Stephan Claassen (FNB), Ryan O'Connor (MC), Juandré Bruwer, Diemersdal winemaker, Success Lekabe (MC) and RJ Botha, chairman of Sauvignon Blanc SA.
Winter Ferment revolutionised the style of South Africa’s Sauvignon Blanc offering, becoming the only local rendition of this variety to be vinified from Sauvignon Blanc juice frozen at harvest, and then vinified four months later after thawing the juice.
This process leads to a final wine expressing above-average levels of thiols, components responsible for Sauvignon Blanc’s tropical flavour profile.
Thys Louw, the sixth generation Louw to own, farm and make wine on Diemersdal Estate, says that despite winning this award for eight years on the trot, a FNB Sauvignon BlancSA Top 10 accolade remains a highlight for any South African Sauvignon Blanc producer.
“Sauvignon Blanc has shot to the fore as the country’s leading wine in terms of local sales and exports,” says Thys, “and the success of this variety is ascribed to many reasons. There is the fact that the taste profile of Sauvignon Blanc appeals to consumers, as well as that the exuberance of flavour makes the variety easily recognisable. However, the reality is that South African Sauvignon Blanc would not have achieved this amount of commercial success had it not been the exceptional quality of wines the country is making.
“Here, the FNB Sauvignon Blanc SA Top 10 has played an enormous role. The judging process is exceptionally rigorous, and with around 160 entries annually the competition analyses the complete profile of Cape Sauvignon Blanc offerings. The standards that the Top 10 have set since inception in 2007 have inspired myself and South African Sauvignon Blanc producers to ensure we make the best possible use of our vineyards growing in the various pockets of Cape terroir which have shown to be among the best in the world for cultivating this magical variety.”
In a quest for optimum tropical fruit expression in Sauvignon Blanc, Thys released the first Winter Ferment in 2017. The wine is made by freezing the grape-must to -20°C soon after the grapes were harvested in February. The frozen must is thawed in June, inoculated and allowed to ferment as per normal.
Although, according to Thys, the results of this freezing and late “winter” ferment are anything but normal.
“For reasons unknown, the wine shows flavours and chemical analyses I have never encountered in any of the Sauvignon Blancs made at Diemersdal,” says Thys. “The primary feature is the high occurrence of thiol compounds. These thiols are what gives Sauvignon Blanc the passion fruit and gooseberry flavours for which especially the wines from New Zealand have become famous.”
Louw says that while a high thiol count for a tropical style of South African Sauvignon Blanc amounts to 2 500 nanogram per litre, the Winter Ferment Sauvignon Blanc measures in the region of 5 000 nanogram per litre.
“This high thiol level is unheard of in South Africa and is more in line with what one would find in wines from Marlborough in New Zealand,” he says. “When I set out with the idea of freezing must, I wanted to see what the effect would be on the freshness and the complexity of the wine, including a possible increase in thiols. But no way did I expect the frozen juice to deliver a wine with double the thiol level we at Diemersdal had become accustomed to, and with such extraordinary tropical flavours.”
The grapes for the Winter Ferment are night-harvested at 23 degrees Balling, with crushing and destemming done reductively. Skin contact of three hours was followed by pressing and the juice is allowed to settle for 48 hours after which it is frozen solid for four months. Once the juice is thawed, alcoholic fermentation occurs at 14-16oCfor two weeks before the wine is bottled.
Thys describes the wine as the most “New World style of Sauvignon Blanc” he has made. “The wine has intense aromas of gooseberries, tropical fruit and sweet grapefruit with a core of minerality. Besides the intense fruit expression, the excellent natural acidity creates balance to the concentrated, rich mouth-filling texture.”
Besides winning various accolades since its release, Winter Ferment has been an instant hit with the consumer. “The wine began as an experiment but has, fortunately, turned into a commercial and critical success,” says Thys. “As a stalwart in the range of Diemersdal Sauvignon Blancs, Winter Ferment opens a new world of complexity and depth to the lover of this grape variety. Unlocking the potential of Sauvignon Blanc and showing what this grape can do is an integral part of Diemersdal’s ethos. We don’t know what we’ll try next, but if there is an opportunity, we’ll take it. As the Winter Ferment has shown, the possibilities in the wine world are endlessly exciting.”