Avodah Zarah, Chapter Five, Mishnah Two
Mishnah two discusses yen nesekh that falls on other food items. The question is whether or not this causes the food to become prohibited.
1) If yen nesekh fell upon grapes, one may rinse them and they are permitted, but if they were split they are prohibited.
a) If it fell upon figs or upon dates, should there be in them [sufficient wine] to impart a flavor, they are prohibited.
2) It happened with Boethus ben Zpnin that he carried dried figs in a ship and a cask of yen nesekh was broken and it fell upon them; and he consulted the Sages who declared them permitted.
a) This is the general rule: whatever derives advantage [from yen nesekh by its] imparting a flavor is prohibited, but whatever does not derive advantage [from yen nesekh by its] imparting a flavor is permitted, as, for example vinegar which fell upon split beans.
Section one: If yen nesekh falls upon grapes, the grapes may be washed and then they are permitted. Since the yen nesekh does not have any effect on the taste of the grapes, they are permitted. If, however, the grapes were split open, then the wine could seep into them and effect their taste. In this case it is not possible to wash away the potential taste of the wine and therefore the grapes are forbidden.
Section two: If yen nesekh falls on other types of foods, such as dates or figs, the food becomes prohibited only if the wine improves the flavor of the food. The mishnah mentions a story of a person who carried figs and yen nesekh on a ship. When one of the casks of wine broke on the figs he asked the Sages if the figs were still permissible, and they permitted them. Since the wine does not improve the flavor of the figs, the person has not derived benefit from the wine and therefore the figs are permitted. This general rule, that the wine causes the food to be forbidden only if it imparts a good flavor is stated specifically in the next lines of the mishnah. The mishnah concludes with an example of another situation in which the taste is not improved, when vinegar (which comes from wine) falls on split beans.