Resistance of 17 mesophilic lacticStreptococcusbacteriophages to pasteurization and spray-drying

Abstract

SummaryFor 17 phages active againstStreptococcus cremoris, Str. lactisandStr. lactissubsp.diacetylactis, the killing efficiency of pasteurization (logNo/N) at 72°C for 15 s in skim-milk showed large variations from > 6 to 0; the efficienty of killing during spray-drying ranged from 3.7 to 0.2 and phages survived well storage of milk powder at room temperature. Destruction in a heat exchanger was found to be greater than that calculated from biphasic curves obtained by heating phages in sealed ampoules. No relationship was established between lytic classification of phages and their heat resistance.