Impact of Freeze- and Spray-Drying Microencapsulation Techniques on beta-Glucan Powder Biological Activity: A Comparative Study

The study compares the impact of freeze- and spray-drying (FD, SD) microencapsulation methods on the content of beta-glucan, total polyphenols (TP), total flavonoids (TF), phenolic acids (PA), and antioxidant activity (AA) in commercially beta-glucan powder (Pleurotus ostreatus) using maltodextrin as a carrier. Morphology (scanning electron microscopy- SEM), yield, moisture content (MC), and water activity (a(w)) were also evaluated in the samples. Our examinations revealed significant structural differences between powders microencapsulated by the drying methods. As compared to non-encapsulated powder, the SD powder with yield of 44.38 +/- 0.55% exhibited more reduced (p < 0.05) values for a(w) (0.456 +/- 0.001) and MC (8.90 +/- 0.44%) than the FD one (yield: 27.97 +/- 0.33%; a w : 0.506 +/- 0.002; MC: 11.30 +/- 0.28%). In addition, the highest values for 13-glucan content (72.39 +/- 0.38%), TPC (3.40 +/- 0.17 mg GAE/g), and TFC (3.07 +/- 0.29 mg QE/g) have been detected in the SD powder. Our results allow for the conclusion that the SD microencapsulation method using maltodextrin seems to be more powerful in terms of the beta-glucan powder yield and its contents of beta-glucan, TP, and TF as compared to the FD technique.