1. Material structure: sugar presents sweet taste, acid presents sour taste, salt presents salty taste, alkaloid presents bitter taste.
2. Water solubility of substances: to become a substance, it must have a certain water solubility to have a certain taste. Substances that are completely insoluble in water are tasteless, and substances whose solubility is less than the threshold value are tasteless. The higher the water solubility is, the faster the taste will produce and disappear. Generally, the substances with sour, sweet and salty taste have greater water solubility, while the substances with bitter taste have general water solubility.
3. Temperature: Generally, taste increases with the increase of temperature. The most appropriate temperature for taste is 10 to 40 degrees Celsius, especially 30 degrees Celsius, which is the most sensitive. If the temperature is higher or lower than this temperature, it will become dull. Temperature also has a significant effect on the threshold of becoming a substance.
4. Taste interaction: when two identical or different substances enter the mouth, they will change their taste in the morning, which is called taste interaction.
5. Taste sensing part: sweet taste sensing part is at the tip of the tongue, bitter taste is at the root of the tongue, salty taste is at the front of the tongue, and sour taste is at the back of the tongue.