All perfect praise be to Allah, The Lord of The Worlds, and may His peace and blessings be upon Prophet Mohammad and upon all his family and companions.
A fasting person should avoid tasting food so that nothing gets into his coelom and consequently renders his fast invalid. In addition, tasting could even drive him to eat that food because of extreme hunger and getting overcome by desire to eat.
Therefore, it is better for a Muslim not to taste food. However, if he is a chef and fears that the food might not suit the taste of the customers then he may taste it provided that nothing reaches his coelom. However, if any of that food did reach his coelom then he is obliged to remain fasting until it is called for Maghrib prayer, and he must make up for that day after Ramadan.
However, whoever has tasted food without swallowing any of it then his fast is valid and there is no sin on his part or expiation, but he has violated what is preferable from the viewpoint of Sharia. " It is recommended for the fasting person to avoid tasting food for fear that it could get into his coelom or he could eat it due to the overwhelming desire for having food." {Moghni al-Mohtajj vol.2 pp.168}. And Allah knows best.