Determination of ϒ-aminobutyric acid (GABA) in jujube fruit (Ziziphus jujuba Mill.)

ϒ-aminobutyric acid (GABA) is a ubiquitous non-proteinaceous amino acid with many health-promoting benefits. GABA in some fruits has been reported previously. However, there have been no previous reports of GABA in jujube fruit. Therefore, the purpose of this study was to investigate the content of GABA in different jujube cultivars and the effect of harvest, drying and storage on GABA of jujube fruit. In six jujube cultivars studied, Z. Jujuba cv. Junzao had the highest GABA content of 333.37 µg.g⁻¹ DW, while Z. Jujuba cv. Dongzao had the lowest GABA content of 150.31 µg.g⁻¹ DW. The GABA content of jujube fruit (Z. jujuba Mill.cv.Junzao) was nearly doubled by delaying harvest time probably due to cold stress, while it was significantly decreased by the treatment of drying and storage. Interestingly, these findings suggest that normal consumption amount of jujube fruit might contain sufficient GABA to produce the effects of improving sleep and lowering blood pressure.