Effect of germination level on properties of flour paste and cooked brown rice texture of diverse varieties

Abstract Brown rice is rich in dietary fibre, minerals, and bioactive compounds but it is not widely accepted by rice consumers due to its hard and chewy texture and the length of time required to cook. Some of these aspects may be improved by germinating brown rice and choice of suitable varieties. The effects of germination levels and variety differences on pasting characteristics of flour and textural properties of cooked grain were examined using eight varieties, six non-glutinous and two glutinous, with amylose content varying between 4 and 25%, grown in aerobic conditions under two irrigation frequencies. Germinated brown rice was produced via two methods, by incubating soaked paddy for 30 h and until each variety achieved 70% germination. In each variety, increased germination percentage was linearly associated with reduced pasting characteristics (final, peak and setback viscosities), and varieties with faster germination speed tended to have lower viscosities. While stickiness and variety differences were maintained with germination, cooked whole grain had 24 N lower mean hardness than brown rice, and hardness of some non-glutinous varieties became similar to those of glutinous varieties. Cooking time of germinated brown rice required 5 min less than brown rice despite a slight increase in pasting temperature. Irrigation frequency during paddy growing had little effect on pasting characteristics and textural properties of all varieties. These results suggest that germination of certain varieties greatly reduced the final viscosity of flour and hardness of cooked brown rice, and future research could exploit the advantages of variety differences further.