Bruce Jack, whose South African winery Flagstone has been sold to Constellation, has accepted a new role with the US-owned drinks giant.
He will take on overall responsibility for viticulture and winemaking of Constellation's South African portfolio.
Jack said he would work on developing a closer relationship with growers and workers, to develop a sense of pride in the brand. "My job is to impose real wine values on to a commodity," he said. "It's a big ask.
"The changes will be radical, but this is about me putting my cards on the table. I want people to take a bottle of wine off the shelf and for it to be the most sustainable wine in the world and the most complex wine at its price point."
Jack said Constellation has taken back control of sourcing the dry goods for the wine, rather than buying the finished product from brokers. He added: " Big brands have the opportunity to make a difference. It's about involving the growers and the workers, and the ethical side of things is really important."
UK off-trade sales of Kumala dropped by 34 per cent in the year to May 19 2007. The brand was owned by Western Wines before the Shropshire-based importer was swallowed up by Constellation last year.