If you spit the bite out of your mouth upon remembering or at the break of dawn, your fast is not invalidated. However, if you swallow the bite: if the swallowing occurred before the bite was removed from your mouth, you must make up the fast and pay expiation; because the soul does not reject this bite. If the swallowing occurred after removing the bite from the mouth and the bite was not hot but cold, which the soul finds repulsive, then there is no expiation required, only making up the fast, if you are someone who finds such things repulsive. If you are someone who does not find such things repulsive, then you must also pay expiation. Refer to Al-Mabsut 3: 141, Al-Durr Al-Mukhtar and Rad Al-Mukhtar 2: 99, Al-Hadiyah Al-Ala'iyah pp. 162-163, and Bada'i Al-Sana'i 2: 95, 100.