Starch Spherulite Production via High Temperature Spray Drying

Open Access
- Author:
- Tirio, Beth Ann
- Graduate Program:
- Chemical Engineering
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- April 23, 2009
- Committee Members:
- Dr Greg Ziegler And Dr Wayne Curtis, Thesis Advisor/Co-Advisor
Dr Greg Ziegler And Dr Wayne Curtis, Thesis Advisor/Co-Advisor - Keywords:
- spherulite
high temperature spray drying
starch - Abstract:
- This project was undertaken to investigate the production of starch spherulites via high temperature spray drying. High temperature spray drying is a variation of spray drying in which the operating feed temperature is above the normal boiling point of the solution. High temperature spray drying is necessary for starch spherulite production because a starch dispersion must be heated to at least 160°C, but preferably 180°C, and then cooled at a moderate rate, 10°C/min to 500°C/min. This allows the starch dispersion to gelatinize on heating and experience a phase separation into a polymer-rich phase and a solvent-rich phase on cooling. The polymer-rich phase can then crystallize into a spherulitic morphology. The elevated maximum temperature requires an operating line pressure of approximately 10 bar prior to atomization to maintain the liquid state of the feed. An Armfield Tall Form Spray Dryer/Chiller FT 80/81 was modified to be a high temperature spray drying system which could withstand an operating temperature of 180°C and an operating pressure of 10 bar. An experiment was designed to determine the effect of the feed concentration, feed flow rate, operating temperature, and drying temperature on the total percent recovery, spherulite number density, and spherulite size. In addition, the percent crystallinity of the spherulites was investigated. The system was able to successfully produce starch spherulites from 10% w/w, 20% w/w, and 30% w/w dispersions of high-amylose maize starch in deionized water. There was extreme variation in the data, however, so no statistically significant relationships between the design variables and the final product properties could be established. Post hoc analysis was done to determine the cause of the variation, however, no observable variable yielded a relationship to the final product properties. Although no statistically significant relationship could be determined between the operating conditions and the final product properties, the ability of the high temperature spray system to produce starch spherulites provides the foundation for future research.