": buttery taste

Does it make your mouth water? Don’t rely too much on dishes with beautiful sugar colors!

The caramelization reaction requires a relatively high temperature (generally above 140-170°C), which will cause some loss of nutrients in the ingredients.

This is not the same as sautéing the pan. The effect of caramelization is mainly the color and flavor mentioned above. Partial loss means that while we take advantage of the advantages of caramelization, we should not rely too much on this method. Therefore, we should not rely too much on stir-fried caramelized dishes, change the flavor more, and be more loyal to the original taste of the ingredients.

For people with poor blood sugar control, it is not recommended to frequently eat fried sugar-colored dishes.

The World Health Organization recommends that the sugar intake of adults and children should be controlled below 10% of total energy intake, which is equivalent to no more than 50 grams of sugar per day. It is best to control it below 5%, that is, no more than 25 grams. The "Dietary Guidelines for Chinese Residents" also advocates that adults should not consume more than 50 grams of added sugar per day, and advocates that the public should use scientific dietary knowledge as a guide to reasonably control sugar intake.

03 Overcooking makes the food taste strange ? Carcinogens are secretly happy!

Occasionally we see in restaurants that when the chef is frying a dish, he puts the vegetable into the wok, stirs the spatula, and flames appear. The smooth stir-frying is very satisfying to watch!

This technique of making the wok spit out fire is called "hot" or "overcooking" in cooking terminology, which is actually tossing the wok over high heat. Generally speaking, dishes that need to be stir-fried and have a dark color and strong flavor need to be overcooked, because stir-fried dishes are cooked at high temperature in a short time, so that the taste requirements of the dish can be achieved (for example: crispy, tender and refreshing).

When cooking, the moisture in the food comes into contact with the hot oil, and oil mist will explode. The higher the temperature, the larger the oil mist will be. When flipping the wok, the chef will pull the wok back and the food will be pushed forward, so the oil mist will also follow to the front of the wok. When the wok is pulled back, the front of the wok will touch the flame, and the oil mist will be ignited, which is overcooking.

Overcooking is also called "overcooking" (Photo source: Tuchong Creative)

The standard for judging whether it is overcooked is actually related to the burning point of the oil. Due to the different fatty acid content, the burning point of different oils is different. For example, the burning point of sesame oil is 215℃, the burning point of peanut oil is 226℃, the burning point of corn oil is 246℃, and the burning point of soybean oil reaches 257℃!

Such a high temperature will not only cause the food to lose some nutrients, but also produce some substances that are harmful to the body .

(1) Carcinogens

When starchy foods are exposed to high temperatures, acrylamide (a Class 2A carcinogen ) is easily produced;

When protein-rich foods encounter high temperatures → heterocyclic amine carcinogens are easily produced;

When fatty foods encounter high temperatures, they are prone to produce carcinogens such as benzopyrene .

(2) Trans fatty acids: Such high temperatures will also produce trans fatty acids, leading to obesity, increased blood lipids, and increased risk of cardiovascular disease.

Having said so much, I just want to say in this era where taste is king: Don’t just keep “eating well”! Healthy eating starts with you and me.

References

Wang Wenwei. Analysis of the influence of cooking methods on food nutrients and protection measures[J]. Food Safety Guide, 2023, 15 :145-147

Ma Mengtian, Wang Minghui, Zhang Guixiang, Zhang Bingwen. Research on the influence of traditional Chinese cooking methods on food nutritional quality[J]. Food Industry, 2023, 44(2): 208-213

Zhang Mengjun, Hou Fang, Li Yihou. Strategies to reduce nutrient loss in cooking[J]. Modern Food, doi:10.16736/j.cnki.cn41-1434/ts.2021.04.027

Lie Hongyan. Nutritional and scientific Chinese cooking[J]. Modern Food, doi:1; 0.16736/j.cnki.cn41-1434/ts.2017.14.013

Author: Tian Weina , Associate Professor, Registered Dietitian of Chinese Nutrition Society

Produced by: Science Popularization China

Produced by: China Science and Technology Press Co., Ltd., China Science and Technology Publishing House (Beijing) Digital Media Co., Ltd.