Abstract: In this experiment, phage JS25 was microencapsulated with sodium alginate, and the structure of the microcapsule powder was characterized in order to determine its size distribution. In addition, the stability at different temperatures was analyzed by using planktonic phage as a control. The release characteristics of microencapsulated phage in four different food simulant systems were evaluated as well. The results showed that the phage was effectively microencapsulated with sodium alginate and CaCl2. The results of optimization by response surface methodology (RSM) indicated that the maximum microencapsulation efficiency of 88.38% was obtained when the concentrations of sodium alginate and CaCl2 were 3.72 and 2.55 g/100 mL, respectively. The size of the prepared microcapsules showed a normal distribution in the range of 20–90 μm. The microcapsules were stable for 35 d at 4 and 20 ℃, having improved stability compared with the control. The phage microcapsule powder was rapidly released in the tested food simulation systems and the release rate increased and then remained stable, reaching higher than 75% at 8 min. Therefore, this process can be used for microencapsulation of phage JS25 to improve its stability with little impact on its titer.

Key words: phage JS25, microencapsulation, structural characterization, release characteristics