We will start by discussing the parallel discussion among the poskim regarding tea and coffee, and we will then see how ice cream and ices compare.
The tosefta[1] states that one fully violates the prohibition of drinking on Yom Kippur only if he drinks the relevant amount within the time it takes to drink a revi’it[2] (several seconds). This differs greatly from the corresponding time period for eating, which is k’dei achilat pras, somewhere between 4 and 9 minutes according to the mainstream opinions. The Rambam applies this distinction between eating and drinking to a broad variety of halachot where drinking is of importance.[3] In contrast, the Ra’avad[4] maintains that k’dei achilat pras is the time period for drinking, as well. His basis is a gemara[5] that says that one who drinks a revi’it of tamei[6] liquid within k’dei achilat pras becomes tamei.
Many poskim assume that one of the ramifications of this machloket is the question of how quickly one must drink a liquid in order to be obligated in a beracha acharona afterward. Since the Shulchan Aruch[7]cites both opinions but prefers that of the Rambam, he presumably requires one to drink the required revi’it without unusual pause in order to make a beracha acharona.[8] Although not all poskim accept the Rambam’s ruling even regarding Yom Kippur, because of the principle of safek berachot l’hakel (when in doubt, we refrain from possibly unnecessary berachot), one who drinks slowly should not make a beracha acharona.[9]
Some poskim say that the halachic pace of drinking should depend upon the beverage. For example, in the case of hot tea and coffee, which are difficult to drink quickly, drinking at a normal pace for those drinks warrants a beracha acharona. However, most poskim say that one should not make a beracha after drinking tea or coffee at the normally slow pace. Some recommend leaving a cooled off revi’it at the end to drink quicker and so that one can make the beracha.[10]
Normally, it takes a few minutes to consume ice cream and ices. The question, which is also the subject of considerable disagreement, is whether consuming ice cream and ices is considered like drinking or like eating. One element of the question hinges on the fact that these are foods that are liquid at room temperature but are served as a frozen solid. Some distinguish between foods and drinks depending on whether one chews it or whether it melts in his mouth and is swallowed like a liquid.[11] Others raise a possible distinction based on the food’s ingredients. In our case, ice cream, whose ingredients are more food-like, would be treated as a solid, whereas ices, which are primarily frozen, sweet, colored water, should be considered a drink.[12] Additionally, it seems logical to distinguish between ice cream and ices in another way. At room temperature, the ices mixture is similar to a drink, but it is more refreshing when frozen. In contrast, ice cream is not normally consumed in liquid form, and it functions as a cold, solid dessert.
In the final analysis, one would do better not to make a beracha acharona on ices, unless possibly if he chews them. Regarding ice cream, it makes more sense to combine the opinions that indicate that as long as one consumes a revi’it within k’dei achilat pras,[13] he should make a beracha acharona. The safest idea is to avoid the problem by eating a food (other than water)[14] that definitely requires a Borei Nefashot.