Abstract: ObjectiveTo explore the methods of low temperature preservation for alginate-polylysine-alginate (APA) microcapsules.MethodsAPA microcapsules were prepared with static electricity, and underwent hypothermal treatment respectively through methods of program control, gradient by icebox and put in liquid nitrogen directly, finally preserved in liquid nitrogen. The form and permeability of APA microcapsules were checked after rewarming.ResultsThe rates of integrity, crenation and damage were (91.2±1.57)%, (3.1±0.81)% and (5.7± 2.62 )% in the program control group; (85.3±1.42)%, (5.2±0.74)% and (9.5± 3.81 )% in the gradient by icebox group; (14.5±1.57)%, (84.1±3.47)% and (1.4±2.62)% in the directly put in liquid nitrogen group. The membrane permeability of full APA microcapsules after frozen and reworming was not changed obviously.ConclusionThe program control method can preferably preserve APA microcapsules at low temperature and keep them having normal form and permeability.

Key words: alginate-polylysine-alginate (APA) microcapsule, low temperature preservation, membrane permeability