Compare the following biblical passages that contain eucharistic overtones and/or describe celebrations of the Eucharist:
(a) The Feeding of the Five Thousand (Luke 9:10-17)
(b) The Last Supper (Mark 14:22-25; Matthew 26:26-29; Luke 22:14-20)
(c) The Appearance on the Road to Emmaus (Luke 24:13-36)
In the Feeding of the Five Thousand, there is no real structure to the meal, which most likely indicates that it is an ordinary meal, and not a festive or ritual meal. Luke mentions five loaves of bread and two fish specifically, and states that the disciples were able to fill twelve baskets with the leftover bread.
In contrast, the Last Supper is a Passover Meal, which is an annual ritual meal. Bread and the cup are mentioned specifically. Wine is not mentioned by name in Luke’s Gospel, but the fruit of the vine is practically synonymous.
In the Appearance on the Road to Emmaus, the meal seems to be an ordinary one. The two disciples arrive in the village, they sit down for a meal, and they recognize Jesus when he breaks the bread just as he did at the Last Supper.
The bread is the only specific item that appears in all three of these events. Since the bread is understood to represent Jesus’ body, I think that it is clear that the bread is present whenever Jesus is present. The wine (Jesus’ blood) only appears in the Last Supper, right before his death.