Freshness in a wine is principally an attractive acidity and an impact the equivalent of crushing wild fennel stalks, but there's more to it, especially with red wine. The tannins have to be just ripe and along with sugar levels must keep the resulting (usually high) alcohol level in balance. What one could coin "old school" Languedoc is the opposite - baked over ripe tannins with no grip and flabby low acidity (not to mention any rustic qualities). The trick seems to require even ripening in the vineyard backed up with picking at the right time and combined with great care in the winery over things like fermentation temperature, exposure to air and the use of oak.
With white wines the equivalent holy grail is minerality, although not all wine styles strive for it. I find minerality tricky to explain and means different things to different tasters as minerals don't really have a taste plus there's no evidence that vines extract mineral tastes from the soil. For me it's a bit like the initial sensation of licking a pebble from a mountain stream but more pleasant. In wine, proper Chablis has minerality in spades. Back in the Languedoc I find it more noticeable in the less aromatic heat loving grape varieties - Terret, Grenache Blanc, Vermentino, Carignan Blanc and the like.
|Vines on Basalt terroir - said to give freshness to wines but there seems to be little real evidence|