Wine vinegar comes from oxidised wine. The alcohol is oxidised to the aldehyde and then to the acid (which we know as vinegar).  So wine vinegar is ‘off’ wine which has some wine taste but is much more acidic. It will also have a little of the fruity taste of the aldehyde.

C2H5OH (alcohol) goes to C2H4O (acetaldehyde) which goes to CH3COOH (acetic acid). In those days, it was a cheap soldier’s drink that they used to quench thirst, so it made sense for them to offer it when Jesus said he was thirsty.