Twenty-nine bars and restaurants, nearly half of them TGI Fridays, filled premium brand liquor bottles with lower-quality booze and sold it to patrons who thought they were buying the good stuff, authorities said Wednesday. Worse yet, investigators said at least one New Jersey bar was mixing food dye with rubbing alcohol and serving it as scotch. Officials would not say who used the rubbing alcohol. But they said no health issues were reported. A yearlong investigation by the state Division of Alcoholic Beverage Control, dubbed Operation Swill, found that the establishments had swapped out the good liquor in an effort to fool customers and increase profits. Thirteen of the restaurants cited are TGI Fridays located in central and northern New Jersey. TGI Fridays Inc. said in a statement it was working with the franchisee and owner of the TGI Fridays restaurants to investigate the allegations, which it called serious. The statement said the company had just learned of the allegations. "We have one of the most extensive bar and beverage programs in the industry, which sets a very high standard in the quality and service of our beverages," the company said. The TGI Fridays restaurants that were cited are owned by the Livingston-based Briad Group, which says on its website it has 70 TGI Fridays in seven states. The Briad Group said it opened its first TGI Fridays in New Jersey in 1993. A call to the Briad Group seeking comment was referred to TGI Fridays. The investigation, the result of citizen complaints, used confidential informants and covertly obtained samples that were tested. State officials would not say what types of premium brand liquor got swapped out with lower-quality spirits the most. They said inventory was seized and records were sought as part of the probe. State Attorney General Jeffrey Chiesa planned to hold a news conference in Trenton on Thursday to provide more details on the investigation.