Jesus was troubled in spirit, and declared, "Very truly, I tell you, one of you will betray me." The disciples looked at one another, uncertain of whom he was speaking. One of his disciples […] asked him, "Lord, who is it?" Jesus answered, "It is the one to whom I give this piece of bread when I have dipped it in the dish." So when he had dipped the piece of bread, he gave it to Judas son of Simon Iscariot. After he received the piece of bread, Satan entered into him. Jesus said to him, "Do quickly what you are going to do" […] So, after receiving the piece of bread, he immediately went out. And it was night. (NRSV 13:21-23, 25-28, 30)
He was troubled in spirit, and testified, and said, Verily, verily, I say unto you, that one of you shall betray me. Then the disciples looked one on another, doubting of whom he spake […] One of his disciples […] saith unto him, Lord, who is it? Jesus answered, He it is, to whom I shall give a sop, when I have dipped it. And when he had dipped the sop, he gave it to Judas Iscariot, the son of Simon. And after the sop Satan entered into him. Then said Jesus unto him, That thou doest, do quickly… He then having received the sop went immediately out: and it was night. (KJV 13:21-23, 25-28, 30)
The bread isn't just a tasty treat; it represents Jesus's body, which will soon be broken thanks to Judas. After he gets the bread, Judas runs out into the night, because—no surprise—he's lacking the light of the world. Check out our "Symbols" section for more juice... er, bread.