sparkling Gamay, Gamay isn't exactly a universally beloved grape itself so to see it held in such high esteem over the lowly Grolleau is cause for concern indeed.
The thing about Grolleau is that you have probably had the grape at some point but were unaware of it. It is the main grape in the fairly common Rosé d'Anjou, which at one point in time accounted for over half of all production in the Anjou region of the Loire Valley. It is permitted in a few other AOC rosé wines in the Loire Valley, but is not allowed in anything other than rosé wines. The grape is thought so little of that the AOC does not allow red wine production from it at all, so Grolleau has ended up as one of the workhorse grapes for rosé wines, especially Rosé d'Anjou. The popularity of Rosé d'Anjou has fallen off over the past few decades, though, and as a result of the lack of demand (and possibly of the pressure from high-powered wine critics), plantings of Grolleau have fallen substantially as well.
If nobody likes poor old Grolleau, then why grow it in the first place? For starters, it's a reliably high-yielding vine, producing a large, steady crop which is a sure sign that growers are going to love it. The name "Grolleau" comes from the French word grolle, which means crow, and when the berries are ripe, they can take on a very dark, almost black appearance which is thought to be reason for the name. Though the skins can get very dark, they also tend to be fairly thin which means that it has problems in the vineyard and in the winery as it is susceptible to a large number of diseases and is unable to contribute a great deal of flavors since the thin skins lack the phenolic punch of thicker-skinned grapes. It is thought to be related to Gouais Blanc, a seldom grown grape that is one of the parents of Chardonnay, Auxerrois, Gamay and a host of other grapes.
I was excited to come across a bottle of the 2010 Olivier Cousin "Le Cousin Rouge" at City Feed and Supply in Jamaica Plain for about $24. The winemaker, Olivier Cousin, is a biodynamic farmer who has about 12 hectares of land under vine and who only uses indigenous yeasts for his wines. He also submits many of them to extended skin contact to extract more color and flavor. The grapes for this wine come from 30 year old vines that yield a paltry 30 hl/ha. His total production for this particular wine is around 3,500 bottles.
Dornfelder or Beaujolais," and I stand by that assessment. Your enjoyment of this wine will line up almost exactly with your tolerance for and enjoyment of funky secondary flavor and aroma characteristics. If you like your wine squeaky clean, steer clear of this as it has nothing that you're looking for. If you love the smell of a horse barn on a screaming hot day, then you may have just discovered your vinous Nirvana.