Phase Separation Induced in Gelatin-Base Coacervation Systems by Addition of Water-Soluble Nonionic Polymers I: Microencapsulation

A microencapsulation procedure in which water-soluble nonionic polymers (especially, polyethylene oxide or polyethylene glycol) were added to gelatin-base coacervation systems is described. The advantages of this method are: (a) The addition of a small amount of polyethylene glycol (PEG) or polyethylene oxide (PEO) to a complex coacervation system (e.g., gelatin-acacia) allows microencapsulation to occur over an expanded pH region (pH 2–9 in gelatin-acacia), (b) These polymers induce phase separation in an aqueous solution of gelatin alone and enable the preparation of gelatin-coated microcapsules not only in the vicinity of the isoelectric point (pH 9.0), but over a wide pH range (pH 5.5–9.5). (c) Spherical single-seeded micro-capsules can be obtained.