1. Volatility determines “smellability”
The flavor substances in flavors need to be transmitted to the nasal cavity through the air to be perceived (i.e. “smell”).

Highly volatile substances (such as limonene, ethyl acetate): They evaporate quickly at room temperature and easily release aroma, but may be lost in large quantities during processing (such as baking) or storage.

Low-volatile substances (such as vanillin, certain esters): They are not easy to evaporate and can be retained in food for a longer time, but may “not smell strong”.

Example: Citrus flavor (containing highly volatile limonene) smells fresh, but after being added to cakes and baked at high temperatures, the aroma is easy to evaporate, resulting in a weaker flavor.

2. Sensory threshold determines “tasteability”
The sensory threshold is the lowest concentration that a person can perceive for a certain flavor component.

Low-threshold substances: They can be perceived with very small amounts (such as thiol compounds, with a threshold as low as ppb level).

High-threshold substances: They require higher concentrations to be tasted (such as sucrose).

Examples:

Vanillin in vanilla flavor (high threshold), needs to be added in large amounts to taste;

While ester substances in some fruity aromas (such as ethyl hexanoate, which has a very low threshold), can produce rich flavors with a trace amount.

3. How to solve the difference between “smell” and “taste”?

Food scientists balance the two through the following methods:

Complex formula: Mix high-volatility and low-volatility ingredients to take into account both olfactory and taste experience.

For example: Add a small amount of highly volatile terpenes to mango flavor (to enhance the aroma) and match it with low-volatility lactones (to maintain the flavor in the mouth).

Microencapsulation technology: Wrap the flavor in a protective layer to delay volatilization and release it in the mouth.

Flavor enhancers: Use ingredients such as salt and sodium glutamate to lower the threshold of flavor substances and increase the perceived intensity.

Examples in life
Instant noodle seasoning packets: The strong “beef aroma” mainly relies on highly volatile compounds, but after entering the mouth, the Maillard reaction products (such as pyrazines) need to maintain a lasting flavor.

Sugar-free beverages: Due to the lack of sugar support, more low-threshold flavors (such as citrus) need to be added to make up for the blandness caused by the lack of sweetness.