Symbolism, Imagery, Allegory
Thanks, Rostand. Now We're Hungry.
Food and drink aren't just thrown into this play so the actors have something to snack on. This imagery also let the audience know how serious/not serious the onstage action is... in case we're too distracted by Cyrano's shnoz to follow the plot.
In the first two acts, food and wine play the role of comedic relief and showy wordplay in the characters of Lignière and Ragueneau (just look at the scene with the orange girl, or the hilarious poetic-puff-pastry stuff). However, it becomes much more serious in the last three acts, especially when the Cadets at Arras are starving.
Food isn’t exactly trivial anymore. Roxane risks her own life to show up with a feast for the men, although to be fair her mind was probably more on Christian than on any food she was bringing to the soldiers. Love, too, is briefly referred to in food imagery when Roxane describes her desire for cream (good love poetry), not milk and water (Christian’s lame offering of "I love you").