The changes in Gamma-aminobutyric acid and polyphenols in mung beans (Vigna radiata L.) during germination

Abstract

Abstract Gamma-aminobutyric acid (GABA), an inhibitory neurotransmitter, plays a role in regulating neuronal excitability. Polyphenols naturally occur in plants and help to prevent or reverse damage in cells caused by aging, the environment, and lifestyle. Edible sprouts such as mung beans are a valuable source that presents high content of bioactive compounds. These contents in raw mung beans are very low, but they increase significantly during germination. The objectives of this study were to determine the most appropriate germination conditions, including air relative humidity (80%, 90%, and 99%), salt concentrations (0, 0.5%, 1.0%, and 1.5%), and light conditions (dark, LED, and UV-C) during the soaking and incubation processes to maximize the content of GABA and polyphenols. The results showed that all investigated treatments (air relative humidity, salt, and light) increased GABA and polyphenol levels, but LED lighting and air relative humidity of 90% were the most effective. Under those conditions, the content of GABA and polyphenols in the germinated mung beans increased about 12 and 2 times, respectively. Furthermore, the changes in GABA and polyphenol contents were different under different soaking and incubation conditions. In conclusion, the nutritional quality of mung beans, in terms of GABA and polyphenols, could be improved by controlling light and air relative humidity during germination. It is also recommended that the germination conditions, including air relative humidity, soaking in water or salt, soaking time, and incubation time should be selected depending on the desired content of GABA or polyphenols.