Fried! Grilled! Smoked! Why is it so delicious?

The process of cooking food is also the process of enjoying the aroma of food. Food undergoes complex changes during the heat treatment process, which allows our olfactory organs to sense different flavors.

The factors that bring about this change, in addition to the influence of the ingredients themselves, are also closely related to the heat treatment method of the ingredients.

In this article, let’s talk about how different heating methods affect the aroma and flavor of ingredients.

01

Deep frying

Most people can't get enough of fried food, it tastes so good! Some even call it an "international food" thanks to its unique aroma, golden color and crispy texture.

Tuchong Creative

Fried chicken legs, fried fish, fried prawns... I'm drooling just thinking about it.

The oil temperature is high during frying, and the thermal degradation reaction of oil provides the flavor basis for fried food. Oil will decompose into various carbonyl compounds under high temperature, among which 2,4-deoxy-1,4-dienal contributes the most.

During the frying process, caramel color changes and Maillard reactions occur, which determine whether the fried food is red or yellow in the end. The aroma formed in this process is related to oxygen- and nitrogen-containing heterocyclic compounds such as pyrazine, pyridine, and furanone.

Tuchong Creative

In addition, different types of cooking oil will also affect the aroma of fried food. If you use peanut oil for frying, there will be a distinct peanut flavor; if you use sesame oil for frying, it will have a sesame aroma; and if you use coconut oil for frying, it will also give the food a coconut aroma.

However, even though fried foods are very tempting, it is better to eat less for health reasons. Fried foods have increased fat content, soaring calories, and may also produce trans fatty acids. Frequent consumption not only increases the risk of obesity, but is also particularly detrimental to cardiovascular health.

02

barbecue

The method of cooking food by grilling has a long history, dating back to our primate ancestors. Few people can control their desire for the aroma of grilled food. Wherever there is grilling, there is aroma. Especially in the streets and alleys in summer, the aroma of grilling is simply mouth-watering!

Modern barbecue generally uses charcoal to burn. The temperature of charcoal when it is burning and glowing is far higher than 700 ℃. It can cook food through high temperature without affecting the taste of the food.

Tuchong Creative

One of the reasons why grilled food has a special flavor is that the natural ingredients in the meat undergo the Maillard reaction during the heating process.

In addition, flavor droplets are the key to the flavor of grilled food. After the food drippings burn, they will emit many aromatic compounds that cover the food.

For example, the drippings of fruit juice contain sugars, proteins and oils, and the drippings of meat contain a lot of fat. These ingredients will be burnt under the high temperature of charcoal and stimulated into aromatic molecules that return to the smoke, giving the food an aromatic taste.

However, grilling is usually done at high temperatures, which can easily produce heterocyclic amines, which are aromatic compounds with carcinogenic and mutagenic effects, especially when foods with high protein content are exposed to high temperatures, such as livestock, poultry, and fish.

Therefore, it is recommended not to eat barbecue too often, and it is best to eat it with fresh fruits and vegetables. Because fresh fruits and vegetables contain ingredients that can inhibit the activity of carcinogens, which can reduce the harm of eating barbecue to the body.

03

Smoked

Smoking is different from barbecue. It is a cooking method that uses smoke produced by incomplete combustion of wood to smoke food. It can give food a unique smoky flavor.

The type of wood you choose when smoking is the key to affecting the flavor of food. Wood contains lignin. The higher the lignin content, the harder the structure and the higher the burning temperature. Lignin is the key substance that makes smoked food delicious. Most of the aromatic compounds in the smoked flavor come from the burning of lignin. When the temperature is higher than 300 ℃, lignin will decompose into phenolic compounds with an earthy fragrance, exuding the special aroma of vanilla and cloves, as well as spicy and sweet taro.

Tuchong Creative

In addition, the sugars in the cellulose and hemicellulose in the wood will also decompose when they are burned, giving off sweet, fruity, floral and bready aromas. Most wood also contains protein, which can produce browning reactions to color food and also produce baking aromas.

These complex flavor compounds seep into the food, giving the smoked food a unique and complex flavor.

Hickory is often chosen for its rich, sweet, aromatic, and browned flavor, while chefs in the Pacific Northwest smoke salmon with alder wood, Mexican barbecue uses mesquite, and other countries use grapevines to smoke meats.

In addition, smoking can extend the shelf life of food and prevent it from spoiling prematurely because the acidity of burning smoke is not conducive to the survival of microorganisms, and the phenolic compounds in the smoke are also effective antioxidants that can prevent food from becoming rancid.

Tuchong Creative

During the processing of smoked food, carcinogens such as polycyclic aromatic hydrocarbons and benzopyrene will be produced. Pollutants such as formaldehyde, N-nitroso compounds and β-carboline alkaloids may also be present. Eating smoked food frequently will increase the risk of gastric cancer and esophageal cancer.

04

Micro-wave oven

Microwave ovens are a widely used cooking method in modern cooking. Microwaves stimulate the vibration of water and oil molecules, which generates heat during the vibration process, thereby heating the food. Microwaves can penetrate 1 to 2 cm below the food. It is more suitable for foods with high water content. If the water content of the food is too low, it may become dry and hard after microwave cooking, making it difficult to chew, such as steamed buns.

Tuchong Creative

Microwave heating has a good effect on preserving the flavor and nutrition of food. For example, fruits and vegetables contain vitamins, carotene and flavonoids. If they are cooked using traditional methods such as boiling, frying, etc., more nutrients will be lost. Proper microwave cooking has less effect on these ingredients.

In addition, the flavor of food is produced by alcohol, aldehyde, acid, ester and other low-boiling-point aromatic compounds under high temperature conditions. Microwave processing of food is often short-term and the surface temperature of the food is low, which is not conducive to the Maillard reaction, and the water dissipates quickly, so the flavor is inferior to other cooking methods.

05

Boiled

Boiling is the simplest cooking method, and the aroma of food is relatively small. During the boiling process, the food loses some of its aroma, while some new smells are produced. Especially long-term cooking will produce a stronger aroma.

This is because non-enzymatic reactions will occur in food during the boiling process, mainly including hydroxylamine reaction, decomposition of vitamins and carotenoids, oxidation of polyphenol compounds, degradation of sulfur-containing compounds, etc.

Tuchong Creative

Compared with frying, grilling, smoking, etc., boiling is still a more recommended cooking method. It not only retains more nutrients, but also does not produce harmful substances during the cooking process, and is relatively healthier.

However, it should be noted that most fruits and vegetables cannot be boiled in water for a long time, which will not only lead to a large loss of flavor components, but also cause excessive loss of nutrients.

Summarize:

Cooking food is also a process of enjoying delicious food. Although some of it tastes delicious, you still need to be moderate for the sake of your health!

References:

[1] Harold Mackey, Food and Cooking: Vegetables, Fruits, Spices, and Grains. Translated by Cai Chengzhi. Beijing Fine Arts Photography Publishing House. August 2013.

[2] Zhang Cong, Chen Dewei. Research progress on the flavor of fried foods[J]. Journal of Food Safety and Quality, 2014, 5(10): 3085-3091. DOI: 10.19812/j.cnki.jfsq11-5956/ts.2014.10.021.

[3] Zhou Xiaoyan. Cooking Technology[M]. China Textile Press, 2008.

[4] Written by Nathan Myhrvold, Chris Young, and Maxime Billet; Photographed by Ryan Matthew Smith and Nathan Myhrvold; Translated by the Modernist Cuisine Translation Team. Modernist Cuisine: The Art and Science of Cooking, Volume 2: History and Foundations [M]. Beijing: Beijing Fine Arts Photography Publishing House, September 2016.

[5] Lü Huichao, Peng Zengqi, Liu Senxuan, Muneer Jamali, Li Junke, Wang Fulong, Hui Teng, Cui Baowei, Liu Shixin. Determination of barbecue flavor and heterocyclic amine formation in a model system under mild conditions [J]. Food Science, 2015, 36(08): 150-155.

[6] Guo Yang, Teng Anguo, Wang Wenhang. Research progress on the effects of smoking on the flavor and safety of meat products[J]. Meat Research, 2018, 32(12): 62-67.

[7] Cui Yapeng, Zhang Guozhi, Zhang Kangyi. Research progress on the effects of microwave treatment on food flavor and nutritional components[J]. Grain Processing, 2020, 45(06): 62-65.

Author | Xue Qingxin, member of Chinese Nutrition Society, registered dietitian, health manager, public nutritionist

Review | Han Hongwei, Director and Researcher of Risk Communication Department, National Food Safety Risk Assessment Center

This article is produced by the "Science Rumor Refutation Platform" (ID: Science_Facts). Please indicate the source when reprinting.

The pictures in this article are from the copyright gallery and are not authorized for reproduction.