Answer: The Gemara in Masechet Berachot (40a) and Rashi ibid. state that one may not speak in between reciting a blessing on food and eating it because this constitutes an interruption between the blessing and the eating and there is no longer any connection between them, as we have discussed several times.
If One Spoke Between Reciting the Blessing and Eating
If one did speak, one must recite the blessing over again. Maran Ha’Shulchan Aruch rules likewise. Nevertheless, if one spoke words related to the food one is eating, for instance, if one recited a blessing on bread, realizes that there is no salt before him to dip the bread in, and then exclaims, “Bring Salt,” one would not recite another Hamotzi blessing, for speaking things related to the blessing does not constitute an interruption between reciting the blessing and eating. Needless to say, this only applies if one has already spoken; however, one should preferable not speak between reciting the blessing and eating at all.
If One Interrupted Between Reciting the Blessing Before Swallowing But After Tasting the Food
The Poskim discuss whether or not one may speak after one has tasted the food but not yet swallowed it. Similarly, if one puts a candy in one’s mouth and immediately tastes the candy’s flavor but he has not yet swallowed any part of it, may one speak at this point or must one wait until he swallows a bit of the candy?
The source of this doubt lies in the basic understanding of the enactment of blessings: Were blessings instituted for the enjoyment of the palate which one experiences while tasting any food or was the primary reason why blessings were in enacted because of the actual eating (swallowing) of the food, as the verse states, “And you shall eat and you shall be satisfied and you shall bless.” Since many Poskim write that one must wait until one swallows, one should preferably act stringently and not speak until one has swallowed a bit of the food one is eating. Nevertheless, Maran Rabbeinu Ovadia Yosef zt”l rules that if one speaks after tasting the food but before swallowing it, one does not recite the blessing again, for the primary enactment of blessings was not for swallowing the food; rather, it was for the beginning of the eating, i.e. immediately when one’s palate enjoys the taste of the food.
Summary: It is forbidden to speak about anything after one has recited a blessing until one swallows some of the food. If one mistakenly spoke between reciting the blessing and eating about something related to the eating, such as if one is eating bread and said “bring salt”, one should not recite another blessing and should rather immediately proceed to eat. Similarly, if one speaks before swallowing the food, one should not recite the blessing again.