The bread in this context refers to the body of Christ Jesus, the Messenger of Truth. And the one who dipped the bread into the bowl is One who is under the teachings of the Truth, yet goes against it. There are many such people in this world today, even some Christians themselves, may it be that they do it consciously or unconsciously, because they do not recognize the Truth when they see it.
MT 26:20 When evening came, Jesus was reclining at the table with the Twelve. 21 And while they were eating, he said, "I tell you the truth, one of you will betray me."
MT 26:22 They were very sad and began to say to him one after the other, "Surely not I, Lord?"
MT 26:23 Jesus replied, "The one who has dipped his hand into the bowl with me will betray me. 24 The Son of Man will go just as it is written about him. But woe to that man who betrays the Son of Man! It would be better for him if he had not been born."
MT 26:25 Then Judas, the one who would betray him, said, "Surely not I, Rabbi?"
Jesus answered, "Yes, it is you."
MT 26:26 While they were eating, Jesus took bread, gave thanks and broke it, and gave it to his disciples, saying, "Take and eat; this is my body."