High protein flour from transgenic rice seeds

Scientists in Taiwan find a new path to high-protein rice flour following studies on starch bioprocessing methods. They predict that other cereals could benefit from the process.

Rice seeds contain abundant starch and high quality protein and are commonly used in food and beverage industries. Generally, rice seeds contain 6-10 per cent (w/w) protein and 70-80 per cent (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, at the Academia Sinica in 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 hydrolysed rapidly at these temperatures, and the concentration of soluble sugars increased significantly with incubation time. The researchers found 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.

Leading scientists Yu​ and colleagues generated novel APU-transgenic rice seeds. They report that 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 improve the efficiency of starch bioprocessing.

According to the researchers, these seeds can be processed to simultaneously produce high-protein rice flour and sugar syrups for human consumption. In addition, they claim that a similar approach could be applied to other cereals, such as maize, which might offer even less production cost than rice.