S. thermophilus ST1 was grown in 12% RSM at 37 °C for 24 h. The fermented milk was centrifuged at 8000 ×g for 10 min at 5 °C. The supernatant was adjusted to a pH of 6.5 using 1 M NaOH and thenfiltered through a 0.22-μm pore-size filter (Millipore, Billerica, MA, USA) for
sterilization. The cell free supernatant was lyophilized and kept frozen (−80 °C) until use.