Rice seeds contain abundant starch and high quality protein and are commonly used in food and beverage industries. Generally, rice seeds contain 6-10% (w/w) protein and 70-80% (w/w) starch. Separation of protein and starch allows for the processing of high-protein rice flour and starch hydrolysates into different products.
To simplify the production process and improve the cost effectiveness and efficiency of starch bioprocessing, scientists Su-May Yu, Chih-Ming Chiang, and Jei-Fu Shaw, all of Academia Sinica, Taipei, Taiwan, highly expressed a thermotolerant and bi-functional starch hydrolase, amylopullulanase (APU), in transgenic rice seeds.
Transgenic rice seeds were heated at high temperatures. Starch in transgenic seeds was hydrolyzed rapidly at these temperatures, and the concentration of soluble sugars increased significantly with incubation time. There is a correlation between APU activities and the starch-to-sugars conversion rates. The more APU present in seeds, the faster the rate of starch hydrolysis to sugars.
Yu and colleagues generated novel APU-transgenic rice seeds. The unique feature of heat-activated rapid autodrolysis of starch in these seeds could not only eliminate the need for the addition of commercial enzymes, but also improves the efficiency of starch bioprocessing. These seeds can be processed to simultaneously produce high-protein rice flour and sugar syrups for human consumption and broad industrial uses. A similar approach could also be applied to other cereals, e.g., maize, which might offer even less production cost than rice.
Results of this research will be presented in a minisymposium 10:10 a.m. to 11:50 a.m. Hawaii Time Wednesday, July 30, 2003 at the American Society of Plant Biologists (ASPB) annual meeting in the Hawaii Convention Center, Honolulu, Hawaii. Presenter Su-May Yu and fellow author Chih-Ming Chang are members of ASPB. Founded in 1924, ASPB represents nearly 6,000 plant scientists. ASPB publishes two of the most widely cited plant science journals: Plant Physiology and The Plant Cell.
Presenter: Su-May Yu, sumay@ccvax.sinica.edu.tw
Authors: Su-May Yu and Chih-Ming Chiang, both of the Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan; and Jei-Fu Shaw, Institute of Botany, Academia Sinica, Taipei, Taiwan.