Brazilian trio Douglas, Cristiano and Leonardo, Swede Rasmus Lindgren and the Uruguayan Joaquin Boghossian were told they would be training with reserve team FC Liefering, who play in the third tier, until they found new clubs.
"They won't have any more part to play for us," sporting director Ralf Rangnick told reporters. "It doesn't make any sense to have a 30-man squad."
Salzburg, taken over by the Red Bull energy drinks manufacturer in 2005, have been criticised in the past few years for the high turnover of players and coaches and for lacking a clear philosophy.
The close-season also saw Ricardo Muniz resign as coach after only two days of pre-season training and replaced by Roger Schmidt, previously with German second division side Paderborn, while Rangnick was also hired.
Thirteen players, including the five named on Thursday, have left the club or been told they have no future there, while 11 have been signed, including five on transfer deadline day.
The new players included two Norwegians, two Brazilians, one Slovakian, one Senegalese, one Ghanaian and one Nigerian.
"Without wanting to take anything away, the team only won the title last season because nobody else wanted it," said Rangnick, who also criticised the standard of the Austrian Bundesliga.
"How many players from the Austrian league took part in the World Cup qualifier between Austria and Germany (on Tuesday)? None," he said.
Red Bull's financial backing has allowed Salzburg to dominate domestic football, winning the Bundesliga four times in the past six seasons.
But the dream of qualifying for the Champions League group stage has eluded them, and this season's attempt ended with a second qualifying round defeat to Luxembourg part-timers F91 Dudelange.
Disillusioned fans have formed a breakaway club, playing in the traditional violet and under the original name of Austria Salzburg, which is now in the third tier.