Effect of soaking conditions on gamma-aminobutyric acid (GABA) and amino acids content in mung bean

Abstract

Gamma-aminobutyric acid (GABA) offers numerous beneficial effects on human health, especially as blood pressure regulator and stress control. This functional compound is usually found in grains including mung bean. Mung bean (Vigna radiate) is one of the famous grains in Southeast Asia and is usually used in cooking as porridge or dessert by local people. It is highly nutritious with protein and antioxidants. In this study, the optimum soaking conditions were determined to enhance GABA content in mung beans. An RSM with a five-level, three-factorial, Central composite Rotatable Design (CCRD) was used to determine the soaking parameters to obtain maximum GABA content, essential amino acid (EAA) and total amino acids (TAA) in mung bean. The factors that were included in the RSM analysis were temperature, time and weight of beans to water ratio. GABA and amino acids were determined by using UPLC. The optimum condition for significant GABA production (p<0.05) was determined as 40°C, 4 hrs and 1:5 of temperature, time and soaking water level, respectively with the highest GABA content quantified as 130.12 mg/100 g dry weight (DW). Model optimization and validation were done according to the optimum conditions from the RSM analysis resulting in 124.17 mg/100 g DW of GABA, closer to the predicted value (130.07 mg/100 g DW). The optimum conditions determined by RSM could be beneficial to the industry, especially functional food production to cater for the demand for health-promoting products in the market.