Pasting Properties and Amylose Contents in Landraces of Myanmar Rice

Abstract

　Rice is an important staple food crop that plays an important role in meeting the energy and nutrient requirements of the world population. Myanmar has various resources of rich genetic variations of rice and is home to various ecotypes differentiated to adapt diverse growing environments. Even though people in Myanmar consume a wide variety of rice for dietary meal and snacks, the local population inhabiting the mountainous regions prefer the sticky and waxy rice that has low amylose content. The rice with low amylose content are often found as native species in mountainous regions in Myanmar, whereas in Japan, such varieties of rice are mutant varieties. The present report is aimed at characterizing the pasting properties of 24 landraces of rice collected from the mountainous regions of Myanmar. In general, the pasting property of rice is influenced by amylose content in the rice starch. Rice landraces in mountain regions in Myanmar are tentatively classified into 3 groups according to the amylose content as waxy (0～2.5%), low (3.0～6.0%), and medium (10～17%) varieties. The waxy group displayed the lowest values for all Rapid Visco Analyzer parameters and had similar values as the low group. On the other hand, the values were relatively higher in the medium group. Therefore, the pasting properties were found to be predominantly dependent on the amylose content in rice, similar to most other rice species. Of all the landraces employed in this study, 2 landraces (NGA-CHEIK and KHAO SIAM) exhibited unique pasting properties, which could be the result of the amylopectin structure in their starch granules.