Our Mishna teaches that a person who takes a vow that he will not drink wine is allowed to eat food that has wine mixed into it, even if he can taste the wine. If, however, when he took his neder he said “I vow that I will not taste this wine,” if enough fell into the food that the taste of the wine can be discerned, then he would not be allowed to eat it.
The Ran explains that in this case we follow the language of the neder as it was expressed. If his vow prohibited wine, we understand that his intention was to forbid the drinking of the wine itself and not wine in food, even if there was enough to leave a taste of wine in the food. If, however, the statement that he made prohibited tasting wine, we must interpret his intention as relating even to the taste of wine.
The Sha”kh in the Shulḥan Arukh rules that this is true in the case of an ordinary person who takes a vow to refrain from drinking wine. If, however, the person who takes the vow is someone who does not like the taste of wine and makes the neder for that reason, then even if he said that he would refrain from drinking wine – and says nothing about the taste of the wine – we will interpret his vow to apply to the taste of wine. Rav Ephraim Navon, in his book Mahane Efra’im, rejects this distinction and argues that we only seek an interpretation of his words if his statement is inherently unclear. In this case, we will simply accept the simple meaning of his neder.
Some of the commentaries have a different reading of the Gemara. According to them, the second case is different from the first not because of an emphasis on taste, but rather because the person taking the vow specified “this wine” rather than wine in general. Once the person specifically prohibited “this wine” it becomes like any other forbidden food and cannot be consumed if there is even a small taste of it.