Relish the Flavour – How the Brain Perceives Flavour

A
The terms “taste” and “flavour” are often used interchangeably. Strictly speaking, however, taste refers to five basic qualities: salty, sour, sweet, bitter, and umami (a characteristic of protein-rich foods such as meat and cheese). Smell plays an equally prominent role in flavour but is often underappreciated. Try holding your nose and popping a strawberry-flavoured sweet in your mouth. You will taste the sweetness but not the strawberry until you let go of your nose and the volatile chemicals from the confectionery enter your nostrils. To add to the complexity, irritants—such as carbonation or the coolness of mint—are detected not by taste or smell but by the trigeminal sense, part of the touch system adapted for the mouth.

The brain receives information about what is in the mouth from receptors—proteins specialised in picking up specific molecules—located throughout the oral and nasal cavities. Receptors for smell were identified in the early 1990s, and those for sweet, bitter, and umami only in the past two years (sour and salty tastes were somewhat better understood). Gary Beauchamp, director of the Monell Chemical Senses Institute in Philadelphia, whose group contributed to some of the findings, notes that this is more progress than has been made about taste in the past 2,000 years. A receptor for capsaicin, the molecule that gives chilli peppers their bite, was identified only in 1997.

B
The discovery of taste receptors has opened the door to mimicking, enhancing, or blocking them for desired effects—such as increasing the salty taste of low-sodium foods, reducing the bitterness of medicinal drugs, or enhancing the flavours in diets for the elderly to ensure proper nutrition. However, receptors are only part of the story. Scientists still do not fully understand how the brain distinguishes between a mouthful of milk and a bite of bread, or between chicken tikka masala from an Indian restaurant and one bought at a supermarket.

Some researchers believe the brain’s response to stimuli is a simple map of the receptors in the tongue and nose. However, a more compelling theory suggests that the overall pattern of signals creates a sense of specific flavours, which are judged based on past experiences. There are currently no useful algorithms to measure brain inputs and outputs against subjective reports of flavour sensations. This lack of measurement tools is an opportunity for neurophysiologists but a challenge for flavour and fragrance companies, whose ambition is to predict consumer preferences accurately.

C
Throughout history, flavours have been prized for their ability to make food more enjoyable and to enliven cuisine. For example, in 408, Alaric the Visigoth demanded more than 1,000 kilograms of pepper as part of his price for lifting the siege of Rome. The industrial production of perfumes began in France in the 18th century to remove odours from leather gloves, leading to the logical development of the flavour industry. By the late 1700s, extracts and essential oils such as citrus were being produced in America. In 1874, Haarmann and Reimer in Germany became the first company to manufacture synthetic vanillin on an industrial scale.

Initially, isolating and identifying gustatory ingredients was extremely challenging due to rudimentary analytical methods. The substances responsible for taste are present in trace amounts even in concentrated foods such as crushed raspberries. After 1950, improved analytical techniques allowed the detection of these trace ingredients, enabling companies to create chemical libraries with thousands of compounds.

D
Flavours can be used off the shelf, modified, or created anew, depending on a customer's needs, following the GRAS principle (Generally Recognised As Safe). It is a constant challenge to be unique, says Bob Eilerman, leader of flavour research at Givaudan, a Swiss company. Givaudan scientists explore tropical rainforests in hot-air balloons to discover new tastes and ingredients, capturing their aromas on-site for analysis and recreation in the lab.

The most potent flavoured chemicals are created through cooking, explains Anthony Blake, vice-president of food science at Firmenich in Geneva. Firmenich, Givaudan, and International Flavours and Fragrances, the industry leader in America, are the world’s leading flavour and fragrance companies. For these companies, developing unique flavours often involves deploying techno-chefs and analysts who study ethnic cuisines to inspire new creations.

E
Like artists blending pigments, professional flavourists combine 50–100 components to create a final flavour product. Acceptability is measured through sensory analysis, where panels of expert and consumer testers evaluate the product. Expert testers assess it against established standards (e.g., sweetness or vanilla intensity in ice cream), while consumer testers provide general feedback on whether they like it. This process involves multiple iterations of refinement between testers and flavourists until an acceptable taste is achieved.

However, as Alex Häusler, director of flavour excellence at Givaudan, notes, humans are not the most reliable testing instruments. People have different taste receptors and subjective interpretations, leading to inconsistencies. Texture, too, plays a significant role in eating pleasure but remains poorly understood. Why is rubbery squid enjoyable, but rubbery toast is not? While the food industry has developed methods to measure texture, such as poking peas with pins, these tests often fail to capture what happens during eating.

F
The dynamics of flavour release—how flavours appear and disappear—also resist precise measurement. Researchers at the University of Nottingham have developed an instrument called MS-Nose, which analyses the aroma molecules in a person's breath while chewing. This technology, adopted by Firmenich, has sparked interest, although results are often unique to each individual.

Physiological studies of flavour typically involve animals such as rats or bacteria with robust taste receptors. In humans, techniques like functional magnetic resonance imaging (fMRI) and positron emission tomography (PET) can track patterns of electrical activity in the brain in real time. However, these technologies are not yet sensitive or meaningful enough for flavour studies. An alternative approach might involve modifying genes in animals to trace how the brain integrates sensory signals.>> Form đăng kí giải đề thi thật IELTS 4 kĩ năng kèm bài giải bộ đề 100 đề PART 2 IELTS SPEAKING quý đang thi (update hàng tuần) từ IELTS TUTOR

G
Finding the right enhancer or blocker for a receptor often involves testing thousands of compounds—a task well-suited to automated systems. Companies like Senomyx in California use high-throughput screening to test compounds against taste receptors. Another biotech firm, Linguagen in New Jersey, focuses on developing flavour modifiers, particularly bitterness blockers.

H

The mouth is the portal of entry to the gut, and taste is the final arbiter. Innate aversions to sour and bitter substances—caffeine, nicotine, strychnine, for example—and a liking for sweet and salty ones reflect the wise choices that humanity’s ancestors made in a hostile environment. Beyond these protective and nutritional reflexes, however, taste preferences are largely a matter of culture and learning. The taste system is reasonably compliant, says Tom Scott, a neurophysiologist and dean of sciences at San Diego State University in California. Cultures are kept distinct by cuisines, and cuisines are distinguished by taste. But cuisines, like continents, have a habit of colliding. Ten years ago, few Americans cared for raw fish. Now they eat sushi almost as avidly as the Japanese. Moreover, “acquired tastes” often involve complex contradictions that play tricks within the brain. How else do you explain the liking for strong-smelling cheese or the East Asian fruit called durian that is so redolent of vomit that it is banned on public transport in some countries? Other effects resist reconciliation, like the unbearable sweetness that artichokes lend to wine. Flavour appears to belong to a family of subtle perceptions—such as recognising a voice or telling faces apart. But how does the central nervous system process all the information needed to make these fine-grained distinctions? The answer should help to develop cheaper and safer flavour compounds, as well as to perform tricks of alchemy such as turning tofu into steak. More fundamentally, identifying algorithms in the brain that transform taste into flavour, and comparing them with how people process complex sounds or tactile sensations, might reveal something about how perception really works.

Questions 1-5

The reading passage has six paragraphs (A-H).

Which paragraph contains the following information?
Write the correct letter (A-H) in boxes 1-5 on your answer sheet.

NB: You may use the letter more than once.

1. The process of the new food flavor is agreed on.
2. The reason for some natural preferences.
3. The reason why flavor has not been researched in depth in the past.
4. The explanation of lack of consistency in sensory analyzing data.
5. The wider benefits to the knowledge of researching flavors.

Questions 6-10

Do the following statements agree with the information given in the reading passage?

In boxes 6-10 on your answer sheet, write:

• TRUE if the statement agrees with the information
• FALSE if the statement contradicts the information
• NOT GIVEN if there is no information on this

1. Both taste and flavor can be experienced only in the mouth.
2. Some elements in flavor involve neither taste nor smell.
3. Ice-cream manufacturers are at the forefront of the research on flavor.
4. It is possible to accurately match the brain activity to the experience of flavor.
5. Research is being done to control the experience of taste.

Questions 11-14

Look at the following statements and the list of researchers below.

Match the person with their opinions.

NB: You may use any letter more than once.

A. Givaudan
B. University of Bath
C. University of Nottingham
D. Firmenich
E. Chemical Senses Institute
F. Linguagen

1. Matching brain activity and food input
2. Use genetic modification to track flavor signals
3. Matching textural qualities of food and sensation
4. Identify elements in certain smells

1. Interchangeably
   • Vietnamese: Thay thế lẫn nhau
   • IELTS TUTOR xét ví dụ từ bài đọc: "The terms 'taste' and 'flavour' are often used interchangeably."
   • Explanation: The words "taste" and "flavour" are sometimes used as if they mean the same thing.

1. Prominent
   • Vietnamese: Nổi bật, quan trọng
   • IELTS TUTOR xét ví dụ từ bài đọc: "Smell plays an equally prominent role in flavour but is often underappreciated."
   • Explanation: The sense of smell is just as important as taste in creating flavour.

1. Irritants
   • Vietnamese: Chất kích thích
   • IELTS TUTOR xét ví dụ từ bài đọc: "Irritants—such as carbonation or the coolness of mint—are detected not by taste or smell but by the trigeminal sense."
   • Explanation: Substances that cause a mild physical reaction, like tingling or cooling, are irritants.

1. Receptors
   • Vietnamese: Thụ thể
   • IELTS TUTOR xét ví dụ từ bài đọc: "The brain receives information about what is in the mouth from receptors."
   • Explanation: Receptors are proteins in the body that detect specific molecules.

1. Mimicking
   • Vietnamese: Bắt chước, giả lập
   • IELTS TUTOR xét ví dụ từ bài đọc: "The discovery of taste receptors has opened the door to mimicking, enhancing, or blocking them for desired effects."
   • Explanation: Scientists can copy or simulate taste receptors to modify flavours.

1. Algorithms
   • Vietnamese: Thuật toán
   • IELTS TUTOR xét ví dụ từ bài đọc: "There are currently no useful algorithms to measure brain inputs and outputs against subjective reports of flavour sensations."
   • Explanation: Algorithms are step-by-step procedures or calculations used to solve problems.

1. Synthetic
   • Vietnamese: Tổng hợp (nhân tạo)
   • IELTS TUTOR xét ví dụ từ bài đọc: "In 1874, Haarmann and Reimer in Germany became the first company to manufacture synthetic vanillin."
   • Explanation: Synthetic refers to something made artificially rather than naturally.

1. Trace amounts
   • Vietnamese: Lượng nhỏ, vết lượng
   • IELTS TUTOR xét ví dụ từ bài đọc: "The substances responsible for taste are present in trace amounts even in concentrated foods."
   • Explanation: "Trace amounts" means very small quantities of something.>> IELTS TUTOR có hướng dẫn kĩ SỬA BÀI IELTS WRITING TASK 2 ĐỀ THI THẬT NGÀY 22/8/2020 của HS IELTS TUTOR đạt 6.5 Writing

1. Sensory analysis
   • Vietnamese: Phân tích cảm giác
   • IELTS TUTOR xét ví dụ từ bài đọc: "Acceptability is measured through sensory analysis, where panels of expert and consumer testers evaluate the product."
   • Explanation: This refers to a scientific method of evaluating how food tastes, smells, or feels.

1. Dynamics
   • Vietnamese: Động lực, sự chuyển động
   • IELTS TUTOR xét ví dụ từ bài đọc: "The dynamics of flavour release—how flavours appear and disappear—also resist precise measurement."
   • Explanation: "Dynamics" refers to the changing and active nature of something.

1. High-throughput screening
   • Vietnamese: Phương pháp sàng lọc tốc độ cao
   • IELTS TUTOR xét ví dụ từ bài đọc: "Companies like Senomyx in California use high-throughput screening to test compounds against taste receptors."
   • Explanation: A method used to quickly test many substances to find useful ones.

1. Innate
   • Vietnamese: Bẩm sinh
   • IELTS TUTOR xét ví dụ từ bài đọc: "Innate aversions to sour and bitter substances... reflect the wise choices that humanity’s ancestors made."
   • Explanation: "Innate" means something that is natural or inborn, not learned.

1. Cuisines
   • Vietnamese: Ẩm thực
   • IELTS TUTOR xét ví dụ từ bài đọc: "Cultures are kept distinct by cuisines, and cuisines are distinguished by taste."
   • Explanation: Cuisines are styles of cooking associated with specific cultures.

1. Acquired tastes
   • Vietnamese: Khẩu vị tập làm quen
   • IELTS TUTOR xét ví dụ từ bài đọc: "Acquired tastes often involve complex contradictions that play tricks within the brain."
   • Explanation: These are tastes people learn to enjoy over time, despite initially disliking them.

1. Perception
   • Vietnamese: Nhận thức, cảm nhận
   • IELTS TUTOR xét ví dụ từ bài đọc: "Flavour appears to belong to a family of subtle perceptions."
   • Explanation: "Perception" refers to how the brain interprets sensory information.

1. E
2. H
3. C
4. B>> IELTS TUTOR hướng dẫn PHÂN TÍCH ĐỀ THI 30/5/2020 IELTS WRITING TASK 2 (kèm bài sửa HS đạt 6.5)
5. B
6. False
7. True
8. Not given
9. False
10. True
11. D
12. E
13. B
14. C