Trade officials from the European Union and the United States made little progress after a week of negotiations in Brussels.
They have been trying to hammer out an agreement to open up Trans-Atlantic commerce.
The project, known as TTIP was launched a year ago.
The deadline for finalizing the agreement by 2015 could "definitely not be met", Rupprechter said on Thursday, on national broadcaster ORF.
He said he believed that there would be no more negotiations before the US presidential elections took place in 2016.
Rupprechter emphasised that Europe's higher standards in food manufacturing would have to be accepted - otherwise the agreement was to fail.
Furthermore he urged for more transparent negotiations by the EU commission and a "clear role" for the European parliament.
Proponents say the free trade agreement would result in multilateral economic growth while critics say it would increase corporate power and make it more difficult for governments to regulate markets for public benefit.
After a proposed draft was leaked, in March 2014 the European Commission launched a public consultation on a limited set of clauses.
A free trade area between the EU and the USA would represent potentially the largest regional free-trade agreement in history, covering 46 percent of world gross domestic product (GDP).