A person who eats a Kezayit (approx. 30 grams) of food or drinks a Rebi’it (approx. 3 oz.) of a beverage must recite a Beracha Aharona. This obligation, however, applies only if a person ate or drank this quantity within a certain time-frame. When it comes to eating, the time-frame is the duration referred to in the Gemara as "Kedeh Achilat Peras." The Halachic authorities disagree in determining this duration of time, with views ranging from two minutes to ten minutes. Hacham Ovadia Yosef rules that the period of "Kedeh Achilat Peras" extends for seven minutes. Therefore, a person who eats 30 grams of food within a period of seven minutes must recite a Beracha Aharona. If, however, a person eats slowly, and he does not eat 30 grams in a seven-minute period, then he does not recite a Beracha Aharona.
With regard to drinking, Halacha establishes a different standard. Namely, a person does not recite a Beracha Aharona unless he drinks three ounces of a beverage all at once, as a person normally drinks a glass of water. If a person sips a drink, such that he completes three ounces only over an extended period, then he does not recite a Beracha Aharona.
For this reason, one does not recite a Beracha Aharona after drinking scotch or similar hard liquors. It is nearly impossible (for most people) to drink three ounces of scotch in a single shot; people generally sip it or drink small amounts in separate installments. Therefore, no Beracha Aharona is recited. And even if a person can somehow manage to drink three ounces of scotch all at once, this is considered an unusual form of drinking, which does not require a Beracha Aharona. The Hid"a (Rav Haim Yosef David Azulai, 1724-1806) writes about such a person, "Batela Da’ato Esel Kol Adam" (loosely translated, he is the exception to the general rule), and this kind of abnormal drinking does not warrant the recitation of a Beracha Aharona.
This rule applies as well to hot drinks, such as coffee. Hot coffee can be drunk only by sipping, and therefore one who drinks hot coffee does not recite a Beracha Aharona, even if he drinks more than three ounces. And, as mentioned above, this applies even to somebody who manages to drink hot coffee all at once, like one drinks a glass of cold water. Since this is an unusual manner of drinking, it does not require a Beracha Aharona.
The Halachic authorities debate the question as to the status of ice cream and ices with regard to this Halacha. Hacham Ben Sion Abba Shaul (Israel, 1923-1998) held that ice cream is considered a solid food, and therefore one who eats 30 grams of ice cream within a period of seven minutes must recite "Boreh Nefashot." Hacham Ovadia Yosef, however, disagrees, and rules that ice cream has the status of a liquid. As such, a Beracha Aharona is warranted only if one ingests three ounces of ice cream all at once. Clearly, it is impossible to eat this quantity of ice cream or ices in this fashion, and therefore one does not recite a Beracha Aharona after eating ice cream.
Summary: One recites a Beracha Aharona after eating food only if he eats 30 grams within a period of seven minutes. One recites a Beracha Aharona after drinking a beverage only if he drinks three ounces all at once, like one drinks an ordinary drink of water or juice, but not if he drinks slowly, by sipping. Therefore, one does not recite a Beracha Aharona after drinking scotch, whisky and the like, or after drinking a hot drink, regardless of the quantity. Ice cream and ices have the status of a liquid in this regard, and therefore one does not recite a Beracha Aharona after eating ice cream or ices, regardless of the quantity.
