Spray drying conditions affecting characteristics of Sericin powder derived from Thai native silk waste water

Abstract

 Sericin, a globular protein in silk cocoon, could be used in the cosmetics, phamatical, food, and textile industries. Silk waste water containing sericin has been uselessly disposed. Without a good waste management, silk waste water might cause an environmental problem. This research work aims to prepare sericin powder from silk waste water using spray drying process. Two varieties of Thai native cocoons (Nangnoi Sakonnakorn and Samrong) were soaked in 95 oC hot water for a specific time to obtain the silk waste water with a concentration of 2 obrix. The silk waste water was then spray dried to study influences of the inlet air temperatures (100-140 oC), inlet air volumetric flow rates (28 and 35 m3/h), and silk waste water feed rates (9 and 12 ml/min) on properties of the sericin powder obtained. The experimental results showed that moisture content of the sericin powder decreased with increasing air temperature, increasing air volumetric flow rate and decreasing feed rate. The feed rate was also found to affect particle size, color, and antioxidant activity of the sericin powder. Drying at higher feed rate provided powder product with larger particle size, more intense color, and higher antioxidant activity than drying at lower feed rate. However, product yields obtained from different drying conditions were not significantly different (p>0.05). Properties of the sericin powder prepared from waste water of the two varieties of silk cocoons were comparable.