Gentle wine filtration in our gravity-fed Nelson winery
Filtration is a very invasive step. But unfortunately we need to filter because we can’t bottle cloudy wine.
In the past, we contracted in a large cross-flow filter unit that pushes the wine at great speed through spaghetti-type filaments to force out unwanted particles. But it had a lot of disadvantages, starting with the chemicals needed to clean and preserve the system – phosphoric acid, caustic soda and citric acid.
We recycle all our water and therefore prefer working with steam rather than hard cleaning substances. Also it’s too big for what we require, uses lots of power and goes against our philosophy of gentle winemaking.
We decided to go back to the original principle of filtering called depth filtration using plates and frame. Traditionally, you do several passes through the plate and frame filter, going from coarse filter sheets to medium and then fine. This means three lots of pumping, three lots of dirty tanks, three lots of cleaning and you keep losing CO² on the way. What I wanted to do was to go from cloudy to sterile wine in a single pass. It’s common to have two different grades of filter sheets on the filter, but the unique concept was to add a third. Filtration experts around the world said we couldn’t do it. They wouldn’t even sell us the equipment. But I believed in the concept.
With help from a local engineer we manufactured the equipment and the new system works beautifully: it’s very quiet and energy efficient, gentle on the wine because of eliminated pumping steps and easier on the environment. I also love the fact that I now fully control filtration, rather than a contractor. Looking back, it’s been very satisfying to turn an idea into reality and take another step towards our goal of less intrusive winemaking.