2. 2 taste and smell

2. 2 taste and smell 2. 2. 1 taste 2. 2. 1. 1 biological basis of taste

The food tastes like a soluble substance in a food soluble in saliva or in a food solution stimulates a sense of taste in the mouth, transmitted to the heart of the brain through a system of odour-spiriting that collects and transmits information, and finally produced a sense of taste, or a sense of taste, through the analysis of an integrated nervous central system of the brain. The taste sensor in the mouth is mainly a taste bud, followed by a free nerve ending. Taste buds are microstructures that are extremely active in the mucous membranes of the mouth. They have a tasting point, which connects with the odour nerve. The number of taste buds decreases with age, and so does the sensitivity to taste。

2. 2. 1. 2 biological basis of taste

(1) the structure of the odour-bearing substance the structure of the odour-bearing substance is the internal factor influencing the taste. Sugars, such as glucose, sugar cane, etc. Are more sweet, while acids, such as lemon acid, acetic acid, are more sour, salt, such as sodium chloride, potassium chloride, etc., are more salty and sour。

(2) temperature tastes are generally sharper at 10 to 40°c, of which 30°c is the sharpest. The degree of exposure to temperature varies from odour to taste, with the temperature having the greatest effect on sugar sweetness and the least effect on hydrochloric acidity。

(3) concentrations and solubility generally give comfort to people at any perceived concentration, and pure bitterness at any concentration is almost unpleasant, acid and salty at low concentrations, and discomfort at high concentrations; saliva is a natural solvent for food only when it dissolves, and saliva is distributed in the mouth by mumps, gills, tampons and countless small salivas. Since a odour-bearing substance can only be spread to the oscillator in a dissolved state, thereby affecting the oscillation, the oscillation is also influenced by the medium in which it is located. The adhesiveness of the medium affects the spread of the soluble odour substance to the sensor, and its properties change the solubility of the odour-based substance or the release of the active ingredient of the odour-based substance。

(4) age, sex and physiological conditions there has been no significant change in taste sensitivity for persons under 60 years of age, while those over 60 years of age are significantly less sensitive to the four original tastes of salt, acid, bitterness and sweetness. This is due, on the one hand, to an increase in age, to a decrease in the number of tasting buds on the tongue's nipples and, on the other hand, to the fact that the disease of the elderly themselves hinders the sensitivity to taste sensations; gender has little difference in the effect on tastes, which is more sensitive for women than for men, while acids are more sensitive for men than for men; certain diseases or anomalies in the body lead to loss of taste, loss of taste or deterioration; and, on the other hand, to a decrease in taste sensitivity as a result of hunger, as a result of the eating of food that meets the physiological needs, and from the fatigue of the taste sensor that is caused by the eating process。

2. 2. 2 smells

The sense of smell refers mainly to a sense of smelling neurons in the nasal cavity of volatile substances in foods and in the central nervous system. Sniffing is a more complex and sensitive sensory phenomenon than taste。

Sniffing stereochemicals: amoorre proposes that the odour of different substances is in fact a different combination of a limited number of dominant odours, each of which can be understood by a distinct dominant odour receptor within the nasal cavity。

Sniffing theory: dyson proposes that the snout receptor molecule resonates with the odor molecule。

Smell characteristics:

1 anticipatory people have a good sense of smell, and some odour compounds are known even at very low concentrations。

2 vulnerability to fatigue and adaptability when the central nerve of smell is in a state of negative feedback as a result of some long-term odour irritation, the sense is inhibited and adaptive; smell cells are susceptible to fatigue and insensitive to specific odours; when people's attention is distracted, the odour is not felt, and the odour is used to it for a long time。

Three individuals are very different, and people's sense of smell is very different, even if they're very sharp。

4 thresholds vary according to the state of a person's health, when a person's body is tired or malnourished, they cause a loss of smell function; when a person is sick, he or she feels that the food is flat; and when a woman has a menstruation, pregnancy or menopause, she or she may experience a loss of smell or allergie. This indicates that the physiological condition has a clear effect on the smell。

Sniffing classification (proposed by amoore): stench stinks, ether stinks, fragrances, musk, mint stinks, irritation stinks, corruption stinks。