In Ketubos 10:, Rabban Gamliel seats a lady on a barrel of wine to test her virginity. If wine can be smelled on her breath she is not a virgin, and if not then she is; there is no odour from the lady's mouth, and so she is declared a virgin. A source from Judges, about Yavesh Gilad, is also brought down there.
The barrel of wine test appears anatomically problematic, very easy to repeat and verify, and not something I would expect to have only a peshat. I have searched the internet using Google, and checked obvious seforim, but all the perushim I have found have been literal- with some trying to provide medical justification for why a non-virgin woman would have breath smelling of wine if she sat on a wine barrel, e.g here.
Is there a non-literal interpretation of the barrel of wine test somewhere in Chazal? Does the lady, the barrel of wine, and her breath, symbolize something?