OPTIMIZATION OF FERMENTATION PROCESS ON THE GABA CONTENT AND QUALITY OF FERMENTED RICE FLOUR AND DRY FERMENTED RICE NOODLES

This research aimed to investigate which process of fermentation can yield high levels of gamma-aminobutyric acid (GABA) in fermented rice flour. Six methods were thus selected. It was found that process number 5 (fermentation of rice in water followed by fermentation of flour in semimoist state) yielded the highest GABA content of 25.63 mg/100 g dry matter. To optimize the fermentation process of flour, the control of fermentation of rice in water at temperature of 30C for 3 days was fixed and the fermentation of flour at different temperatures and times was varied. An experimental design by response surface method to optimize the fermentation of flour at temperature range of 28-42C for 0.2-6 days to increase the GABA content was conducted. Fermentation at temperature of 35C for 3 days yielded the highest GABA content of 36.82 mg/100 g dry matter.