Cryo-SEM of microcapsules
Omega-3 polyunsaturated fatty acids (ω-3 PUFAs) are extremely important in human physiology. The primary source is typically obtained from fish oils. Whilst there is scientific evidence linking the consumption of ω-3 PUFAs to reduced risk of breast and prostate cancer, high blood pressure and blood circulation – the daily intake in many Western societies falls below the recommended minimum levels. Taking supplements and enrichment of foods is an ideal way to increase the ω-3 PUFAs levels in the diet.
Microencapsulation with modified cellulose by spray-drying provides an alternative way of supplementing where the final product is a fish oil powder additive. The cellulose coating surrounding the oil also improved the stability against oxidative rancidity for up to 12 – 24 months.
The microstructure and encapsulation efficiency can be determined by various methods including cryo-electron microscopy. The cryo-SEM micrograph below shows a variety of spray-dried microcapsules ranging from 1.5 to 17 μm, prepared for imaging using the Quorum PP3010. Preparation includes applying a thin layer on mounting media, vitrification in slushed N2 (-210 °C) and sputtering with Pt (1 – 2 nm). Inset image shows the cellulose coating of a fractured capsule of diameter ≈ 25 μm with wall coating thickness ≈ 571 nm.
Dr M. S. Taylor