Study on the effect of size reduction , heat treatment and stabilizing agent on qualities of germinated brown rice beverage with concentrated mamao (Antidesma thwaitesianum) juice found germinated brown rice were soaked in water at 40๐C for 3 hours and ground by electric blenders by using rice to water ration 1 : 28, heating condition at 85 ๐C for 15 sec and adding 0.06% carrageenan provide the product of low viscosity but high in GABA content and not separation. After that , To determine the optimal condition of germinated brown rice beverage with concentrated mamao juice production, 3 factors including concentrated mamao juice , milk powder , carrageenan found optimal production condition for germinated brown rice beverage with concentrated mamao juice were concentrated mamao juice 4% , milk powder 4.29% , carrageenan 0.08% and consumer slightly liked this product. Shelf life of germinated brown rice beverage with concentrated mamao juice kept at 4 -6 ๐C was 10 day in term of bacterial standard