Definition of taste
Eating is a process that uses all of our senses; our five senses allow us to see, hear, taste, touch and smell aspects of our environments. Our senses allow us to create an internal representation and interpretation of the outside world. Our eyes respond to the colors of beautifully presented food. Red tomato sauce, green peppers, and yellow corn are visually appealing. The aromas of many foods delight us. The smell of freshly baked apple pie or roasting lasagna is enough to lure us into the kitchen for a taste. We associate eating an apple with the familiar sound of the crunch that we hear as we bite. The effervescence in soda tingles our tongues. Pudding feels smooth and soft. Coffee feels hot and warms us on a cold winter morning, while ice cream feels cold and refreshes us in the summer. If you enjoyed your dinner, you likely would say that it tasted good, not that it sounded good, no matter how crunchy the carrot sticks were. Researchers are still unlocking the mysteries of how our taste receptors work. All of the examples above show us that the enjoyment of food requires all of our senses. The sense of taste intermingles with each of the other senses to provide a complete "taste" experience.
Although most of us take the sense of taste for granted, it is a sense that is crucial to our survival as a species. Our sense of taste lets us know which items are okay to eat and which are not. We don?t just rely on our sense of taste to determine if a food is appetizing. For survival purposes, we also rely on taste to determine if a food is either fresh or spoiled. The taste of good food is a sense that we all enjoy. Since foul smelling items and bitter tasting foods are often harmful, poisonous, or spoiled, people naturally choose to avoid these types of foods. For example, people are naturally repulsed by the foul odor of rotten eggs, caused by the emission of hydrogen sulfide, the foul odor of rotting fish, caused by the emission of various amines such as ammonia, or the unpleasant smell of some poisonous mushrooms. This avoidance is protective because these and other foul smelling items may in fact be spoiled or toxic.
Decreased taste perception in the elderly and chronically ill can be contributing factors toward malnutrition in these populations. The sense of taste is also involved in the regulation of one?s caloric intake and the sense of control or lack of control over one?s weight. As Registered Dietitians, a better understanding of the biochemistry of taste will allow us to better serve those clients who rely on us for guidance.
The sense of taste occurs by a multipart process that begins when food substances interact in a specific manner with our taste buds, the taste sensors on our tongue. Each taste bud-food substance interaction is a physical-chemical type of interaction that relays the sense of flavor to our brains. Our brains interpret the overall taste of a particular food transmitted by nerves. Although many aspects of the mechanism of taste have been uncovered, much remains unknown. Researchers are still in the process of unlocking the mysteries of how our taste receptors work.
The senses of taste and smell, also known as olfaction, allow us to detect chemical properties of foods and other substances in our environments. The sense of smell works in concert with our taste buds to provide us with an overall sensation of taste. The sense of touch, which includes mouth feel, texture, and tactile sense, adds further dimension to the tasting experience.
Humans can perceive five different aspects of taste: bitter, salty, sour, sweet, and umami. Sodium ions, as found in traditional table salt, elicit a salty taste. Hydrogen ions (H+), as found in vinegar and lemon juice, taste sour. Simple carbohydrates, as found in sugars, oligosaccharides, and dextrins, elicit a sweet taste. Several alkaloid compounds including caffeine and quinine elicit a bitter taste.
Umami is a lesser-known type of taste that is associated with the taste of protein containing foods such as meat, cheese, and monosodium glutamate (MSG). Umami is a word of Japanese origin that means savory or meaty; it is associated with the unique savory taste of monosodium glutamate, a mildly meaty flavor and flavor enhancer. Umami was recognized as a taste component in the year 1908. Several free amino acids, most notably, MSG, elicit the umami taste response. Monosodium glutamate exhibits its taste enhancing effects when combined with 5?-ribonucleotides which are in fermenting meats and cheeses.
Although taste is a critical factor in how we rate the savoriness of a food item, a combination of numerous factors besides taste are also involved in determining whether or not we find a certain food or drink to be appetizing. The human craving for the taste of a certain food or drink is actually a desire for a combination of factors in that dish or meal. Both conscious and subconscious recognition mechanisms are involved. Due mainly to subconscious factors, the savoriness of food items is very much dependent on cultural and societal norms and upbringing. For example, a Norwegian accustomed to a diet relatively low in vegetables and bereft of hot spices would likely be displeased with a typical East Indian or Mexican dish which contains more vegetables, legumes, whole grains, and the liberal inclusion of hot spices. Likewise, an East Indian or Mexican person would probably find a traditional Norwegian dish to be lacking flavor. Other predominantly subconscious factors in our assessments of food include the manner in which food is presented or arranged, the environment in which the food is eaten, and promotional cues, such as found in advertisements or recommendations from others. As dietitians aiming to steer people into choosing more healthy foods, it is important to be aware of these other factors that strongly affect the food choices that people make.
For at least the past 50,000 years, human civilizations have been shaped in part by the desire to acquire more delectable and non-native foods. This ongoing human quest for new food has, on one hand, inspired cooperation such as trade and commerce between different groups of people. On the other hand, the quest for savory foods, particularly by growing and expanding civilizations, was a primary impetus for invasion and war. As it is well known, in the late 1400s, Christopher Columbus and his men embarked on a dangerous sea journey in an attempt to find a shorter route to India, which was known for its thriving spice trade that included nutmeg, cinnamon, and peppercorns, when they inadvertently ran into America. In various human societies, food plays a prominent role in religion, medicine, and in class distinctions. (1)
Our perception of food is due to both genetic and cultural factors. Humans are known to be genetically inclined to favor foods higher in sugar and fat, and we can look back at our evolutionary past to better understand why we crave these food components. A possible explanation for this inclination is that long ago when food scarcity was common, higher calorie foods such as sweet fruits, fatty nuts, and bone marrow (high in monounsaturated fat) were particularly advantageous to the survival of early Homo sapiens. Neanderthals did not have much of a choice in what they ate. They hunted for meat, captured fish from rivers and seas, and ate vegetables that they found growing as wild plants. (1) In the past, our ancestors? cravings for sweets and fats motivated them to look for things to eat like sweet wild berries, which may have also been a good source of vitamin C, bone marrow which is rich in several minerals and high fat meats which provided a good source of calories as well as protein. Therefore, this craving was advantageous at the time. However, cravings for sweets and fats are not advantageous today. Our current behavior patterns are not just based on what information is in our genes as taste and smell have both genetic and cultural components. (2, p. 11-39)
The desire for salt led humans to take in sodium chloride and other needed minerals and ions. It also plays an important function in water balance and homeostasis. Our ability to detect sour taste helps us to detect unripe fruit, spoiled foods, and allows us to detect the acid-base makeup of our foods. Sweetness attracts us to fruit, which nourished our ancestors, and bitter repels us from poisons; our ancestors may have died from food poisoning if they weren?t able to detect bitter and putrid tastes. For example, humans can detect extremely low concentrations of butyl mercaptan, a bitter chemical found in rancid butter, rotting gingko fruit, and putrefying fatty substances. This ability prevented many cases of food poisoning. (2, p. 70-81)
