Sight of Food
The eyes receive the first impression of foods, the size of the serving, the shapes, colors, consistency and the presence of any outward defects. Color can demote ripeness, the strength of dilution, and even the degree of heating. Black bananas, barely yellow lemonades and scorches macaroni send visual signals that better food can be found elsewhere. Color can be deceiving. If the colors of two identical fruit-flavored beverages are different, people often perceive them as tasting different. People may judge milk’s fat content by its color, but not the fat, is modified in reduces fat milk, it is often judges to be higher in fat content, smoother in texture, and better in flavor than the reduced fat milk with its original color. How food is combined on a plate also contributed to or detracts from its appeal. Imagine a plate containing baked flounder, mashed potatoes, boiled cabbage and vanilla ice cream compared to one on which are a nicely browned chicken breast, sweet potatoes, green peas, and blueberry cobbler. Most people would prefer the latter.
Smell of Food
Smell is almost as important as appearance when people evaluate a food item for quality and desirability. Although the sense of smell is not as acute in human beings as it is in many other mammals, most people can differentiate between 2,000 to 4,000 odors, while some highly trained individuals can distinguish as many as 10,00.
Since naming each of these odors separately would tax even the most fertile imagination, researchers have categorized them into major groups. One classification system recognized six groups of orders : spicy, flowery, fruity, resinous (eucalyptus), burnt, and foul. The other widely used grouping scheme consists of four categories: fragrant (sweet), acid (sour), burnt and caprylic (goaty). Regardless of the classifications, most odors are detected at a very low concentrations. Vanillin can be smelled at 2 x 10-10 mg. The ability to distinguish between various odors diminishes over the time of exposure to the smells, this perception of a continuously present smell gradually decreasing over time is called adaptation. People living near a noxious-smelling paint factory will, over time, come not to notice it, while visitors to the area may be taken aback by the odor.
On a more pleasant note, imagine the scent of chocolate chip cookies wafting through the house as they bake. How does the smell get carried to people, and why is the smell of something baking more intense than the smell of cold items like ice cream? As a volatile molecules travel through the air, some of them reach the yellowish-colored olfactory epithelium, an area the size of a quarter located inside the upper part of the nasal cavity. This region is supplier with olfactory cells that number form 10 to 20 million in a human and about 100 million in a rabbit, reflecting the difference in importance of the sense of smell between people and rabbits. The exact function of these specialized cells in the sense of smell is not well understood. Since only volatile molecules in the form of gas carry odor, and since heat converts many substances into their volatile form, it is easier to smell hot food than cold ones. Proteins, starches, fats, and sugar are relatively large molecules, which makes their aromas too heavy to be airborne. Lighter molecules capable of becoming volatile are detected by the olfactory epithelium by one of two pathways:
- Directly through the nose, and/or
- During eating when they enter the mouth and flow retro nasally, or toward the back of the throat and up into the nasal cavity. Who has not experienced the feeling of bubbles tingling in the nose brought on by drinking a carbonated drink while simultaneously being made to laugh unexpectedly? This illustrates the connectedness of the two areas.