Besides the Domaine de la Renne, last week we also spent an hour or so taking the tour and tasting a wine at the big Monmousseau winery complex in Montrichard. It has been in business since the 1880s, the guide told me. Here's a link to the company's web site.
Monmousseau itself doesn't own any vineyards. It contracts with four or five growers to buy grapes or juice. Then it ferments the wines at its Montrichard facility, which includes 15 km (9 miles) of tunnels dug into the limestone cliffs along the Cher river. We walked through part of them.
Fines bulles de Touraine sparkling wines
To make bubbly wines, which is Monmousseau's specialty, the company uses the Champagne method, which can't be called that because wineries outside the Champagne region aren't legally allowed to use that term. Around here, it's called the méthode traditionnelle, which is the same process. The wines are called fines bulles de Touraine — tiny bubbles of Touraine.
Sediment in a bottle undergoing fermentation, and a view of the ceiling inside the caves
Part of the fermentation of sparkling wines takes place after the wine has been put into bottles and capped. The minimum time the in-bottle fermentation takes is nine months, but Monmousseau lets the wines ferment in the bottle for two to four years. They have literally millions of bottles undergoing fermentation in their caves in Montrichard.
Bottles in racks, bottles in crates... bottles everywhere
When the fermentation is complete, there's a considerable amount of sediment in each bottle. The bottles are put on racks (nowadays its all done by machine) and gradually turned from the horizontal to a vertical position over a period of days. The sediment slides down into the neck of the bottles.
Also, bottling equipment
It's removed by freezing the neck of the bottle and popping off the metal cap so that the sediment pops out. Then the bottles of bubbly wine are topped off with wine or sugar syrup to give them the desired level of sweetness. They're finally corked with the familiar wire "cage" over the top to hold the cork in. I blogged about a previous visit to the Monmousseau caves nearly three years ago.