Our friends - the diatoms & Merlot

I just finished filtering the 2004 Vidal at Stag's Hollow winery. The Vidal is one of the better white hybrids for cool climate wine making. In years when the vitus vinifera have a tough go of it, the Vidal comes through with flying colours. It buds late. This is handy in case there is a spring frost. Late killing frosts are notorious for knocking production back by damaging tender young buds.

The Vidal also ripens late and by the time harvest comes around it seems almost impervious to the vagaries of autumn weather. The birds seem to eat it last. It's a great aromatic varietal. It makes a great patio sipper.

The filtering of wine consists of some kind of apparatus that holds the medium in place as the wine passes through it. The purpose is to screen and retain impurities of a certain size. Often the process requires substantial pressure to force the wine throughout the system and maintain the integrity of the medium.

Today I was using diatomaceous earth (DE). This is a substance used through out the beverage industry in its quest to satisfy the consumer's demand for clarity. It's also used in the filtration of non-edibles as well.

It resembles talcum powder when dry and gooey clay when wet. It's made up of the fossilized remains of diatoms. Tiny creatures that inhabit the ocean and leave tiny skeletons that have an affinity for forming complex web like structures when compressed on a filter screen.

The beverage is forced through the screens with the diatomaceous earth already in suspension. It creates a cake that continues to build as the filtration proceeds. The wine passes through the cake but any large particles are caught. The size of the captured particles depends on the type of DE used. DE is generally used for rougher filtrations at the beginning of the filtration procedure. Other media are used to finish or "polish" the product at the end.

Why filter? Lots of wine can emerge from the cellar visually brilliant. But many substances, including wine spoilage microbes, are smaller than what most people can see. Filtration allows wine to proceed to packaging in a more stable state. The wine maker can have more confidence that it will reach the customer as he intended it to be.

Some people say that filtration diminishes the wine, that it takes something out. I say what's the point of selling wine unless you can guarantee the wines stability? I put so much into my wine that a little filtration isn't going to be noticed.

2003 Merlot - I promised this a couple of posts back. I'm in the process of doing a final blend on the Stag's Hollow Merlots for 2003. The estate is great and contains about 4% Cabernet Sauvignon. It will drink well on release but I don't think it will peak until a few more years of bottle age. Instead of a Renaissance version of Merlot this year Stag's Hollow has plans to produce a Merlot-Cabernet Sauvignon blend for the first time. About 20% of the blend will be Cabernet Sauvignon from an excellent vineyard - Heritage in Osoyoos. The cab really comes through - cocoa and cigar box, a hint of kelp and eucalyptus. Hope you have a chance to enjoy it as much as I had putting it together.