Microencapsulation of ascorbic acid: effect of process variables on product characteristics

Area of Science:

• Materials Science
• Pharmaceutical Technology
• Food Science

Background:

• Ascorbic acid (vitamin C) is prone to degradation, affecting its efficacy and sensory properties.
• Microencapsulation offers a promising strategy to protect ascorbic acid from environmental factors and control its release.

Purpose of the Study:

• To comparatively investigate ascorbic acid microcapsules prepared by thermal phase separation, melt dispersion, solvent evaporation, and spray drying.
• To evaluate the impact of different preparation methods and materials on microcapsule characteristics and ascorbic acid stability.

Main Methods:

• Microencapsulation techniques: thermal phase separation, melt dispersion, solvent evaporation, spray drying.
• Characterization methods: Scanning Electron Microscopy (SEM), release tests, size distribution analysis.
• Stability testing under accelerated storage conditions (38°C, 84% RH).

Main Results:

• Microencapsulation prevented color change, retarded release, and masked the taste of ascorbic acid.
• Ethyl cellulose (EC) properties and additives influenced aggregation and release in thermal phase separation.
• Carnauba-based microcapsules exhibited slower release rates compared to EC-based ones.
• Higher molecular weight EC and plasticizers improved encapsulation efficiency in solvent evaporation.
• Spray drying minimized ascorbic acid loss during microencapsulation.
• Starch and beta-cyclodextrin enhanced ascorbic acid stability during storage.

Conclusions:

• The choice of microencapsulation method and excipients significantly impacts ascorbic acid microcapsule properties and performance.
• Melt dispersion with carnauba and spray drying with starch/beta-cyclodextrin show particular promise for ascorbic acid stabilization and controlled release.
• Microencapsulation is an effective strategy to improve the stability and delivery of ascorbic acid for various applications.