[Health Auditorium]

Guangming Daily reporter Cui Xingyi Guangming Daily correspondent Han Yiming

When night falls, a restaurant on the street in Wuhan is a lively scene - pots and pans are "crackling", desserts, coffee, hamburgers, lo-mei and other foods are full of aromas, filling the air and teasing the taste buds of passers-by.

Kong Jia (not her real name) has her studio on this street, and every day after work, she passes by these restaurants, surrounded by the pungent scent. But you may not know that the aroma of these "healing" foods does not necessarily come from the food itself. Not long ago, the topic of "the smell of the bakery is fake" rushed to the hot search, and the concept of "food fragrance" became popular. Many netizens were surprised: can the food fragrance still be "fake"?

In a bakery in Quannan County, Ganzhou City, Jiangxi Province, customers are buying bread. Photo by Guo Genping/Guangming Pictures

Why the enticing aroma lasts

"How is that possible? I don't believe it! ”

Kong Jia, who first heard the term "food fragrance", immediately had a strong doubt: "When I am at home on the weekend, I like to bake my own bread or biscuits, and I have never used the fragrance of food, but I will smell the same smell as the bakery." The bread itself is very fragrant, do you need the aroma of food to enhance the flavor? ”

Freshly baked bread does have a strong aroma, which is not Kong Jia's delusion. Tian Weiqun, an associate professor at the Department of Biomedical Engineering, School of Basic Medical Sciences, Wuhan University, said, "This aroma comes from the complex chemical reactions that occur during the bread baking process, mainly including the Maillard reaction and the caramelization reaction. ”

"Maillard reaction is a chemical reaction that occurs between amino acids and reducing sugars, which makes the surface of food golden yellow or dark brown, and exudes a unique fragrance, which is very sensitive to temperature, and usually increases rapidly at 160~0 °C." Tian Weiqun told reporters that due to the higher temperature and longer heating time of cooking methods such as frying, barbecue, and baking, the Maillard reaction will be more intense and produce more aroma substances. "In addition to bread, the aromas of common foods such as roasted meat, french fries, caramel, coffee, etc., are all masterpieces of the Maillard reaction."

But the fragrance is not long-lasting. "From a chemical point of view, the so-called 'aroma' is actually an aromatic organic small molecule compound with a relative molecular mass of less than 1000 dalton. Compared with macromolecular compounds such as proteins and polysaccharides, they are volatile or easily vaporized. Tian Weiqun said that within a few hours of bread being baked, these compounds will gradually dissipate, and the attractive aroma will also fade. In particular, some loose, porous breads will have a faster evaporation of their flavor.

Therefore, for some businesses that want to retain the aroma, in addition to cooking food on the spot, using food fragrance has become a new choice.

Xiaowen (not her real name), who lives in Shanghai, attended a workshop on how to run a bakery, and in one of the classes, she introduced them to several techniques to attract customers and increase sales, including using food fragrances. "One way is to drip food fragrance onto used mosquito coil sheets, which is equivalent to a homemade diffuser. You can also insert some rattan into the fragrance, but the effect is far less than the former, and the aroma will be much weaker. Xiaowen recalled, "In that class, although we didn't bake bread, I felt that I had been 'dipped in' in the aroma of bread. Even after returning home from class, the smell lingers. ”

"Food aromas can accurately reproduce the aroma of food, and the principle is mainly the clever combination of compounds with specific tastes." Tian Weiqun explained, "Food flavors are generally composed of 5 chemical elements: carbon, hydrogen, nitrogen, oxygen, and sulfur, and there must be functional groups in the molecular structure. Functional groups are atoms or clusters of atoms that determine the chemical properties of organic compounds, and their relationship with molecules is similar to that of an arm and torso. Functional groups are more active and prone to reactions, from which aromas develop. ”

The sense of smell is far more recognizant than any other sense

After being exposed to the aroma of food in the training class, Xiaowen paid more attention to the aroma in the restaurant. She found that food scents may appear in more scenes and frequencies than she thought. "It's probably not just bakeries that use it. Many restaurants either have a long kitchen and a dining area, or they don't have a back kitchen at all, use a central kitchen or pre-made dishes, but they can fill the house with fragrance, which is not unrelated to the smell of food. ”

Search for "food fragrance" on many e-commerce platforms, and a variety of categories will quickly spread across the screen - tea, milk, coffee, wine, juice, rice...... There are also merchants who directly play the banner of "hundreds of offline stores exclusively provide fragrances".

Why do people associate the smell of food with food when they smell it? This is closely related to the Proust effect.

What is the Proust effect? In the French writer Marcel Proust's novel "Reminiscences", the protagonist inadvertently smells the smell of Madeleine's small cake, and a series of past events instantly come to his mind, as if the floodgates of memory have been opened - this phenomenon triggered by smell and awakening vanished early memories is the Proust effect.

"When volatile odor molecules enter the nasal cavity, they stimulate olfactory receptor cells located in the olfactory epithelium, which in turn alters the electrical activity of neurons. Different olfactory plasma binds to different receptors and transmits information to the corresponding brain regions through different nerve conduction pathways. Yao Jing, a professor in the Department of Cell and Developmental Biology at the School of Life Sciences at Wuhan University, explained that through a series of processes such as perception, conduction, and integrated processing, our brains are able to classify and encode various odors.

That's why F&B outlets go to great lengths to create aromas – because smell has something special about it compared to other senses.

The production of sensation requires the involvement of stimuli substances, receptors, conduction pathways, and effectors. Some senses have a very limited variety of receptors, for example, people only have 3 basic tastes of sour, sweet, bitter, salty, and fresh, and there are only 0 types of cone cells in red, green, and blue on the retina. Yao Jing introduced, "In contrast, olfactory receptors have a huge gene family, with a total of about 0, accounting for about 0% of human genes. Tens of thousands of gas molecules can bind to such a large number of olfactory receptors that we can recognize smell far more than any other sense. ”

At the same time, the vast majority of sensory signals pass through the thalamus to reach the brain, and the signals from olfactory cells do not rely on the thalamus as a "relay station" and reach directly to the hippocampus between the thalamus and the temporal lobe, and the amygdala located in the temporal lobe, which respectively play important roles in cognition and memory, and in enhancing or consolidating emotional experiences. As a result, the memories evoked by the sense of smell will be clearer, more detailed, and more emotionally experienced. Yao Jing told reporters, "People can remember 1% of what they have heard, but they can only remember 0% of what they have seen, 0% of what they have heard, and 0% of what they have touched." ”

When people smell the aroma of food, the hippocampus brings back memories of past food, and the amygdala evokes corresponding emotional experiences. Yao Jing said, "From the perspective of the mechanism of feeling, there is a certain basis for merchants to hope to please customers and enhance their desire to buy through food fragrance. ”

As Bertil Hoult, an associate professor at the Institute of Retail Research at Kalmar University in Sweden, pointed out in the book "Sensory Marketing", "Smell marketing, compared with other marketing methods, has a subtle impact on consumers, and quietly influences people's consumption decisions." ”

Don't overdo it to add flavor to food

In interviews, many experts pointed out that food fragrance is not a panacea. If you want to use it to delight all your customers, it's going to be a little difficult.

After seeing the discussion about food fragrances on social media, Hong Ze (pseudonym), a sophomore at Hebei University, was also interested, and she bought 3 different flavors of food fragrances to experience.

"The price of 15ml food fragrance is not more than 0 yuan, the packaging is relatively simple, I can't see what the ingredients are, and some merchants also put out slogans such as '××× bakery exclusive'." Sniffing one by one in the dormitory, Hong Ze's feeling was, "If you smell it carefully, you can still feel that it is not the same as the original aroma of the food." After hearing this, her roommates also said that they were "tired" and "uncomfortable after smelling for a long time......

Will the smell of food permeating food in restaurants cause harm to the human body?

According to industry insiders, bread flavors are mostly blended with flavors or essential oils and volatile solvents. "If the composition of the raw materials of food fragrance is not much different from the basic chemical composition of aromatic substances in natural food, the normal concentration will not cause harm to the human body, but it should also be done in moderation and should not be overused." Tian Weiqun said.

"Some people will experience dizziness and nausea, on the one hand, it may be because the individual has a larger olfactory epithelium area and is more sensitive to odors; On the other hand, it may also be related to the excessive use of food fragrances by merchants. Tian Weiqun said that under normal circumstances, 250 olfactory cells can sense odor as long as they interact with 0 odor molecules; Once the concentration of odor molecules in the air is too high, it is likely to cause the opposite of the object and make people feel uncomfortable.

"If you have an abnormal reaction after exposure to food fragrances, you can relieve the discomfort by exposing yourself to a well-ventilated environment so that the high concentration of gas molecules can be gradually diluted." Experts remind.

Tian Weiqun also emphasized that "catering businesses should use food flavors under safe, environmentally friendly and moderate conditions to avoid adverse reactions to consumers." At the same time, food fragrance should not be used as a tool to mislead consumers. In fact, food fragrance can be regarded as a kind of food additives, and China's laws have clear regulations and standards for the use of additives, and businesses should consciously abide by them. ”

　　《光明日報》（2024年05月11日 07版）