The Halacha strictly prohibits making a Hefsek (interruption) between the recitation of the Beracha and the initial consumption of the food or beverage. For example, if one would speak extraneously after reciting Hagefen before he took his first sip, he would have to make another Beracha.
There are also several lesser-known applications of this Halacha in which answering Amen to an extraneous Beracha constitutes a Hefsek.
First, Hacham Ovadia, in Yabia Omer, teaches that women should not answer Amen to the Beracha "Lesheb BaSukkah," which is recited after Kiddush on Sukkot. Since women are not obligated in the Misva of Sukkah, saying Amen constitutes a Hefsek (interruption) between the Beracha of Hagefen and the drinking of the wine.
The second application, also brought by Hacham Ovadia, involves a case in which a man has already made Habdalah and then repeats it for his wife. In such a case, the Halacha states that the man should say all the Berachot, except for "Boreh Me’oreh Ha’esh" on the flame, which is recited by the woman. The reason is that it is not clear that the man may recite that Beracha twice. In such a situation, the man should not answer Amen to his wife’s Beracha on the flame. Doing so constitutes a Hefsek (interruption) between his Beracha of Hagefen on the wine and his drinking.
The third application arises during the Berachot under the Hupa. Popular custom has added a Beracha on Besamim (spices) in between the Hagefen on the wine and the Birkat HaErusin (wedding blessing). The source for this addition is not clear, but it does present several issues of Hefsek. First, the Hatan and Kallah should not answer Amen to the Beracha on the Besamim, since it interrupts between the Hagefen and their drinking the wine. Second, the rabbi should not answer Amen to the Beracha on the Besamim, and he certainly should not recite that Beracha himself, since that is a Hefsek between the Hagefen and the Birkat HaErusin. It follows that if the Hatan and Kallah do not answer Amen, then they should not smell the Besamim. It seems that this custom of Besamim under the Hupa causes more problems than it solves. While this does not mean that it should be abolished, people should be aware how to prevent this custom from violating the Halachic integrity of the wedding ceremony
SUMMARY
Interrupting between a Beracha and consumption of the food or drink is strictly prohibited. If one did talk in between the Beracha and the drinking, he must repeat the Beracha.
Answering Amen to an extraneous Beracha also constitutes an interruption. For example, a woman should not answer Amen to the Beracha of "Lesheb Basukkah," after Kiddush. In addition, a man making Habdalah for his wife should not answer Amen to his wife’s Beracha on the flame. Finally, the rabbi and the wedding couple should not answer Amen to the Beracha on the spices under the Hupa.
