Microencapsulation of spirulina using spray-drying technique: impact on morphological and structural characteristics

Spirulina's valuable properties are often overshadowed by its off-flavour. This study demonstrates that microencapsulation using maltodextrin as wall material effectively addresses these challenges. The encapsulated spirulina (ES₁) exhibited good encapsulation efficiency (49.70%) and yield (40.55%), with low wettability (0.08 ± 0.03gmin^-1) and hygroscopicity (6.16 ± 0.18%). Significant composition changes were observed in ES₁, including total lipids (6.22 ± 0.50g 100 g^-1), carbohydrates (51.97 ± 0.75g 100 g^-1), moisture (6.42 ± 0.24g 100 g^-1), protein (31.59 ± 0.11g 100 g^-1), ash (3.78 ± 0.85g 100 g^-1) and water activity (0.23 ± 0.01A_w). Phytopigments, such as chlorophyll a (32.02 ± 0.15 mg/g), chlorophyll b (23.12 ± 0.30 mg/g), total carotenoids (3.13 ± 0.00 mg/g), c-phycocyanin (17.78 ± 0.26 mg/g), as well as vitamin B9 (0.5937 ± 0.52 µg/g) and antioxidant activity (25.21 ± 3.29%), were well retained. The microcapsules displayed a mean particle size of 2.18 ± 2.91 µm with a PDI of 0.795 ± 0.03. Morphological and structural analyses (SEM-EDS, FTIR, XRD, UV-Vis) confirmed electrostatic interactions within the wall matrix, promoting amorphization and stability. Overall, spray-drying microencapsulation of spirulina with maltodextrin effectively improved storage stability by lowering water activity.