1. Food Engineering and Bioprocess Technology, School of Environment, Resources and Development, Asian Institute of Technology, P.O. Box 4, Klong Luang, Pathumthani 12120, Thailand.
2. Kasetsart Agricultural and Agro-Industrial Product Improvement Institutes, Kasetsart University, 50, Bangkok 10900, Thailand.
3. Corresponding author. Phone: +66 25245476. Fax: +66 25246200. E-mail: athapol@ait.ac.th