Improving the malting qualities of rice grain using gibberellic acid (GA3)

Abstract

Application of exogenous gibberellic acid stimulates high production of hydrolytic enzymes in malts. To investigate this effect on rice malt, different concentrations of the GA3 hormone were applied with the aim of establishing the optimum level that significantly affects rice malting qualities. Parameters evaluated included germination energy, shoot length, and enzymatic activity (diastatic and alpha amylase) of the rice malt. Shoot length, and enzyme activity were significantly affected by the GA3 hormone at concentrations of 0.001, 0.1, 10, and 100 mg/L. 10 mg/L of GA3 solution stimulated the highest production of diastase (1305 U/g dry malt), and shoot length of 2.93 cm after 60 hours of germination. Alpha amylase activity was increased by twofold. The maximum diastatic activity of GA3 treated rice grains was found on the 8th day of germination, occurring earlier than the untreated which peaked at the 10th day. GA3 treatment at a concentration of 10mg/L is adequate to stimulate higher production of diastase in rice malt