Spray-drying microencapsulation of polyphenols by polysaccharide from yeast cell walls

This study used polysaccharide (PS) from yeast cell walls to encapsulate polyphenols (PP) extracted from green tea (a good antioxidant substance) to avoid the effects of sensitive factors such as temperature, light and oxygen, and to preserve its stability and bioactivities. The objective of this study was to investigate the effects of four types of wall material (PS-MD (maltodextrin), PS-whey, whey, and MD). After selecting the most appropriate wall material, the study continued to investigate the effects of the ratios of the core to the wall material (1:1, 1:2, 1:3 and 1:4, w/w); the inlet air temperatures of spray-drying (130, 140, 150 and 160 °C); and the feed flow rates (04, 05, 06 and 07mL/min) on the microencapsulation yield (MEY) and the microencapsulation efficiency (MEE). The results showed the best settings as follows the wall material being PS-MD, the ratio of PP to the wall material as 1:3 (w/w), the inlet air temperatures at 140 °C, and the feed flow rate at 05mL/min. Under those conditions, the MEY and the MEE were found to be highest as 31.118mg/g and 86.73%, respectively. When examined by scanning electron microscopy (SEM), they had various sizes and spherical shapes and some of them had smooth or concave surfaces. As a result, it could be concluded that polyphenols were successfully encapsulated in the PS-MD matrix by spray-drying and the application to some food products could be further studied.