If a fasting person tastes the food they are cooking, the fast is invalidated if the food is swallowed. If it is not swallowed, then doing so without any necessity is considered makrūh (disliked). Fasting is not merely abstaining from eating and drinking; it is also an act of self-discipline and training in patience. Tasting food is viewed as contrary to the spirit of fasting and is considered objectionable due to the risk of swallowing.
However, in certain situations, a valid excuse (ʿudhr) may exist. For example, a woman whose husband is irritable or fastidious may need to check the salt or taste of the food. In such cases, there is no harm in tasting the food only with the tip of the tongue, provided that it does not pass down the throat.