What is one to do if he began chewing on a food, or drinking a liquid, and then remembered that he did not say a blessing?
Foods: It is forbidden to say a blessing while eating food. Accordingly, one who forgot and entered food into his mouth without saying a blessing [and remembered in the midst of chewing the food], then he must spit it out and say the blessing, if it is a type of food which will not become repulsive to the person after it is spat out [and he will thus return and eat it]. If, however, the food will become repulsive after it is spat out [and will thus no longer be eaten due to its repulsiveness], then one is not required to spit it out and is rather to place the food into one of the sides of his mouth and say the blessing. [Thus, for example, if he began eating gum or a candy without a blessing, he is to spit it out and then say the blessing. If, however he began chewing bread, or a grape and then remembered that he forgot to say a blessing, he is to move it to the side of his mouth and say the blessing. In all cases, if he did not yet begin chewing the food, then he is to remove it and then say the blessing. In the event that one entered so much food into his mouth that he cannot move it to the side and say a blessing, then its law follows the same law as liquids, as explained next.]
Liquids: Coming up soon!
 Michaber 172:2; Tur 172:2; Brachos 50b; Yerushalmi Brachos 6:1 [44b]; Ketzos Hashulchan 55:8
 Brachos 51a; Yerushalmi Brachos 6:1 [44b]; Michaber 172:2 regarding one who forgot and began eating a food without a blessing; M”A 172:4; Taz 172:2; Ketzos Hashulchan 5:10 “It is forbidden to say a blessing with food in one’s mouth”; Beir Heiytiv 173:3; M”B 173:7
The reason: As the verse states “Yimalei Pi Tihilasecha” which means that one’s entire mouth must be involved in praising Hashem. [See Brachos ibid; M”A 172:4; Taz 172:2; Beir Heiytiv ibid; M”B ibid; Ketzos Hashulchan ibid; Kaf Hachaim 172:4]
 The reason: This is due to the prohibition against destroying food.
Does this apply according to all opinions: Some Poskim rule that according to the ruling of the Raavad regarding liquid that one is to spit it out if he has more liquid available, then the same applies here as well. [Toras Chaim Sofer 172] Other Poskim, however, rule that even the Ravaad agrees in this case that one is not to spit out the food and cause it to go to waste as the concept of Yimalei Pi Tehilasecha is not as severe as eating without a blessing. [Maharam Benet on Mordechai Brachos 7:53; Magen Giborim 172; See Piskeiy Teshuvos 172:4]
 See P”M 172 M”Z 2 in name of Rambam and M”B 172:6 “Such as beans and the like which are hard.”; Ketzos Hashulchan ibid
 M”B 172:8 “strawberries or grapes”