A decision is expected today on an official investigation into winemaking practices at Kingston Estate, one of Australia's largest wine companies.The winery's export licence was suspended on May 1 after allegations that it had illegally used oenocyanin (tannin) to colour red wine and silver nitrate, sulphuric acid and ethanol.UK retailer Waitrose has taken the investigation seriously and withdrawn its stocks of Kingston Estate. A Waitrose spokeswoman said: "We withdrew our stocks from the shelves last week. We only had 60 cases and at £13.99 a bottle hardly any had been sold so it has not had an adverse affect on us financially." The allegations against Kingston were by two former employees, work-experience students from the University of California at Los Angeles, USA.The students, who worked at Kingston Estate during the just-completed vintage, left the company after a now-resolved employment dispute. They made the allegations in an e-mail to fellow students. They also alleged that The Australian Wine and Brandy Corporation, which is conducting the investigation, and the Australian Winemakers' Federation have said that there has been no health risk to consumers. Under Australian regulations, the use of silver nitrate and sulphuric acid is illegal, the use of oenocyanin as a tannin is legal but not when used for colouring. Ethanol may legally be used in fortified wines.Kingston Estate's managing director, Bill Moularadellis, has said that the winery is co-operating fully with the AWBC in its investigation. The wine in question was bulk wine produced under contract for cask wine.The family-owned winery, in Australia's largest wine-producing region, the Riverland of South Australia, crushed 20,000 tonnes in 1999, making it one of the top 15 wineries.It produces a full-range of wines, from discount to super-premium products, and exports about 60% of its production, mainly to Europe and the USA.Chris Snow