Swallowing remnants of food in between teeth does not invalidate the prayer
13-1-2014 | IslamWeb
Question:
If I ate and did not rinse my mouth before performing the prayer, does swallowing the remnants of food in between my teeth invalidate the prayer?
Answer:
All perfect praise be to Allaah, The Lord of the worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
Swallowing the remnants of food that remain in between one’s teeth does not invalidate the prayer. Ibn Qudaamah 
said, "If one eats or drinks deliberately during the prayer, his prayer is invalid. This is according to the scholarly consensus among the Hanbali scholars and we do not know of any difference of opinion (among them) in this regard. If one eats or drinks deliberately in the voluntary prayer, his prayer is invalid as well according to the correct opinion of this school of Fiqh (i.e. the Hanbali school of Fiqh). This is the opinion of most of the (Hanbali) jurists. If one unintentionally eats or drinks in an obligatory or voluntary prayer, his prayer is not invalidated according to the Hanbali school of Fiqh. This is the opinion of ‘Ataa' and Ash-Shaafi‘i 
. The Prophet, sallallaahu ‘alayhi wa sallam, said: "Allaah The Exalted Forgives my Ummah's mistakes, forgetfulness and actions upon which they are forced."
Al-Awzaa‘i said, "If one eats or drinks absent-mindedly in an obligatory or voluntary prayer, his prayer is invalid and this is the opinion of the Hanafi scholars since eating is a process that entails a long period of time (i.e. nibbling, chewing, swallowing, and so on) and there is no chance that one may do all of that inattentively during the prayer."
Al-Awzaa‘i also said, "In case of swallowing the remnants of food in between his teeth, if such remnants are a small and insignificant amount that flow with the saliva, then this does not invalidate the prayer."