Spray-drying microencapsulation of ascorbic acid: impact of varying loading content on physicochemical properties of microencapsulated powders.

Background: There is increased interest in the food, pharmaceutical and cosmetic industries in using ascorbic acid as an important component in the human diet for health support and disease prevention. However, its use as an ingredient is limited by its high instability and sensitivity to environmental conditions. Microencapsulation technology has been proposed to increase the stability of ascorbic acid. The aim this work was to evaluate the effect of ascorbic acid loading rate on the physicochemical properties of encapsulated ascorbic acid. Loading contents of ascorbic acid of 6%, 9%, 18%, 36%, 54% and 72% were trialled using spray drying in conjunction with starch-based encapsulating agents.

Results: The results showed that the loading content has a significant effect on ascorbic acid retention, yield, moisture content, water activity, colour change, particle size and distribution of microcapsules. Morphology of microcapsules also was assessed using environmental scanning electron microscopy, showing that the microcapsules had good structure and integrity for a loading content of 18% and even as high as 54%. At levels beyond this, capsules showed a lack of coherence and integrity of the outer shell.

Conclusions: The results indicated that ascorbic acid microparticles at various loading rates have a substantial impact on physical and chemical properties of microcapsules. Loading content can be selected to ensure colour uniformity and minimal effects on colour during food fortification processes. © 2020 Society of Chemical Industry.