（1）Fermentation technique of Lactobacillus hilgardii

GABA is produced from L-sodium glutamate as raw material by fermentation technique of Lactobacillus hilgardii with the following processing steps, such as pasteurization, cooling, activated carbon filtration, spray drying steps, whose content is more than 20％.

（2）Plant enrichment method

GABA can be obtained from some special plants, such as tea and rice. When tea is processed by changing some physical techniques (for example, temperature or pressure), or unpolished rice is processed by germinating, the concentrations of GABA in both increase significantly. GABAs from these edible resources are safe and reliable, definitely without toxic side effects. However, we are unable to get enough mounts and purity of GABA by these methods. GABA concentrations of these products are still on microgram level. They cannot yet meet human body's demand for GABA.