The recent cold weather in large parts of our country (South Africa) made me remember a tasting I had with a winemaker. As far was icewine was concerned, he got the concept of minimum and maximum temperatures all mixed up and insisted that he harvested his frozen grapes at a minimum temperature of -7˚C. After realising that his mind was frozen from all the alcohol he had consumed during our tasting, I accepted the futility of trying to explain to him that he was actually referring to the maximum temperature requirement.
It is believed that frozen grapes were already harvested in the Roman times. Other reports indicate icewine production in Germany as far back as 1794. Another documented case stated that German vintners anticipated a very harsh fall in 1829. Grapes were left hanging on the vines for later use as animal feed. After discovery that these grapes yielded very sweet must, icewine was born! Austria, Canada and certain states in the USA also produce icewine, with China, USA, South Korea, Hong Kong and Singapore being the top markets for icewine.
In Canada, all icewine must have at least a part of it made from grapes that have been frozen naturally on the vine and then pressed whilst still frozen and without any intervention (no artificial freezing allowed after harvesting). Several challenges daunt the winemaker here. The grapes must survive animal, insect and bird activity, whilst combating mould and raisining. Only healthy, frozen grapes are thus harvested, which considerably limits the amount of grapes that can be processed. The cost of icewine it thus high, which is illustrated in an extreme case by Canadian producer, Royal DeMaria. Five cases of Chardonnay icewine was released in 2006, with a price tag of C$ 30,000 per half bottle!
On the technical side (my favourite side), I’ve just read a very interesting article about yeast adaptation concerning Riesling icewine juice fermentation. Juice with concentrations of up to 46 degrees Brix were fermented. This is quite challenging for many yeasts and it should come as no surprise that juice concentrations higher than 42 degrees Brix would not be able to be fermented to 10% v/v ethanol. Also, acetic acid produced as a function of sugar consumed was positively correlated to the glycerol produced. Glycerol and acetic acid are well-known markers for yeast stress, where acetic acid can represent up to 20% of wine TA (in icewine). Those of you familiar with icewine will know what I’m talking about when I say that it has a ‘slight’ bite to it…
A new threat to the chilly tradition that is icewine making is however gaining ground. Charles-Henri de Coussergues, Quebec icewine maker, says: “The danger now is that other wine regions start using the name ‘icewine’ for a product made the artificial way.” He is of course referring to a technique called ‘cryoextraction’. In essence, grapes are artificially frozen (-7˚C or lower) and the rest of the process is similar to traditional icewine making. The benefits here are larger production at less cost and better control over grape quality. Also, one doesn’t have to wait around for winter to do its work. But then the old-schoolers insist that traditional icewine just tastes better and more complex, possibly because of the extended hang time under harsh conditions.
The frosty debate between the ‘naturals’ and the ‘cryo-extractors’ continues. What do you think? Is there room for both these schools of thought in the already crowded wine market?
Bernard Mocke is a technical consultant for Oenobrands.