Drying method
Another factor which affects the quality of the final product is the drying method applied to the extracted wet β-glucans. The drying method is affecting the particle dimensions and the structure of β-glucans as their biological activity.[34] There are three ways for β-glucan drying: air-drying, freeze-drying, and spray-drying. Spray-drying is referred as the most appropriate compared with the other two drying methods because the biological activity of spray-dried β-glucans is prolonged. Spray-dried yeast β-glucans are characterized by a neutral flavour with a creamy and smooth mouth feel. For this reason, they are most appropriate for use in food and beverage production.[15, 16] Also, the morphology of extracted β-glucans is an important quality factor. Agglomerated glucans enhancing less the macrophage phagocytosis than the micro-particle β-glucans.[34] For that reason, mechanical and sonication techniques for reducing the size of β-glucan particles, by disruption of their agglomerates and improving their biological activity have been proposed.[35] The applied drying methods for the produced soluble or insoluble glucans of each method are reviewed in Table 3.