Skim milk powder was reconstituted in distilled water (reconstituted skim
milk, RSM). The RSM (12%,w/w) was then heated to 95 °C for 90 min using a GFL1002 water bath.After being cooled to 37 °C, the prepared RSM was inoculated with L. casei LC2W
(5 × 106 CFU/g) andS. thermophilusST1 (5 × 106CFU/g).Cultures without phage were designated LC-ST, while those supplemented with S. thermophilus phageφ101 were designated LC-ST-P. RSM wasinoculated with singleL. caseiLC2W (5 × 106 CFU/g or 1 × 107
CFU/g)or S. thermophilusST1 (5 × 106CFU/g or 1 × 107CFU/g) as a control
(designated LC and ST). The samples of RSM fermented byL. caseiLC2W
(designated LC-P) or S. thermophilus ST1 (designated ST-P) in the presence of S. thermophilus phage were also cultured and analyzed. All of the fermented milk cultures were incubated at 37 °C and were monitored automatically (recorded every 5 min) for pH using a Cinac system during milk acidification. The number of viable L. casei and S. thermophilus cells were selectively counted during fermentation using MRS (fermented milk sampled every 12 h for 72 h) and LM17 (fermented milk sampled every
2 h for 24 h)agarrespectively.